查询-非等值连接,外连接,子查询
非等值连接
创建一张表
mysql> create table wage_grade
-> (
-> id int,
-> grade char(1),
-> low int,
-> high int,
-> primary key(id));
Query OK, 0 rows affected (0.00 sec)
查看表
mysql> show tables;
+-------------------+
| Tables_in_nsd2021 |
+-------------------+
| departments |
| employees |
| salary |
| wage_grade |
+-------------------+
4 rows in set (0.00 sec)
向表中插入数据
mysql> insert into wage_grade values
-> (1,'A',5000,8000),
-> (2,'B',8001,10000),
-> (3,'C',10001,15000),
-> (4,'D',15001,20000),
-> (5,'E',20001,1000000);
Query OK, 5 rows affected (0.00 sec)
Records: 5 Duplicates: 0 Warnings: 0
查看表中数据
mysql> select
-> *
-> from wage_grade;
+----+-------+-------+---------+
| id | grade | low | high |
+----+-------+-------+---------+
| 1 | A | 5000 | 8000 |
| 2 | B | 8001 | 10000 |
| 3 | C | 10001 | 15000 |
| 4 | D | 15001 | 20000 |
| 5 | E | 20001 | 1000000 |
+----+-------+-------+---------+
5 rows in set (0.00 sec)
查询2018年员工基本工资级别
mysql> select
-> employee_id,date,basic,bonus,grade
-> from salary
-> inner join wage_grade
-> on basic between low and high
-> where year(date)=2018 and month(date)=12
-> order by grade;
+-------------+------------+-------+-------+-------+
| employee_id | date | basic | bonus | grade |
+-------------+------------+-------+-------+-------+
| 51 | 2018-12-10 | 6076 | 1000 | A |
| 97 | 2018-12-10 | 7292 | 1000 | A |
| 133 | 2018-12-10 | 6076 | 7000 | A |
| 87 | 2018-12-10 | 7292 | 5000 | A |
| 111 | 2018-12-10 | 6076 | 3000 | A |
| 64 | 2018-12-10 | 6076 | 2000 | A |
| 89 | 2018-12-10 | 7292 | 5000 | A |
| 30 | 2018-12-10 | 7292 | 8000 | A |
| 55 | 2018-12-10 | 6076 | 5000 | A |
| 90 | 2018-12-10 | 6076 | 1000 | A |
| 101 | 2018-12-10 | 7292 | 9000 | A |
| 114 | 2018-12-10 | 6076 | 3000 | A |
| 18 | 2018-12-10 | 7292 | 2000 | A |
| 83 | 2018-12-10 | 9724 | 1000 | B |
| 130 | 2018-12-10 | 9724 | 11000 | B |
| 26 | 2018-12-10 | 8507 | 5000 | B |
| 109 | 2018-12-10 | 8507 | 11000 | B |
| 3 | 2018-12-10 | 9724 | 8000 | B |
| 121 | 2018-12-10 | 9724 | 7000 | B |
| 41 | 2018-12-10 | 9724 | 9000 | B |
| 77 | 2018-12-10 | 8507 | 11000 | B |
| 67 | 2018-12-10 | 9724 | 9000 | B |
| 82 | 2018-12-10 | 8507 | 8000 | B |
| 116 | 2018-12-10 | 9724 | 11000 | B |
| 93 | 2018-12-10 | 8507 | 2000 | B |
| 69 | 2018-12-10 | 13369 | 4000 | C |
| 22 | 2018-12-10 | 14585 | 1000 | C |
| 59 | 2018-12-10 | 10938 | 6000 | C |
| 94 | 2018-12-10 | 14585 | 6000 | C |
