mysql命令行模式（3）

select * from user where name is null;


select * from user where name is not null;


select ISNULL(name) from user; # true 1  /  false 0


select NULLIF(name,'张三') from user;

SELECT
	count(*)
FROM
	USER;


SELECT
	count(
		CASE
		WHEN sex = '女' THEN
			sex
		END
	)
FROM
	USER;