文章目录

  • 运算符
    • 算术运算符
    • 比较运算符
    • 逻辑运算符
    • MySQL运算符
    • 数字函数
    • 字符串函数
    • 日期时间函数
    • 条件函数
    • 系统信息函数
    • 加密函数
    • 其他常用函数
  • MySQL索引
    • 索引的概念
  • 索引的分类
  • 创建索引
    • 创建表时创建索引
    • 在已经存在的表上创建索引
    • 删除索引
  • MySQL图形化管理工具
    • PHPMyAdmin
    • SQLyog

运算符

算术运算符


（1）加、减、乘、除

mysql> SELECT 1+1,1-1,2*4,3/8;
+-----+-----+-----+--------+
| 1+1 | 1-1 | 2*4 | 3/8    |
+-----+-----+-----+--------+
|   2 |   0 |   8 | 0.3750 |
+-----+-----+-----+--------+
1 row in set (0.09 sec)

2）被除数是0时返回NULL

mysql> SELECT 3/0;
+------+
| 3/0  |
+------+
| NULL |
+------+
1 row in set (0.00 sec)mysql> SELECT 4 DIV 2;
+---------+
| 4 DIV 2 |
+---------+
|       2 |
+---------+
1 row in set (0.00 sec)

（3）取余数

mysql> SELECT 3%8;
+------+
| 3%8  |
+------+
|    3 |
+------+
1 row in set (0.00 sec)mysql> SELECT 3 MOD 8;
+---------+
| 3 MOD 8 |
+---------+
|       3 |
+---------+
1 row in set (0.00 sec)

（4） SQL的字符串转换功能

mysql> SELECT 1+'3MAIZI';
+------------+
| 1+'3MAIZI' |
+------------+
|          4 |
+------------+
1 row in set, 1 warning (0.03 sec)

（5）和NULL进行算数运算结果仍未NULL

mysql> SELECT 1+NULL;
+--------+
| 1+NULL |
+--------+
|   NULL |
+--------+
1 row in set (0.00 sec)mysql> SELECT NULL+NULL;
+-----------+
| NULL+NULL |
+-----------+
|      NULL |
+-----------+
1 row in set (0.00 sec)

比较运算符


（1）=, 比较字符串或数值是否相等，数值可直接和等值的字符串进行比较

mysql> SELECT 1=1;
+-----+
| 1=1 |
+-----+
|   1 |
+-----+
1 row in set (0.00 sec)mysql> SELECT 1=1,1='1';
+-----+-------+
| 1=1 | 1='1' |
+-----+-------+
|   1 |     1 |
+-----+-------+
1 row in set (0.00 sec)mysql> SELECT 1=1,1='1',1=2;
+-----+-------+-----+
| 1=1 | 1='1' | 1=2 |
+-----+-------+-----+
|   1 |     1 |   0 |
+-----+-------+-----+
1 row in set (0.00 sec)mysql> SELECT username,username='king' FROM student;
+----------+-----------------+
| username | username='king' |
+----------+-----------------+
| king     |               1 |
| king1    |               0 |
| king2    |               0 |
| king3    |               0 |
| king4    |               0 |
| king5    |               0 |
| king6    |               0 |
| king7    |               0 |
| king8    |               0 |
+----------+-----------------+
9 rows in set (0.00 sec)mysql> SELECT username,username!='king' FROM student;
+----------+------------------+
| username | username!='king' |
+----------+------------------+
| king     |                0 |
| king1    |                1 |
| king2    |                1 |
| king3    |                1 |
| king4    |                1 |
| king5    |                1 |
| king6    |                1 |
| king7    |                1 |
| king8    |                1 |
+----------+------------------+
9 rows in set (0.00 sec)

（2）和NULL比较是否相等时要用<=>而不是=

mysql> SELECT id,username,age,sex,sex<=>NULL FROM cms_user;
+----+-----------+------+--------+------------+
| id | username  | age  | sex    | sex<=>NULL |
+----+-----------+------+--------+------------+
|  1 | 张三      |   21 | 男     |          0 |
|  2 | 张三丰    |   31 | 女     |          0 |
|  3 | 章子怡    |   43 | 男     |          0 |
|  4 | long      |   41 | 女     |          0 |
|  5 | ring      |    9 | 男     |          0 |
|  6 | queen     |   77 | 女     |          0 |
|  8 | blek      |   85 | 女     |          0 |
|  9 | rose      |    9 | 男     |          0 |
| 10 | lily      |   39 | 女     |          0 |
| 11 | john      |   72 | 保密   |          0 |
| 12 | test1     | NULL | 保密   |          0 |
| 13 | TEST2     |   18 | NULL   |          1 |
| 14 | lll       |   18 | NULL   |          1 |
| 15 | ttt       |   18 | NULL   |          1 |
| 16 | ooo       |   18 | NULL   |          1 |
+----+-----------+------+--------+------------+
15 rows in set (0.00 sec)

（3）>, <, >=, <=

mysql> SELECT id,username,score,score>=70 FROM student;
+----+----------+-------+-----------+
| id | username | score | score>=70 |
+----+----------+-------+-----------+
|  1 | king     |    95 |         1 |
|  2 | king1    |    35 |         0 |
|  3 | king2    |    45 |         0 |
|  4 | king3    |    55 |         0 |
|  5 | king4    |    65 |         0 |
|  6 | king5    |    75 |         1 |
|  7 | king6    |    80 |         1 |
|  8 | king7    |    90 |         1 |
|  9 | king8    |    25 |         0 |
+----+----------+-------+-----------+
9 rows in set (0.00 sec)