| 129 | 2018-12-10 | 14585 | 7000 | C |
| 70 | 2018-12-10 | 12154 | 3000 | C |
| 84 | 2018-12-10 | 10938 | 7000 | C |
| 60 | 2018-12-10 | 13369 | 10000 | C |
| 72 | 2018-12-10 | 13369 | 4000 | C |
| 50 | 2018-12-10 | 10938 | 6000 | C |
| 96 | 2018-12-10 | 14585 | 11000 | C |
| 132 | 2018-12-10 | 10938 | 11000 | C |
| 39 | 2018-12-10 | 14585 | 5000 | C |
| 120 | 2018-12-10 | 10938 | 3000 | C |
| 74 | 2018-12-10 | 12154 | 8000 | C |
| 14 | 2018-12-10 | 12154 | 5000 | C |
| 15 | 2018-12-10 | 10938 | 10000 | C |
| 43 | 2018-12-10 | 13369 | 5000 | C |
| 65 | 2018-12-10 | 14585 | 9000 | C |
| 100 | 2018-12-10 | 14585 | 11000 | C |
| 44 | 2018-12-10 | 13369 | 6000 | C |
| 78 | 2018-12-10 | 10938 | 10000 | C |
| 113 | 2018-12-10 | 10938 | 1000 | C |
| 124 | 2018-12-10 | 14585 | 9000 | C |
| 45 | 2018-12-10 | 14585 | 10000 | C |
| 115 | 2018-12-10 | 13369 | 7000 | C |
| 126 | 2018-12-10 | 10938 | 11000 | C |
| 9 | 2018-12-10 | 13369 | 2000 | C |
| 47 | 2018-12-10 | 13369 | 8000 | C |
| 58 | 2018-12-10 | 13369 | 11000 | C |
| 107 | 2018-12-10 | 18231 | 7000 | D |
| 11 | 2018-12-10 | 17016 | 8000 | D |
| 49 | 2018-12-10 | 15800 | 9000 | D |
| 95 | 2018-12-10 | 19448 | 8000 | D |
| 1 | 2018-12-10 | 17016 | 7000 | D |
| 108 | 2018-12-10 | 18231 | 2000 | D |
| 12 | 2018-12-10 | 15800 | 4000 | D |
| 85 | 2018-12-10 | 15800 | 1000 | D |
| 73 | 2018-12-10 | 17016 | 10000 | D |
| 13 | 2018-12-10 | 18231 | 3000 | D |
| 62 | 2018-12-10 | 15800 | 4000 | D |
| 110 | 2018-12-10 | 18231 | 2000 | D |
| 52 | 2018-12-10 | 19448 | 9000 | D |
| 28 | 2018-12-10 | 17016 | 9000 | D |
| 63 | 2018-12-10 | 15800 | 8000 | D |
| 98 | 2018-12-10 | 19448 | 9000 | D |
| 4 | 2018-12-10 | 17016 | 2000 | D |
| 99 | 2018-12-10 | 15800 | 5000 | D |
| 5 | 2018-12-10 | 17016 | 3000 | D |
| 123 | 2018-12-10 | 19448 | 10000 | D |
| 6 | 2018-12-10 | 17016 | 1000 | D |
| 17 | 2018-12-10 | 19448 | 7000 | D |
| 66 | 2018-12-10 | 19448 | 7000 | D |
| 79 | 2018-12-10 | 15800 | 4000 | D |
| 125 | 2018-12-10 | 17016 | 5000 | D |
| 32 | 2018-12-10 | 18231 | 11000 | D |
| 46 | 2018-12-10 | 15800 | 7000 | D |
| 81 | 2018-12-10 | 17016 | 3000 | D |
| 20 | 2018-12-10 | 19448 | 3000 | D |
| 92 | 2018-12-10 | 19448 | 2000 | D |
| 21 | 2018-12-10 | 18231 | 11000 | D |
| 127 | 2018-12-10 | 17016 | 6000 | D |
| 34 | 2018-12-10 | 23093 | 1000 | E |
| 106 | 2018-12-10 | 23093 | 5000 | E |
| 10 | 2018-12-10 | 21878 | 8000 | E |
