MySQL条件查询语句常用操作全面汇总

-- 查询性别为男的信息
SELECT * FROM t_user WHERE sex='男'
-- 查询性别不为男的信息
SELECT * FROM t_user WHERE NOT sex='男'
-- 查询性别为男并且年龄为20的信息
SELECT * FROM t_user WHERE sex='男' AND age=20
-- 查询性别为男或者年龄为20的信息
SELECT * FROM t_user WHERE sex='男' OR age=20

-- _下划线一次匹配一个字符
-- %一次可以匹配0个或者多个字符
SELECT * FROM t_user WHERE NAME LIKE '_李_'
SELECT * FROM t_user WHERE NAME LIKE 'b__'
SELECT * FROM t_user WHERE NAME LIKE 'b%'

-- 查询体重在100和130之间的信息,包括100和130
SELECT * FROM t_user WHERE weight BETWEEN 100 AND 130
-- 查询体重是100或者110的信息
SELECT * FROM t_user WHERE weight IN(100,110)
-- 查询生日为null或者不为null的信息
SELECT * FROM t_user WHERE birthday IS NULL
SELECT * FROM t_user WHERE birthday IS NOT NULL

SELECT * FROM t_user WHERE age=20 
UNION 
SELECT * FROM t_user WHERE sex='男'

SELECT * FROM t_user WHERE age=20 
UNION ALL
SELECT * FROM t_user WHERE sex='男'

-- 按体重升序排列
SELECT * FROM t_user ORDER BY weight ASC
-- 按体重降序排列
SELECT * FROM t_user ORDER BY weight DESC
-- 如果体重相等,就按照学号来排,升序
SELECT * FROM t_user ORDER BY weight ASC, number ASC

-- 从第一条数据开始查询2条数据(不包括第一条数据)
SELECT * FROM t_user LIMIT 1,2

-- 通过sex分组
-- 这里select后跟的必须是group by后的字段或者分组函数
SELECT sex,AVG(weight) FROM t_user GROUP BY sex
SELECT sex,AVG(weight) FROM t_user GROUP BY sex HAVING sex='女'

SELECT sex,AVG (weight) w
FROM
  t_user
WHERE sex = '男'
GROUP BY sex
HAVING sex = '男'
ORDER BY w ASC
LIMIT 0, 1