（4）IS NULL, IS NOT NULL

mysql> SELECT id,username,age,age IS NULL FROM cms_user;
+----+-----------+------+-------------+
| id | username  | age  | age IS NULL |
+----+-----------+------+-------------+
|  1 | 张三      |   21 |           0 |
|  2 | 张三丰    |   31 |           0 |
|  3 | 章子怡    |   43 |           0 |
|  4 | long      |   41 |           0 |
|  5 | ring      |    9 |           0 |
|  6 | queen     |   77 |           0 |
|  8 | blek      |   85 |           0 |
|  9 | rose      |    9 |           0 |
| 10 | lily      |   39 |           0 |
| 11 | john      |   72 |           0 |
| 12 | test1     | NULL |           1 |
| 13 | TEST2     |   18 |           0 |
| 14 | lll       |   18 |           0 |
| 15 | ttt       |   18 |           0 |
| 16 | ooo       |   18 |           0 |
+----+-----------+------+-------------+
15 rows in set (0.00 sec)mysql> SELECT id,username,age,age IS NOT NULL FROM cms_user;
+----+-----------+------+-----------------+
| id | username  | age  | age IS NOT NULL |
+----+-----------+------+-----------------+
|  1 | 张三      |   21 |               1 |
|  2 | 张三丰    |   31 |               1 |
|  3 | 章子怡    |   43 |               1 |
|  4 | long      |   41 |               1 |
|  5 | ring      |    9 |               1 |
|  6 | queen     |   77 |               1 |
|  8 | blek      |   85 |               1 |
|  9 | rose      |    9 |               1 |
| 10 | lily      |   39 |               1 |
| 11 | john      |   72 |               1 |
| 12 | test1     | NULL |               0 |
| 13 | TEST2     |   18 |               1 |
| 14 | lll       |   18 |               1 |
| 15 | ttt       |   18 |               1 |
| 16 | ooo       |   18 |               1 |
+----+-----------+------+-----------------+
15 rows in set (0.00 sec)

（5）BETWEEN…AND…

mysql> SELECT id,username,age,age BETWEEN 10 AND 30 FROM cms_user;
+----+-----------+------+-----------------------+
| id | username  | age  | age BETWEEN 10 AND 30 |
+----+-----------+------+-----------------------+
|  1 | 张三      |   21 |                     1 |
|  2 | 张三丰    |   31 |                     0 |
|  3 | 章子怡    |   43 |                     0 |
|  4 | long      |   41 |                     0 |
|  5 | ring      |    9 |                     0 |
|  6 | queen     |   77 |                     0 |
|  8 | blek      |   85 |                     0 |
|  9 | rose      |    9 |                     0 |
| 10 | lily      |   39 |                     0 |
| 11 | john      |   72 |                     0 |
| 12 | test1     | NULL |                  NULL |
| 13 | TEST2     |   18 |                     1 |
| 14 | lll       |   18 |                     1 |
| 15 | ttt       |   18 |                     1 |
| 16 | ooo       |   18 |                     1 |
+----+-----------+------+-----------------------+
15 rows in set (0.02 sec)

（6）IN

mysql> SELECT id,username,age,age IN(21,31,41,51) FROM cms_user;
+----+-----------+------+---------------------+
| id | username  | age  | age IN(21,31,41,51) |
+----+-----------+------+---------------------+
|  1 | 张三      |   21 |                   1 |
|  2 | 张三丰    |   31 |                   1 |
|  3 | 章子怡    |   43 |                   0 |
|  4 | long      |   41 |                   1 |
|  5 | ring      |    9 |                   0 |
|  6 | queen     |   77 |                   0 |
|  8 | blek      |   85 |                   0 |
|  9 | rose      |    9 |                   0 |
| 10 | lily      |   39 |                   0 |
| 11 | john      |   72 |                   0 |
| 12 | test1     | NULL |                NULL |
| 13 | TEST2     |   18 |                   0 |
| 14 | lll       |   18 |                   0 |
| 15 | ttt       |   18 |                   0 |
| 16 | ooo       |   18 |                   0 |
+----+-----------+------+---------------------+
15 rows in set (0.00 sec)mysql> SELECT 1 IN (1,2,3);
+--------------+
| 1 IN (1,2,3) |
+--------------+
|            1 |
+--------------+
1 row in set (0.00 sec)mysql> SELECT 11 IN (1,2,3);
+---------------+
| 11 IN (1,2,3) |
+---------------+
|             0 |
+---------------+
1 row in set (0.00 sec)

（7）LIKE

mysql> SELECT 's' LIKE '_';
+--------------+
| 's' LIKE '_' |
+--------------+
|            1 |
+--------------+
1 row in set (0.00 sec)mysql> SELECT 'sD' LIKE '_';
+---------------+
| 'sD' LIKE '_' |
+---------------+
|             0 |
+---------------+
1 row in set (0.00 sec)mysql> SELECT id,username,username LIKE '____' FROM cms_user;
+----+-----------+----------------------+
| id | username  | username LIKE '____' |
+----+-----------+----------------------+
|  8 | blek      |                    1 |
| 11 | john      |                    1 |
| 10 | lily      |                    1 |
| 14 | lll       |                    0 |
|  4 | long      |                    1 |
| 16 | ooo       |                    0 |
|  6 | queen     |                    0 |
|  5 | ring      |                    1 |
|  9 | rose      |                    1 |
| 12 | test1     |                    0 |
| 13 | TEST2     |                    0 |
| 15 | ttt       |                    0 |
|  1 | 张三      |                    0 |
|  2 | 张三丰    |                    0 |
|  3 | 章子怡    |                    0 |
+----+-----------+----------------------+
15 rows in set (0.00 sec)

8）REGEXP

mysql> SELECT id,username,username REGEXP '^t' FROM cms_user;
+----+-----------+----------------------+
| id | username  | username REGEXP '^t' |
+----+-----------+----------------------+
|  8 | blek      |                    0 |
| 11 | john      |                    0 |
| 10 | lily      |                    0 |
| 14 | lll       |                    0 |
|  4 | long      |                    0 |
| 16 | ooo       |                    0 |
|  6 | queen     |                    0 |
|  5 | ring      |                    0 |
|  9 | rose      |                    0 |
| 12 | test1     |                    1 |
| 13 | TEST2     |                    1 |
| 15 | ttt       |                    1 |
|  1 | 张三      |                    0 |
|  2 | 张三丰    |                    0 |
|  3 | 章子怡    |                    0 |
+----+-----------+----------------------+
15 rows in set (0.00 sec)

