【群答疑20210525-3】MySQL限制时间是当前月，或者月区间查询

群问题：finebi里写sql  怎么限制时间是当前月  或者几月到几月

 经过确认，是MySQL

先抛出网上例子

 本地环境验证：

1、查询当月数据 （date字段为varchar类型）

 2、月份区间（create_time字段为varchar类型）后面改了字段名

 月份区间，方法2

 查看字段类型，desc 表名；

 

 如果是datetime类型，方法1：月区间直接比较 left截取

 

如果是datetime类型，方法2：月区间间接比较 year 和month函数

 

中间涉及所有练习代码

-- SELECT * from TestUsers1 WHERE name like 'user_8%' ;

-- UPDATE TestUsers1
--   SET date=NOW()
--   WHERE name like 'user_8%';

-- UPDATE TestUsers1
--   SET create_time='2021-04-26 19:00:00'
--   WHERE name = 'user_129Yu6z4';
-- UPDATE TestUsers1
--   SET create_time='2021-01-26 19:00:00'
--   WHERE name = 'user_12vV5aQG';    
-- UPDATE TestUsers1
--   SET create_time='2021-03-26 19:00:00'
--   WHERE name = 'user_12VoT0mp';    
-- UPDATE TestUsers1
--   SET create_time='2021-02-26 19:00:00'
--   WHERE name = 'user_12rFuaD0';    
-- SELECT str_to_date(create_time,'%Y-%m-%d') from TestUsers1 ;    

SELECT * from TestUsers1 
WHERE DATE_FORMAT(create_time, '%Y-%m') BETWEEN '2021-01' and  '2021-04';

SELECT * from TestUsers1 
WHERE DATE_FORMAT(create_time, '%Y-%m') = '2021-02';


SELECT * from TestUsers1 
WHERE left(create_time, 7) BETWEEN '2021-01' and  '2021-04';

desc TestUsers1;

SELECT * from TestUsers1 WHERE name ='user_129Yu6z4';
SELECT * from TestUsers1 WHERE name in ('user_129Yu6z4','user_12vV5aQG','user_12VoT0mp','user_12rFuaD0');

UPDATE TestUsers1
  SET create_time='2021-05-26 19:00:00'
  WHERE name = 'user_12vV5aQG';    

SELECT * from TestUsers1 WHERE name like 'user_12%' ;

-- desc TestUsers1;

-- alter  table TestUsers1 change date create_time varchar(25) ; 

-- CREATE TABLE TestUsers2 LIKE TestUsers1;
-- INSERT INTO TestUsers2 SELECT * FROM TestUsers1;
-- SELECT * FROM TestUsers2;

select DISTINCT CHAR_LENGTH(create_time) from TestUsers1;

-- 修改为datetime
ALTER TABLE TestUsers1 MODIFY create_time datetime;

SELECT * from TestUsers1 
WHERE left(create_time, 7) BETWEEN '2021-01' and  '2021-04';

SELECT * from TestUsers1 
WHERE year(create_time)=2021 and month(create_time) BETWEEN 1 and 4;