| 48 | 2018-12-10 | 25524 | 1000 | E |
| 117 | 2018-12-10 | 25524 | 11000 | E |
| 37 | 2018-12-10 | 24309 | 4000 | E |
| 118 | 2018-12-10 | 23093 | 3000 | E |
| 25 | 2018-12-10 | 23093 | 3000 | E |
| 38 | 2018-12-10 | 23093 | 3000 | E |
| 119 | 2018-12-10 | 23093 | 10000 | E |
| 61 | 2018-12-10 | 24309 | 3000 | E |
| 2 | 2018-12-10 | 20662 | 9000 | E |
| 86 | 2018-12-10 | 24309 | 4000 | E |
| 27 | 2018-12-10 | 24309 | 5000 | E |
| 40 | 2018-12-10 | 20662 | 2000 | E |
| 76 | 2018-12-10 | 20662 | 11000 | E |
| 53 | 2018-12-10 | 25524 | 8000 | E |
| 88 | 2018-12-10 | 20662 | 2000 | E |
| 122 | 2018-12-10 | 21878 | 2000 | E |
| 29 | 2018-12-10 | 23093 | 1000 | E |
| 112 | 2018-12-10 | 24309 | 9000 | E |
| 16 | 2018-12-10 | 21878 | 8000 | E |
| 54 | 2018-12-10 | 21878 | 9000 | E |
| 31 | 2018-12-10 | 25524 | 9000 | E |
| 7 | 2018-12-10 | 23093 | 4000 | E |
| 56 | 2018-12-10 | 23093 | 3000 | E |
| 91 | 2018-12-10 | 20662 | 11000 | E |
| 102 | 2018-12-10 | 23093 | 3000 | E |
| 8 | 2018-12-10 | 23093 | 2000 | E |
| 57 | 2018-12-10 | 23093 | 3000 | E |
| 33 | 2018-12-10 | 23093 | 6000 | E |
| 68 | 2018-12-10 | 25524 | 9000 | E |
| 105 | 2018-12-10 | 21878 | 8000 | E |
+-------------+------------+-------+-------+-------+
120 rows in set (0.03 sec)
查询2018年员工基本工资各级别的人数
mysql> select
-> grade,count(*)
-> from salary
-> inner join wage_grade
-> on basic between low and high
-> where year(date)=2018 and month(date)=12
-> group by grade;
+-------+----------+
| grade | count(*) |
+-------+----------+
| A | 13 |
| B | 12 |
| C | 30 |
| D | 32 |
| E | 33 |
+-------+----------+
5 rows in set (0.01 sec)
查询2018年员工基本工资级别工资姓名
mysql> select
-> s.employee_id,name,date,basic,bonus,grade
-> from salary as s
-> inner join wage_grade
-> on basic between low and high
-> inner join employees as e
-> on e.employee_id=s.employee_id
-> where year(date)=2018 and month(date)=12
-> order by grade;
+-------------+-----------+------------+-------+-------+-------+
| employee_id | name | date | basic | bonus | grade |
+-------------+-----------+------------+-------+-------+-------+
| 51 | 吴静 | 2018-12-10 | 6076 | 1000 | A |
| 55 | 梁静 | 2018-12-10 | 6076 | 5000 | A |
| 90 | 莫凤兰 | 2018-12-10 | 6076 | 1000 | A |
| 18 | 戴璐 | 2018-12-10 | 7292 | 2000 | A |
| 64 | 徐金凤 | 2018-12-10 | 6076 | 2000 | A |
| 87 | 田萍 | 2018-12-10 | 7292 | 5000 | A |
| 30 | 邢淑兰 | 2018-12-10 | 7292 | 8000 | A |
| 114 | 黄秀云 | 2018-12-10 | 6076 | 3000 | A |