逻辑运算符

1）&&，AND，||，OR（和NULL运算时结果为NULL，但真值和NULL取或时结果为真）

mysql> SELECT 2&&2;
+------+
| 2&&2 |
+------+
|    1 |
+------+
1 row in set (0.00 sec)mysql> SELECT 2&&2,2&&0;
+------+------+
| 2&&2 | 2&&0 |
+------+------+
|    1 |    0 |
+------+------+
1 row in set (0.00 sec)mysql> SELECT 2&&2,2&&0,2&&NULL,1||1,1||0,1||NULL,0||NULL;
+------+------+---------+------+------+---------+---------+
| 2&&2 | 2&&0 | 2&&NULL | 1||1 | 1||0 | 1||NULL | 0||NULL |
+------+------+---------+------+------+---------+---------+
|    1 |    0 |    NULL |    1 |    1 |       1 |    NULL |
+------+------+---------+------+------+---------+---------+
1 row in set (0.00 sec)

（2）！，NOT

mysql> SELECT NULL&&1;
+---------+
| NULL&&1 |
+---------+
|    NULL |
+---------+
1 row in set (0.00 sec)mysql> SELECT !1,!0,!NULL;
+----+----+-------+
| !1 | !0 | !NULL |
+----+----+-------+
|  0 |  1 |  NULL |
+----+----+-------+
1 row in set (0.00 sec)

3）XOR

mysql> SELECT 1XOR0,0XOR1,1XOR1,0XOR0;
ERROR 1054 (42S22): Unknown column '1XOR0' in 'field list'
mysql> SELECT 1 XOR 0,0 XOR 1 ,1 XOR 1,0 XOR 0;
+---------+---------+---------+---------+
| 1 XOR 0 | 0 XOR 1 | 1 XOR 1 | 0 XOR 0 |
+---------+---------+---------+---------+
|       1 |       1 |       0 |       0 |
+---------+---------+---------+---------+
1 row in set (0.00 sec)

MySQL运算符

数字函数


（1）CEIL()：进一取整

mysql> SELECT CEIL(1.2),CEILING(1.2);
+-----------+--------------+
| CEIL(1.2) | CEILING(1.2) |
+-----------+--------------+
|         2 |            2 |
+-----------+--------------+
1 row in set (0.00 sec)mysql> SELECT *FROM test4;
+------+------+------+
| num1 | num2 | num3 |
+------+------+------+
| 3.14 | 3.14 | 3.14 |
| 3.25 | 3.25 | 3.25 |
+------+------+------+
2 rows in set (0.07 sec)mysql> SELECT num1,CEIL(num2),CEILING(num3) FROM test4;
+------+------------+---------------+
| num1 | CEIL(num2) | CEILING(num3) |
+------+------------+---------------+
| 3.14 |          4 |             4 |
| 3.25 |          4 |             4 |
+------+------------+---------------+
2 rows in set (0.00 sec)

（2）FLOOR()：舍一取整

mysql> SELECT FLOOR(3.14);
+-------------+
| FLOOR(3.14) |
+-------------+
|           3 |
+-------------+
1 row in set (0.00 sec)

3）MOD：取余数（去模）

mysql> SELECT MOD(3,8);
+----------+
| MOD(3,8) |
+----------+
|        3 |
+----------+
1 row in set (0.00 sec)

（4）POWER()：幂运算

mysql> SELECT POW(2,3),POWER(3,3);
+----------+------------+
| POW(2,3) | POWER(3,3) |
+----------+------------+
|        8 |         27 |
+----------+------------+
1 row in set (0.06 sec)

5）ROUND()：四舍五入

mysql> SELECT ROUND(3.14567,2);
+------------------+
| ROUND(3.14567,2) |
+------------------+
|             3.15 |
+------------------+
1 row in set (0.02 sec)

（6）TRUNCATE()：数字截取

mysql> SELECT TRUNCATE(3.14567,2);
+---------------------+
| TRUNCATE(3.14567,2) |
+---------------------+
|                3.14 |
+---------------------+
1 row in set (0.00 sec)

（7）ABS()：取绝对值

mysql> SELECT ABS(-12);
+----------+
| ABS(-12) |
+----------+
|       12 |
+----------+
1 row in set (0.00 sec)

（8）PI()：圆周率

mysql> SELECT PI();
+----------+
| PI()     |
+----------+
| 3.141593 |
+----------+
1 row in set (0.01 sec)

（9）RAND()和RAND(x)：返回0~1之间的随机数，RAND(x)x相同时返回的随机数相同

mysql> SELECT RAND();
+--------------------+
| RAND()             |
+--------------------+
| 0.6808652986594153 |
+--------------------+
1 row in set (0.00 sec)mysql> SELECT RAND();
+--------------------+
| RAND()             |
+--------------------+
| 0.7984468916416605 |
+--------------------+
1 row in set (0.00 sec)mysql> SELECT RAND(1);
+---------------------+
| RAND(1)             |
+---------------------+
| 0.40540353712197724 |
+---------------------+
1 row in set (0.00 sec)mysql> SELECT RAND(1);
+---------------------+
| RAND(1)             |
+---------------------+
| 0.40540353712197724 |
+---------------------+
1 row in set (0.00 sec)

（10）SIGN(x)：返回x的符号，x为负数、0、正数分别返回-1、0、1

mysql> SELECT SIGN(12),SIGN(0),SIGN(-12);
+----------+---------+-----------+
| SIGN(12) | SIGN(0) | SIGN(-12) |
+----------+---------+-----------+
|        1 |       0 |        -1 |
+----------+---------+-----------+
1 row in set (0.00 sec)

（11）EXP(x)：计算e的几次方

mysql> SELECT EXP(3);
+--------------------+
| EXP(3)             |
+--------------------+
| 20.085536923187668 |
+--------------------+
1 row in set (0.03 sec)

字符串函数



（1）CHAR_LENGTH(S)：返回字符串的字符数；LENGTH：返回字符串长度

mysql> SELECT CHAR_LENGTH('maizi'),LENGTH('maizi');
+----------------------+-----------------+
| CHAR_LENGTH('maizi') | LENGTH('maizi') |
+----------------------+-----------------+
|                    5 |               5 |
+----------------------+-----------------+
1 row in set (0.00 sec)mysql> SELECT CHAR_LENGTH('啊'),LENGTH('啊');
+--------------------+---------------+
| CHAR_LENGTH('啊')  | LENGTH('啊')  |
+--------------------+---------------+
|                  1 |             3 |
+--------------------+---------------+
1 row in set (0.00 sec)

