-- 查询练习 1------------

CREATE TABLEstu (

sidCHAR(6),

snameVARCHAR(50),

ageINT,

genderVARCHAR(50)

);INSERT INTO stu VALUES('S_1001', 'liuYi', 35, 'male');INSERT INTO stu VALUES('S_1002', 'chenEr', 15, 'female');INSERT INTO stu VALUES('S_1003', 'zhangSan', 95, 'male');INSERT INTO stu VALUES('S_1004', 'liSi', 65, 'female');INSERT INTO stu VALUES('S_1005', 'wangWu', 55, 'male');INSERT INTO stu VALUES('S_1006', 'zhaoLiu', 75, 'female');INSERT INTO stu VALUES('S_1007', 'sunQi', 25, 'male');INSERT INTO stu VALUES('S_1008', 'zhouBa', 45, 'female');INSERT INTO stu VALUES('S_1009', 'wuJiu', 85, 'male');INSERT INTO stu VALUES('S_1010', 'zhengShi', 5, 'female');INSERT INTO stu VALUES('S_1011', 'xxx', NULL, NULL);

----------查询性别为女，并且年龄大于等于50的记录----------

SELECT * FROM stu WHERE gender='female' AND age>=50

----------查询学号为S_1001，或者姓名为liSi的记录----------

SELECT * FROM stu WHERE sid='S_1001' OR sname='liSi'

-- 　查询学号为S_1001，S_1002，S_1003的记录

SELECT * FROM stu WHERE sid='S_1001' OR sid='S_1002' OR sid='S_1003'

-- 　查询学号不是S_1001，S_1002，S_1003的记录

SELECT * FROM stu WHERE NOT (sid='S_1001' OR sid='S_1002' OR sid='S_1003')

-- 　查询年龄为null的记录

SELECT * FROM stu WHERE age IS NULL

-- 　查询年龄在20到40之间的学生记录

SELECT * FROM stu WHERE age BETWEEN 20 AND 40

-- 　查询性别非男的学生记录

SELECT * FROM stu WHERE gend er!='male'

-- 　查询姓名不为null的学生记录

SELECT * FROM stu WHERE NOT sname IS NULL

-- 　查询姓名由5个字母构成的学生记录

SELECT * FROM stu WHERE sname LIKE '_____'

-- 　查询姓名由5个字母构成，并且第5个字母为“i”的学生记录

SELECT * FROM stu WHERE sname LIKE '____i'

-- 　查询姓名以“z”开头的学生记录

SELECT * FROM stu WHERE sname LIKE 'z%'

-- 　查询姓名中第2个字母为“i”的学生记录

SELECT * FROM stu WHERE sname LIKE '_i%'

-- 　查询姓名中包含“a”字母的学生记录

SELECT * FROM stu WHERE sname LIKE '%a%'