| 89 | 唐芳 | 2018-12-10 | 7292 | 5000 | A |
| 97 | 崔志强 | 2018-12-10 | 7292 | 1000 | A |
| 101 | 李柳 | 2018-12-10 | 7292 | 9000 | A |
| 111 | 赵凤兰 | 2018-12-10 | 6076 | 3000 | A |
| 133 | 杨金凤 | 2018-12-10 | 6076 | 7000 | A |
| 67 | 潘玲 | 2018-12-10 | 9724 | 9000 | B |
| 77 | 吴丽娟 | 2018-12-10 | 8507 | 11000 | B |
| 82 | 韩丹 | 2018-12-10 | 8507 | 8000 | B |
| 116 | 贾荣 | 2018-12-10 | 9724 | 11000 | B |
| 83 | 蒋秀芳 | 2018-12-10 | 9724 | 1000 | B |
| 109 | 巫杨 | 2018-12-10 | 8507 | 11000 | B |
| 121 | 孙婷 | 2018-12-10 | 9724 | 7000 | B |
| 130 | 王玉兰 | 2018-12-10 | 9724 | 11000 | B |
| 3 | 李玉英 | 2018-12-10 | 9724 | 8000 | B |
| 26 | 党丽 | 2018-12-10 | 8507 | 5000 | B |
| 41 | 陈玉 | 2018-12-10 | 9724 | 9000 | B |
| 93 | 余春梅 | 2018-12-10 | 8507 | 2000 | B |
| 9 | 张建平 | 2018-12-10 | 13369 | 2000 | C |
| 22 | 吕刚 | 2018-12-10 | 14585 | 1000 | C |
| 43 | 王波 | 2018-12-10 | 13369 | 5000 | C |
| 47 | 黄建平 | 2018-12-10 | 13369 | 8000 | C |
| 59 | 钟倩 | 2018-12-10 | 10938 | 6000 | C |
| 72 | 赵杰 | 2018-12-10 | 13369 | 4000 | C |
| 94 | 熊东 | 2018-12-10 | 14585 | 6000 | C |
| 120 | 段杨 | 2018-12-10 | 10938 | 3000 | C |
| 124 | 李慧 | 2018-12-10 | 14585 | 9000 | C |
| 129 | 汤华 | 2018-12-10 | 14585 | 7000 | C |
| 14 | 廖娜 | 2018-12-10 | 12154 | 5000 | C |
| 39 | 张倩 | 2018-12-10 | 14585 | 5000 | C |
| 44 | 黄文 | 2018-12-10 | 13369 | 6000 | C |
| 60 | 贺磊 | 2018-12-10 | 13369 | 10000 | C |
| 78 | 张娜 | 2018-12-10 | 10938 | 10000 | C |
| 113 | 杨桂香 | 2018-12-10 | 10938 | 1000 | C |
| 15 | 窦红梅 | 2018-12-10 | 10938 | 10000 | C |
| 45 | 陈刚 | 2018-12-10 | 14585 | 10000 | C |
| 65 | 张淑英 | 2018-12-10 | 14585 | 9000 | C |
| 69 | 谢莹 | 2018-12-10 | 13369 | 4000 | C |
| 74 | 赵成 | 2018-12-10 | 12154 | 8000 | C |
| 84 | 朱文 | 2018-12-10 | 10938 | 7000 | C |
| 96 | 胡瑜 | 2018-12-10 | 14585 | 11000 | C |
| 100 | 马涛 | 2018-12-10 | 14585 | 11000 | C |
| 126 | 谢琴 | 2018-12-10 | 10938 | 11000 | C |
| 132 | 刘倩 | 2018-12-10 | 10938 | 11000 | C |
| 50 | 臧龙 | 2018-12-10 | 10938 | 6000 | C |
| 58 | 张伟 | 2018-12-10 | 13369 | 11000 | C |
| 70 | 傅雪 | 2018-12-10 | 12154 | 3000 | C |
| 115 | 陈建军 | 2018-12-10 | 13369 | 7000 | C |
| 1 | 梁伟 | 2018-12-10 | 17016 | 7000 | D |
| 5 | 郑静 | 2018-12-10 | 17016 | 3000 | D |
| 13 | 王楠 | 2018-12-10 | 18231 | 3000 | D |
| 17 | 陈阳 | 2018-12-10 | 19448 | 7000 | D |
| 28 | 郑秀珍 | 2018-12-10 | 17016 | 9000 | D |
| 32 | 冯建国 | 2018-12-10 | 18231 | 11000 | D |
| 63 | 王玉华 | 2018-12-10 | 15800 | 8000 | D |