2）CONTACT(S1, S2…)：将字符串合并为一个字符串，和NULL连接时结果为NULL

mysql> SELECT CONCAT('HELLO','WORLD');
+-------------------------+
| CONCAT('HELLO','WORLD') |
+-------------------------+
| HELLOWORLD              |
+-------------------------+
1 row in set (0.02 sec)mysql> USE cms;
Database changed
mysql> SELECT * FROM student;
+----+----------+-------+
| id | username | score |
+----+----------+-------+
|  1 | king     |    95 |
|  2 | king1    |    35 |
|  3 | king2    |    45 |
|  4 | king3    |    55 |
|  5 | king4    |    65 |
|  6 | king5    |    75 |
|  7 | king6    |    80 |
|  8 | king7    |    90 |
|  9 | king8    |    25 |
+----+----------+-------+
9 rows in set (0.00 sec)mysql> SELECT id,CONCAT(username,'_')FROM student;
+----+----------------------+
| id | CONCAT(username,'_') |
+----+----------------------+
|  1 | king_                |
|  2 | king1_               |
|  3 | king2_               |
|  4 | king3_               |
|  5 | king4_               |
|  6 | king5_               |
|  7 | king6_               |
|  8 | king7_               |
|  9 | king8_               |
+----+----------------------+
9 rows in set (0.00 sec)mysql> SELECT CONCAT('a','b',null);
+----------------------+
| CONCAT('a','b',null) |
+----------------------+
| NULL                 |
+----------------------+
1 row in set (0.00 sec)

3）CONTACT_WS(X, S1, S2…)：将制定分隔符连接字符串，当X为NULL时，连接结果为NULL，当S1或S2…为NULL时当做空字符处理

mysql> SELECT CONCAT_WS('^_^','a','b','c');
+------------------------------+
| CONCAT_WS('^_^','a','b','c') |
+------------------------------+
| a^_^b^_^c                    |
+------------------------------+
1 row in set (0.00 sec)mysql> SELECT CONCAT_WS('','a','b','c');
+---------------------------+
| CONCAT_WS('','a','b','c') |
+---------------------------+
| abc                       |
+---------------------------+
1 row in set (0.00 sec)mysql> SELECT CONCAT_WS(NULL,'a','b','c');
+-----------------------------+
| CONCAT_WS(NULL,'a','b','c') |
+-----------------------------+
| NULL                        |
+-----------------------------+
1 row in set (0.00 sec)mysql> SELECT CONCAT_WS('^_^','a','b','c',NULL);
+-----------------------------------+
| CONCAT_WS('^_^','a','b','c',NULL) |
+-----------------------------------+
| a^_^b^_^c                         |
+-----------------------------------+
1 row in set (0.00 sec)

4）UPPER(S)/UCASE(S)：将字符转换为大写

mysql> SELECT UPPER('this is a test'),UCASE('this is a test');
+-------------------------+-------------------------+
| UPPER('this is a test') | UCASE('this is a test') |
+-------------------------+-------------------------+
| THIS IS A TEST          | THIS IS A TEST          |
+-------------------------+-------------------------+
1 row in set (0.00 sec)

（5）LOWER(S)/LCASE(S)：将字符转换为小写

mysql> SELECT LOWER('HELLO WORLD'),LCASE('HELLO WORLD');
+----------------------+----------------------+
| LOWER('HELLO WORLD') | LCASE('HELLO WORLD') |
+----------------------+----------------------+
| hello world          | hello world          |
+----------------------+----------------------+
1 row in set (0.00 sec)

（6）LEFT(S, N)/RIGHT(S, N)：返回字符串的前/后n个字符

mysql> SELECT LEFT('ABCDEF',2),RIGHT('ABCDEF',2);
+------------------+-------------------+
| LEFT('ABCDEF',2) | RIGHT('ABCDEF',2) |
+------------------+-------------------+
| AB               | EF                |
+------------------+-------------------+
1 row in set (0.01 sec)

（7）LPAD(S1, LEN, S2)/ RPAD(S1, LEN, S2)：将字符串S1用S2填充到指定的LEN

mysql> SELECT LPAD('A',5,'?'),RPAD('A',5,'!');
+-----------------+-----------------+
| LPAD('A',5,'?') | RPAD('A',5,'!') |
+-----------------+-----------------+
| ????A           | A!!!!           |
+-----------------+-----------------+
1 row in set (0.04 sec)

（8）LTRIN(S)/ RTRIM(S)/ TRIM(S)：去掉字符串中的空格

mysql> SELECT CONCAT('_',TRIM(' ABC '),'_'),CONCAT('_',LTRIM(' ABC '),'_'),CONCAT('_',RTRIM(' ABC '),'_');
+-------------------------------+--------------------------------+--------------------------------+
| CONCAT('_',TRIM(' ABC '),'_') | CONCAT('_',LTRIM(' ABC '),'_') | CONCAT('_',RTRIM(' ABC '),'_') |
+-------------------------------+--------------------------------+--------------------------------+
| _ABC_                         | _ABC _                         | _ ABC_                         |
+-------------------------------+--------------------------------+--------------------------------+
1 row in set (0.00 sec)

（9）TRIM(S1 FROM S)：去掉字符串s中开始处和结尾处的字符串s1

mysql> SELECT TRIM('A' FROM 'ABCBCA');
+-------------------------+
| TRIM('A' FROM 'ABCBCA') |
+-------------------------+
| BCBC                    |
+-------------------------+
1 row in set (0.00 sec)

（10）REPEAT(S,N)：重复字符串指定次数

mysql> SELECT REPEAT('H',5);
+---------------+
| REPEAT('H',5) |
+---------------+
| HHHHH         |
+---------------+
1 row in set (0.00 sec)