| 98 | 李莹 | 2018-12-10 | 19448 | 9000 | D |
| 108 | 宋艳 | 2018-12-10 | 18231 | 2000 | D |
| 6 | 牛建军 | 2018-12-10 | 17016 | 1000 | D |
| 52 | 张冬梅 | 2018-12-10 | 19448 | 9000 | D |
| 73 | 王璐 | 2018-12-10 | 17016 | 10000 | D |
| 95 | 毛丹 | 2018-12-10 | 19448 | 8000 | D |
| 99 | 王畅 | 2018-12-10 | 15800 | 5000 | D |
| 125 | 李静 | 2018-12-10 | 17016 | 5000 | D |
| 11 | 郭兰英 | 2018-12-10 | 17016 | 8000 | D |
| 20 | 蒋红 | 2018-12-10 | 19448 | 3000 | D |
| 49 | 李平 | 2018-12-10 | 15800 | 9000 | D |
| 79 | 叶欣 | 2018-12-10 | 15800 | 4000 | D |
| 92 | 陶红 | 2018-12-10 | 19448 | 2000 | D |
| 110 | 萧秀华 | 2018-12-10 | 18231 | 2000 | D |
| 4 | 张健 | 2018-12-10 | 17016 | 2000 | D |
| 12 | 王英 | 2018-12-10 | 15800 | 4000 | D |
| 21 | 曹宁 | 2018-12-10 | 18231 | 11000 | D |
| 46 | 罗建华 | 2018-12-10 | 15800 | 7000 | D |
| 62 | 林刚 | 2018-12-10 | 15800 | 4000 | D |
| 66 | 罗岩 | 2018-12-10 | 19448 | 7000 | D |
| 81 | 徐成 | 2018-12-10 | 17016 | 3000 | D |
| 85 | 刘玲 | 2018-12-10 | 15800 | 1000 | D |
| 107 | 游静 | 2018-12-10 | 18231 | 7000 | D |
| 123 | 许欣 | 2018-12-10 | 19448 | 10000 | D |
| 127 | 李瑞 | 2018-12-10 | 17016 | 6000 | D |
| 38 | 曹凯 | 2018-12-10 | 23093 | 3000 | E |
| 86 | 张宇 | 2018-12-10 | 24309 | 4000 | E |
| 102 | 张亮 | 2018-12-10 | 23093 | 3000 | E |
| 112 | 田兰英 | 2018-12-10 | 24309 | 9000 | E |
| 2 | 郭岩 | 2018-12-10 | 20662 | 9000 | E |
| 10 | 郭娟 | 2018-12-10 | 21878 | 8000 | E |
| 25 | 邵佳 | 2018-12-10 | 23093 | 3000 | E |
| 29 | 胡秀云 | 2018-12-10 | 23093 | 1000 | E |
| 33 | 曹杰 | 2018-12-10 | 23093 | 6000 | E |
| 48 | 范秀英 | 2018-12-10 | 25524 | 1000 | E |
| 56 | 陈洁 | 2018-12-10 | 23093 | 3000 | E |
| 68 | 柴冬梅 | 2018-12-10 | 25524 | 9000 | E |
| 91 | 李建华 | 2018-12-10 | 20662 | 11000 | E |
| 105 | 王小红 | 2018-12-10 | 21878 | 8000 | E |
| 117 | 和林 | 2018-12-10 | 25524 | 11000 | E |
| 7 | 刘斌 | 2018-12-10 | 23093 | 4000 | E |
| 34 | 苗桂花 | 2018-12-10 | 23093 | 1000 | E |
| 40 | 王淑珍 | 2018-12-10 | 20662 | 2000 | E |
| 53 | 邢成 | 2018-12-10 | 25524 | 8000 | E |
| 57 | 许辉 | 2018-12-10 | 23093 | 3000 | E |
| 61 | 沈秀梅 | 2018-12-10 | 24309 | 3000 | E |
| 88 | 田英 | 2018-12-10 | 20662 | 2000 | E |
| 106 | 苏波 | 2018-12-10 | 23093 | 5000 | E |
| 118 | 宋慧 | 2018-12-10 | 23093 | 3000 | E |
| 122 | 区军 | 2018-12-10 | 21878 | 2000 | E |
| 8 | 汪云 | 2018-12-10 | 23093 | 2000 | E |
| 16 | 聂想 | 2018-12-10 | 21878 | 8000 | E |
| 27 | 梁勇 | 2018-12-10 | 24309 | 5000 | E |
| 31 | 刘海燕 | 2018-12-10 | 25524 | 9000 | E |
| 37 | 朱淑兰 | 2018-12-10 | 24309 | 4000 | E |
| 54 | 孙丹 | 2018-12-10 | 21878 | 9000 | E |
| 76 | 刘桂兰 | 2018-12-10 | 20662 | 11000 | E |
| 119 | 张梅 | 2018-12-10 | 23093 | 10000 | E |
+-------------+-----------+------------+-------+-------+-------+
120 rows in set (0.01 sec)
查询生日与入职月份相同的员工
mysql> select
-> e.name,e.birth_date,em.hire_date
-> from employees as e
-> inner join employees as em
-> on month(e.birth_date)=month(em.hire_date)
-> and e.employee_id=em.employee_id;
+-----------+------------+------------+
| name | birth_date | hire_date |
+-----------+------------+------------+
| 李玉英 | 1974-01-25 | 2012-01-19 |
| 郑静 | 1997-02-14 | 2018-02-03 |
| 林刚 | 1990-09-23 | 2007-09-19 |
| 刘桂兰 | 1982-10-11 | 2003-10-14 |
| 张亮 | 1996-08-25 | 2015-08-10 |
| 许欣 | 1982-09-25 | 2011-09-09 |
| 王荣 | 1999-11-22 | 2019-11-14 |
+-----------+------------+------------+
7 rows in set (0.00 sec)
外连接
left join左连接,左边是主表
mysql> select
-> d.dept_id,dept_name,name
-> from departments as d
-> left outer join employees as e
-> on d.dept_id=e.dept_id;
+---------+-----------+-----------+
| dept_id | dept_name | name |
+---------+-----------+-----------+
| 1 | 人事部 | 梁伟 |
。。。。。。。。。。。
| 8 | 法务部 | 杨金凤 |
| 9 | NULL | NULL |
+---------+-----------+-----------+
134 rows in set (0.00 sec)
right join右连接,右边是主表
mysql> select d.dept_id,dept_name,name
-> from departments as d
-> right outer join employees as e
-> on d.dept_id=e.dept_id;
+---------+-----------+-----------+
| dept_id | dept_name | name |
+---------+-----------+-----------+
| 1 | 人事部 | 梁伟 |
。。。。。。。。。。。
| 8 | 法务部 | 杨金凤 |
+---------+-----------+-----------+
133 rows in set (0.00 sec)
子查询
select之后:仅支持单行单列
from之后:支持多行多列
where或having之后:支持单行单列、单行多列、多行单列
查询运维部所有员工信息
mysql> select *from employees where dept_id=(
select dept_id from departments where dept_name='运维部');
+-------------+-----------+------------+------------+--------------------+--------------+---------+
| employee_id | name | hire_date | birth_date | email | phone_number | dept_id |
+-------------+-----------+------------+------------+--------------------+--------------+---------+
| 14 | 廖娜 | 2012-05-20 | 1982-06-22 | liaona@tarena.com | 15827928192 | 3 |
| 15 | 窦红梅 | 2018-03-16 | 1971-09-09 | douhongmei@tedu.cn | 15004739483 | 3 |
| 16 | 聂想 | 2018-09-09 | 1999-06-05 | niexiang@tedu.cn | 15501892446 | 3 |
| 17 | 陈阳 | 2004-09-16 | 1991-04-10 | chenyang@tedu.cn | 15565662056 | 3 |