（11）SPACE(N)：返回N个空格

mysql> SELECT CONCAT('_',SPACE(5),'_');
+--------------------------+
| CONCAT('_',SPACE(5),'_') |
+--------------------------+
| _     _                  |
+--------------------------+
1 row in set (0.00 sec)

（12）REPLACE(S,S1,S2)：在字符串中搜索S1，替换成S2（区分大小写，若未搜索到则返回原字符串）

mysql> SELECT REPLACE('ABCBCA','A','_');
+---------------------------+
| REPLACE('ABCBCA','A','_') |
+---------------------------+
| _BCBC_                    |
+---------------------------+
1 row in set (0.00 sec)mysql> SELECT REPLACE('ABCBCA','a','_');
+---------------------------+
| REPLACE('ABCBCA','a','_') |
+---------------------------+
| ABCBCA                    |
+---------------------------+
1 row in set (0.00 sec)

（13）STRCMP(S1, S2)：比较字符串，不区分大小写，>=<分别返回1，0，-1

mysql> SELECT STRCMP('A','A'),STRCMP('A','a'),STRCMP('B','A');
+-----------------+-----------------+-----------------+
| STRCMP('A','A') | STRCMP('A','a') | STRCMP('B','A') |
+-----------------+-----------------+-----------------+
|               0 |               0 |               1 |
+-----------------+-----------------+-----------------+
1 row in set (0.02 sec)mysql> SELECT STRCMP('A','A'),STRCMP('A','a'),STRCMP('A','B');
+-----------------+-----------------+-----------------+
| STRCMP('A','A') | STRCMP('A','a') | STRCMP('A','B') |
+-----------------+-----------------+-----------------+
|               0 |               0 |              -1 |
+-----------------+-----------------+-----------------+
1 row in set (0.00 sec)

（14）SUBSTRING(S, N, LEN)：截取字符串

mysql> SELECT SUBSTRING('ABCDEF',2,2);
+-------------------------+
| SUBSTRING('ABCDEF',2,2) |
+-------------------------+
| BC                      |
+-------------------------+
1 row in set (0.00 sec)

（15）REVERSE(S)：反转字符串

mysql> SELECT REVERSE('ABC');
+----------------+
| REVERSE('ABC') |
+----------------+
| CBA            |
+----------------+
1 row in set (0.00 sec)

（16）ELT(N, S1, S2)：返回指定位置的字符串

mysql> SELECT ELT(2,'A','B','C');
+--------------------+
| ELT(2,'A','B','C') |
+--------------------+
| B                  |
+--------------------+
1 row in set (0.00 sec)

日期时间函数



（1）CURDATE(), CURRENT_DATE()：返回当前日期

mysql> SELECT CURDATE(),CURRENT_DATE();
+------------+----------------+
| CURDATE()  | CURRENT_DATE() |
+------------+----------------+
| 2020-03-27 | 2020-03-27    |
+------------+----------------+
1 row in set (0.04 sec)

（2）CURTIME(), CURRENT_TIME()：返回当前时间

mysql> SELECT CURTIME(),CURRENT_TIME();
+-----------+----------------+
| CURTIME() | CURRENT_TIME() |
+-----------+----------------+
| 15:59:32  | 15:59:32       |
+-----------+----------------+
1 row in set (0.00 sec)

（3）NOW()：返回当前日期和时间

mysql> SELECT NOW();
+---------------------+
| NOW()               |
+---------------------+
| 2020-03-27 15:59:37 |
+---------------------+
1 row in set (0.00 sec)

（4）MONTH(D)：返回当前日期中月份的值

mysql> SELECT MONTH('2015-1-3');
+-------------------+
| MONTH('2015-3-27') |
+-------------------+
|                 3 |
+-------------------+
1 row in set (0.00 sec)mysql> SELECT MONTH(NOW());
+--------------+
| MONTH(NOW()) |
+--------------+
|            3 |
+--------------+
1 row in set (0.00 sec)

（5）MONTHNAME(D)：返回日期中月份名称

mysql> SELECT MONTHNAME(NOW());
+------------------+
| MONTHNAME(NOW()) |
+------------------+
| March            |
+------------------+
1 row in set (0.09 sec)

（6）DAYNAME(D)：返回日期是几

mysql> SELECT DAYNAME(NOW());
+----------------+
| DAYNAME(NOW()) |
+----------------+
| Friday       |
+----------------+
1 row in set (0.02 sec)

（7）DAYOFWEEK(D)：返回一周内的第几天，1代表星期日

mysql> SELECT DAYOFWEEK(NOW());
+------------------+
| DAYOFWEEK(NOW()) |
+------------------+
|                6 |
+------------------+
1 row in set (0.00 sec)

（8）WEEKDAY(D)：返回日期是星期几，0代表星期一

mysql> SELECT WEEKDAY(NOW());
+----------------+
| WEEKDAY(NOW()) |
+----------------+
|              6 |
+----------------+
1 row in set (0.00 sec)

（9）WEEK(D)：一年中的第几个星期

mysql> SELECT WEEK(NOW());
+-------------+
| WEEK(NOW()) |
+-------------+
|           14 |
+-------------+
1 row in set (0.00 sec)

（10）YEAR(D)：返回年份值

mysql> SELECT YEAR(NOW());
+-------------+
| YEAR(NOW()) |
+-------------+
|        2020 |
+-------------+
1 row in set (0.00 sec)

（11）HOUR(T)：返回小时值

mysql> SELECT HOUR(NOW());
+-------------+
| HOUR(NOW()) |
+-------------+
|          16 |
+-------------+
1 row in set (0.00 sec)

（12）MINUTE(T)：返回分钟值

mysql> SELECT MINUTE(NOW());
+---------------+
| MINUTE(NOW()) |
+---------------+
|             1 |
+---------------+
1 row in set (0.00 sec)

（13）SECOND(T)：返回秒数

mysql> SELECT SECOND(NOW());
+---------------+
| SECOND(NOW()) |
+---------------+
|            49 |
+---------------+
1 row in set (0.00 sec)

（14）DATEDIFF(D1, D2)：计算量日期之间相隔的天数

mysql> SELECT DATEDIFF(CURRENT_DATE(),'1990-1-1');
+-------------------------------------+
| DATEDIFF(CURRENT_DATE(),'1990-1-1') |
+-------------------------------------+
|                                9133 |
+-------------------------------------+
1 row in set (0.02 sec)

条件函数


（1）IF(EXPR, V1, V2)：如果表达式EXPR成立，则返回结果V1，否则返回V2

mysql> USE cms;
Database changed
mysql> SELECT * FROM student;
+----+----------+-------+
| id | username | score |
+----+----------+-------+
|  1 | king     |    95 |
|  2 | king1    |    35 |
|  3 | king2    |    45 |
|  4 | king3    |    55 |
|  5 | king4    |    65 |
|  6 | king5    |    75 |
|  7 | king6    |    80 |
|  8 | king7    |    90 |
|  9 | king8    |    25 |
+----+----------+-------+
9 rows in set (0.00 sec)mysql> SELECT id,username,score,IF(score>=60,'及格','不及格')FROM student;
+----+----------+-------+------------------------------------+
| id | username | score | IF(score>=60,'及格','不及格')      |
+----+----------+-------+------------------------------------+
|  1 | king     |    95 | 及格                               |
|  2 | king1    |    35 | 不及格                             |
|  3 | king2    |    45 | 不及格                             |
|  4 | king3    |    55 | 不及格                             |
|  5 | king4    |    65 | 及格                               |
|  6 | king5    |    75 | 及格                               |
|  7 | king6    |    80 | 及格                               |
|  8 | king7    |    90 | 及格                               |
|  9 | king8    |    25 | 不及格                             |
+----+----------+-------+------------------------------------+
9 rows in set (0.03 sec)

（2）IFNULL(V1,V2)：如果V1不为空，就显示V1的值，否则显示V2的值

mysql> SELECT id,username,age,IFNULL(age,'100')FROM cms_user;
+----+-----------+------+-------------------+
| id | username  | age  | IFNULL(age,'100') |
+----+-----------+------+-------------------+
|  1 | 张三      |   21 | 21                |
|  2 | 张三丰    |   31 | 31                |
|  3 | 章子怡    |   43 | 43                |
|  4 | long      |   41 | 41                |
|  5 | ring      |    9 | 9                 |
|  6 | queen     |   77 | 77                |
|  8 | blek      |   85 | 85                |
|  9 | rose      |    9 | 9                 |
| 10 | lily      |   39 | 39                |
| 11 | john      |   72 | 72                |
| 12 | test1     | NULL | 100               |
| 13 | TEST2     |   18 | 18                |
| 14 | lll       |   18 | 18                |
| 15 | ttt       |   18 | 18                |
| 16 | ooo       |   18 | 18                |
+----+-----------+------+-------------------+
15 rows in set (0.00 sec)

（3）CASE WHEN exp1 THEN vi [WHEN exp2 THEN v2] [ELSE vn] END

mysql> SELECT id,username,score, CASE WHEN score>60 THEN '不错' WHEN score=60 THEN '刚及格' ELSE '没及格' END FROM student;
+----+----------+-------+--------------------------------------------------------------------------------------+
| id | username | score | CASE WHEN score>60 THEN '不错' WHEN score=60 THEN '刚及格' ELSE '没及格' END         |
+----+----------+-------+--------------------------------------------------------------------------------------+
|  1 | king     |    95 | 不错                                                                                 |
|  2 | king1    |    35 | 没及格                                                                               |
|  3 | king2    |    45 | 没及格                                                                               |
|  4 | king3    |    55 | 没及格                                                                               |
|  5 | king4    |    65 | 不错                                                                                 |
|  6 | king5    |    75 | 不错                                                                                 |
|  7 | king6    |    80 | 不错                                                                                 |
|  8 | king7    |    90 | 不错                                                                                 |
|  9 | king8    |    25 | 没及格                                                                               |
+----+----------+-------+--------------------------------------------------------------------------------------+
9 rows in set (0.00 sec)

系统信息函数

加密函数


1）MD5(str)：信息摘要算法

mysql> SELECT MD5('ADMIN');
+----------------------------------+
| MD5('ADMIN')                     |
+----------------------------------+
| 73acd9a5972130b75066c82595a1fae3 |
+----------------------------------+
1 row in set (0.07 sec)
mysql> SELECT LENGTH(MD5('ADMIN'));
+----------------------+
| LENGTH(MD5('ADMIN')) |
+----------------------+
|                   32 |
+----------------------+
1 row in set (0.00 sec

)

（2）PASSWORD(str)：密码算法（例如对用户设置密码）

mysql> SELECT PASSWORD('root'),PASSWORD('king');
+-------------------------------------------+-------------------------------------------+
| PASSWORD('root')                          | PASSWORD('king')                          |
+-------------------------------------------+-------------------------------------------+
| *81F5E21E35407D884A6CD4A731AEBFB6AF209E1B | *0C6F8A2CE8ABFD18609CCE4CDFAB3C15DAD20718 |
+-------------------------------------------+-------------------------------------------+
1 row in set (0.02 sec)

（3）ENCODE(str, pwd_str)：加密结果是一二进制数，必须使用BLOB类型保存字段
（4）DECODE(crypt_str, pwd_str)：通过对ENCODE加密后的内容进行解密

其他常用函数


1）FORMAT(x, n)：将数字x进行格式化，并将x保留到小数点后n为

mysql> SELECT FORMAT(3.14567,2);
+-------------------+
| FORMAT(3.14567,2) |
+-------------------+
| 3.15              |
+-------------------+
1 row in set (0.00 sec)

（2）ASCII(s)：返回字符串的第一个字符的ASCII码

mysql> SELECT ASCII('abc');
+--------------+
| ASCII('abc') |
+--------------+
|           97 |
+--------------+
1 row in set (0.02 sec)

（3）BIN(x)：返回x的二进制编码，HEX(x)：返回x的十六进制编码，OCT(x)：返回x的八进制编码

mysql> SELECT BIN(5),HEX(5),OCT(5);
+--------+--------+--------+
| BIN(5) | HEX(5) | OCT(5) |
+--------+--------+--------+
| 101    | 5      | 5      |
+--------+--------+--------+
1 row in set (0.02 sec)