| 18 | 戴璐 | 2001-11-30 | 1975-05-16 | dailu@tedu.cn | 13465236095 | 3 |
| 19 | 陈斌 | 2019-07-04 | 2000-01-22 | chenbin@tarena.com | 13621656037 | 3 |
+-------------+-----------+------------+------------+--------------------+--------------+---------+
6 rows in set (0.00 sec)
查询2018年比100号员工工资高的工资信息
mysql> select *from salary
-> where year(date)=2018 and month(date)=12 and basic>(select basic from salary where year(date)=2018 and month(date)=12 and employee_id=100);
查询比开发部人数少的部门
1,查询开发部编号
select dept_id from departments where dept_name='开发部';
2,查询开发部人数
select count(*) from employees where dept_id=4;
3,查询各部门人数
select dept_id,count(*) from employees
group by dept_id;
4,查询人数比55 少的部门
select dept_id,count(*) from employees
group by dept_id
having count(*)<55;
select dept_id,count(*) from employees
group by dept_id
having count(*)<(
select count(*) from employees where dept_id=4 (
select dept_id from departments where dept_name='开发部'
)
);
查询每个部门人数
mysql> select d.*,(select count(*) from employees as e where d.dept_id=e.dept_id) as amount from departments as d;
+---------+-----------+--------+
| dept_id | dept_name | amount |
+---------+-----------+--------+
| 1 | 人事部 | 8 |
| 2 | 财务部 | 5 |
| 3 | 运维部 | 6 |
| 4 | 开发部 | 55 |
| 5 | 测试部 | 12 |
| 6 | 市场部 | 9 |
| 7 | 销售部 | 35 |
| 8 | 法务部 | 3 |
| 9 | NULL | 0 |
+---------+-----------+--------+
9 rows in set (0.00 sec)
分页查询LIMIT
mysql> select employee_id,name from employees
-> order by employee_id
-> limit 0,5;
+-------------+-----------+
| employee_id | name |
+-------------+-----------+
| 1 | 梁伟 |
| 2 | 郭岩 |
| 3 | 李玉英 |
| 4 | 张健 |
| 5 | 郑静 |
+-------------+-----------+
5 rows in set (0.00 sec)
mysql> select employee_id,name from employees order by employee_id limit 5,5;
+-------------+-----------+
| employee_id | name |
+-------------+-----------+
| 6 | 牛建军 |
| 7 | 刘斌 |
| 8 | 汪云 |
| 9 | 张建平 |
| 10 | 郭娟 |
+-------------+-----------+
5 rows in set (0.00 sec)
联合查询UNION
mysql> (
-> select name, birth_date from employees
-> where year(birth_date)<1972
-> )
-> union
-> (
-> select name, birth_date from employees
-> where year(birth_date)>2000
-> );
+-----------+------------+
| name | birth_date |
+-----------+------------+
| 梁伟 | 1971-08-19 |
| 张建平 | 1971-11-02 |
| 窦红梅 | 1971-09-09 |
| 温兰英 | 1971-08-14 |
| 朱文 | 1971-08-15 |
| 和林 | 1971-12-10 |
+-----------+------------+
6 rows in set (0.00 sec)
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