（4）CONV(x, f1, f2)：将x从f1进制数编程f2进制数

mysql> SELECT CONV(5,10,2);
+--------------+
| CONV(5,10,2) |
+--------------+
| 101          |
+--------------+
1 row in set (0.00 sec)mysql> SELECT CONV(35,10,2);
+---------------+
| CONV(35,10,2) |
+---------------+
| 100011        |
+---------------+
1 row in set (0.00 sec)mysql> SELECT CONV(35,10,8);
+---------------+
| CONV(35,10,8) |
+---------------+
| 43            |
+---------------+
1 row in set (0.00 sec)mysql> SELECT CONV(35,10,16);
+----------------+
| CONV(35,10,16) |
+----------------+
| 23             |
+----------------+
1 row in set (0.00 sec)

（5）INET_ATON(IP)：将IP地址转换为数字

mysql> SELECT INET_ATON('127.0.0.1');
+------------------------+
| INET_ATON('127.0.0.1') |
+------------------------+
|             2130706433 |
+------------------------+
1 row in set (0.06 sec)

（6）INET_NTOA(n)：将数字转换成IP地址

mysql> SELECT INET_NTOA(2130706433);
+-----------------------+
| INET_NTOA(2130706433) |
+-----------------------+
| 127.0.0.1             |
+-----------------------+
1 row in set (0.02 sec)

（7）get_LOCT(name, time)：定义锁

mysql> SELECT GET_LOCK('KING',10);
+---------------------+
| GET_LOCK('KING',10) |
+---------------------+
|                   1 |
+---------------------+
1 row in set (0.05 sec)

（8）IS_FREE_LOCK(name)：判断锁是否正在使用，0表示正在使用，1表示未在使用，解锁或新建立锁都能使锁脱离被使用的状态

mysql> SELECT IS_FREE_LOCK('KING');
+----------------------+
| IS_FREE_LOCK('KING') |
+----------------------+
|                    0 |
+----------------------+
1 row in set (0.02 sec)mysql> SELECT RELEASE_LOCK('KING');
+----------------------+
| RELEASE_LOCK('KING') |
+----------------------+
|                    1 |
+----------------------+
1 row in set (0.00 sec)mysql> SELECT IS_FREE_LOCK('KING');
+----------------------+
| IS_FREE_LOCK('KING') |
+----------------------+
|                    1 |
+----------------------+
1 row in set (0.00 sec)mysql> SELECT GET_LOCK('MAIZI',10);
+----------------------+
| GET_LOCK('MAIZI',10) |
+----------------------+
|                    1 |
+----------------------+
1 row in set (0.00 sec)mysql> SELECT IS_FREE_LOCK('MAIZI');
+-----------------------+
| IS_FREE_LOCK('MAIZI') |
+-----------------------+
|                     0 |
+-----------------------+
1 row in set (0.00 sec)mysql> SELECT GET_LOCK('AB',5);
+------------------+
| GET_LOCK('AB',5) |
+------------------+
|                1 |
+------------------+
1 row in set (0.00 sec)mysql> SELECT IS_FREE_LOCK('MAIZI');
+-----------------------+
| IS_FREE_LOCK('MAIZI') |
+-----------------------+
|                     1 |
+-----------------------+
1 row in set (0.00 sec)

（9）RELSASE_LOCK(name)：解锁

mysql> SELECT RELEASE_LOCK('KING');
+----------------------+
| RELEASE_LOCK('KING') |
+----------------------+
|                    1 |
+----------------------+
1 row in set (0.00 sec)mysql> SELECT IS_FREE_LOCK('KING');
+----------------------+
| IS_FREE_LOCK('KING') |
+----------------------+
|                    1 |
+----------------------+
1 row in set (0.00 sec)

MySQL索引

索引的概念

（1）索引由数据库中的一列或多列组合而成，其作用是提高对表中数据的查询速度
（2）索引的优点是可以提高检索数据的速度
（3）索引的缺点是创建和维护索引需要耗费时间
（4）索引可以提高查询速度，会减慢写入速度

索引的分类

（1）普通索引
（2）唯一索引
（3）全文索引
只有是字符类型且全是英文名时可使用
（4）单列索引
（5）多列索引
（6）空间索引

创建索引

创建表时创建索引

CREATE TABLE tbl_name(
字段名称 字段类型 [完整性约束条件], …, [UNIQUE | FULLTEXT | SPATIAL] INDEX | KEY [索引名称] (字段名称)
)
（1）创建普通索引

mysql> CREATE TABLE test4(-> id TINYINT UNSIGNED,-> username VARCHAR(20),-> INDEX in_id(id),-> KEY in_username(username)-> );
Query OK, 0 rows affected (0.42 sec)mysql> SHOW CREATE TABLE test4;
+-------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table                                                                                                                                                                                       |
+-------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| test4 | CREATE TABLE `test4` (`id` tinyint(3) unsigned DEFAULT NULL,`username` varchar(20) DEFAULT NULL,KEY `in_id` (`id`),KEY `in_username` (`username`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 |
+-------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.03 sec)

（2）创建唯一索引

mysql> CREATE TABLE test5(-> id TINYINT UNSIGNED AUTO_INCREMENT KEY,-> username VARCHAR(20) NOT NULL UNIQUE,-> card CHAR(18) NOT NULL,-> UNIQUE KEY uni_card(card)-> );
Query OK, 0 rows affected (0.47 sec)mysql> SHOW CREATE TABLE test5;
+-------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table                                                                                                                                                                                                                                                                |
+-------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| test5 | CREATE TABLE `test5` (`id` tinyint(3) unsigned NOT NULL AUTO_INCREMENT,`username` varchar(20) NOT NULL,`card` char(18) NOT NULL,PRIMARY KEY (`id`),UNIQUE KEY `username` (`username`),UNIQUE KEY `uni_card` (`card`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 |
+-------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

（3）创建全文索引

mysql> CREATE TABLE test6(-> id TINYINT UNSIGNED AUTO_INCREMENT KEY,-> username VARCHAR(20) NOT NULL UNIQUE,-> userDesc VARCHAR(20) NOT NULL,-> FULLTEXT INDEX full_userDesc(userDesc)-> );
Query OK, 0 rows affected (2.09 sec)mysql> SHOW CREATE TABLE test6;
+-------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table                                                                                                                                                                                                                                                                                  |
+-------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| test6 | CREATE TABLE `test6` (`id` tinyint(3) unsigned NOT NULL AUTO_INCREMENT,`username` varchar(20) NOT NULL,`userDesc` varchar(20) NOT NULL,PRIMARY KEY (`id`),UNIQUE KEY `username` (`username`),FULLTEXT KEY `full_userDesc` (`userDesc`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 |
+-------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

（4）创建单列索引

mysql> CREATE TABLE test7(-> id TINYINT UNSIGNED AUTO_INCREMENT KEY,-> test1 VARCHAR(20) NOT NULL,-> test2 VARCHAR(20) NOT NULL,-> test3 VARCHAR(20) NOT NULL,-> test4 VARCHAR(20) NOT NULL,-> INDEX in_test1(test1)-> );
Query OK, 0 rows affected (0.38 sec)mysql> SHOW CREATE TABLE test7;
+-------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table                                                                                                                                                                                                                                                                                     |
+-------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| test7 | CREATE TABLE `test7` (`id` tinyint(3) unsigned NOT NULL AUTO_INCREMENT,`test1` varchar(20) NOT NULL,`test2` varchar(20) NOT NULL,`test3` varchar(20) NOT NULL,`test4` varchar(20) NOT NULL,PRIMARY KEY (`id`),KEY `in_test1` (`test1`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 |
+-------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.02 sec)

（5）创建多列索引

mysql> CREATE TABLE test8(-> id TINYINT UNSIGNED AUTO_INCREMENT KEY,-> test1 VARCHAR(20) NOT NULL,-> test2 VARCHAR(20) NOT NULL,-> test3 VARCHAR(20) NOT NULL,-> test4 VARCHAR(20) NOT NULL,-> INDEX mul_t1_t2_t3(test1,test2,test3)-> );
Query OK, 0 rows affected (0.27 sec)mysql> SHOW CREATE TABLE test8;
+-------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table                                                                                                                                                                                                                                                                                                         |
+-------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| test8 | CREATE TABLE `test8` (`id` tinyint(3) unsigned NOT NULL AUTO_INCREMENT,`test1` varchar(20) NOT NULL,`test2` varchar(20) NOT NULL,`test3` varchar(20) NOT NULL,`test4` varchar(20) NOT NULL,PRIMARY KEY (`id`),KEY `mul_t1_t2_t3` (`test1`,`test2`,`test3`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 |
+-------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)mysql> DESC test8;
+-------+---------------------+------+-----+---------+----------------+
| Field | Type                | Null | Key | Default | Extra          |
+-------+---------------------+------+-----+---------+----------------+
| id    | tinyint(3) unsigned | NO   | PRI | NULL    | auto_increment |
| test1 | varchar(20)         | NO   | MUL | NULL    |                |
| test2 | varchar(20)         | NO   |     | NULL    |                |
| test3 | varchar(20)         | NO   |     | NULL    |                |
| test4 | varchar(20)         | NO   |     | NULL    |                |
+-------+---------------------+------+-----+---------+----------------+
5 rows in set (0.08 sec)

（6）创建空间索引（只能给空间变量创建空间索引）

mysql> CREATE TABLE test10(-> id TINYINT UNSIGNED AUTO_INCREMENT KEY,-> test GEOMETRY NOT NULL,-> SPATIAL INDEX spa_test(test)-> )ENGINE=MyISAM;
Query OK, 0 rows affected (0.06 sec)mysql> SHOW CREATE TABLE test10;
+--------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table  | Create Table                                                                                                                                                                                         |
+--------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| test10 | CREATE TABLE `test10` (`id` tinyint(3) unsigned NOT NULL AUTO_INCREMENT,`test` geometry NOT NULL,PRIMARY KEY (`id`),SPATIAL KEY `spa_test` (`test`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8 |
+--------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.09 sec)

在已经存在的表上创建索引

【1】CREATE [UNIQUE | FULLTEXT | SPATIAL] INDEX 索引名称 ON 表名 {字段名称 [(长度)] [ASC|DESC]}
（1）普通索引

CREATE INDEX in_id ON test4(id)

（2）唯一索引

CREATE UNIQUE INDEX uni_username ON test5(username);

（3）全文索引
（4）单列索引
（5）多列索引
（6）空间索引

CREATE SPATIAL INDEX spa_test ON test10(test);

【2】ALTER TABLE tbl_name ADD [UNIQUE | FULLTEXT | SPATIAL] INDEX 索引名称(字段名称[(长度)] [ASC|DESC])
（1）普通索引

ALTER TABLE test4 ADD INDEX in_username(username)

（2）唯一索引

ALTER TABLE test5 ADD UNIQUE INDEX uni_card(card);

（3）全文索引

CREATE FULLTEXT INDEX full_userDesc ON test6(userDesc);

（4）单列索引
（5）多列索引

ALTER TABLE test8 ADD INDEX mul_ti_t2_t3(test1,test2,test3);

（6）空间索引

删除索引

【1】DROP INDEX 索引名称 ON tbl_name

DROP INDEX full_userDesc ON test6;

【2】ALTER tbl_name 表名 DROP INDEX 索引名称

ALTER TABLE test8 DROP INDEX mul_t1_t2_t3;

MySQL图形化管理工具

PHPMyAdmin

PHPMyAdmin是一个用PHP编写的软件工具，可以通过web方式控制和操作MySQL数据库

SQLyog

【1】是业界注明的Webyog公司出品的一款简介高效，功能强大的MySQL数据库管理工具
【2】特点：
（1）基于C++和MySQLQPI编程
（2）方便快捷的数据库同步与数据库结构同步工具
（3）易用的数据库，数据备份与还原功能（4）支持导入与导出XML、HTML、CSV等多种格式的数据
（5）直接运行批量SQL脚本文件，速度极快
（6）新版本更适合增加了强大的数据迁移

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