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mysql条件查询if case用法
- WBOYOriginal
- 2016-06-07 16:17:551872browse
where条件查询 代码如下 select * from news where DATE(adddate) between '2011-04-20' - INTERVAL 5 DAY and '2011-04-20' + INTERVAL 5 DAY select * from news where DATE(adddate) in ('2011-04-20','2011-04-15','2011-04-25') IF条件语句的使用 mysql
where条件查询
代码如下
select * from news where DATE(adddate) between
'2011-04-20' - INTERVAL 5 DAY and '2011-04-20' + INTERVAL 5 DAY
select * from news where DATE(adddate) in ('2011-04-20','2011-04-15','2011-04-25')
IF条件语句的使用
mysql条件判断语句if的使用:先判断数据库中是否存在是否存在指定值存在就修改不存在就添加。
这里我就用啦mysql存储过程的if语句
代码如下
DROP PROCEDURE IF EXISTS 过程名;
CREATE PROCEDURE 过程名(
IN trueName VARCHAR(100),
IN phone VARCHAR(100),
IN qqmsn VARCHAR(100),
IN mail VARCHAR(100),
IN mac VARCHAR(100),
IN heartip VARCHAR(100)
)
NOT DETERMINISTIC
SQL SECURITY DEFINER
COMMENT ''
BEGIN
SELECT count(id) INTO @maccount from `表名` where `表名`.mac=mac; --是否存在此记录
if (@maccount>0) THEN
update `表名` set `trueName`=trueName,`phone`=phone,`qqmsn`=qqmsn,`mail`=mail,`mac`=mac,
`heart`=`heart`+1,`heartip`=heartip,`heartdatetime`=CURRENT_TIMESTAMP WHERE 表
名.mac=mac;
ELSE
insert into `表名` (`trueName`,`phone`,`qqmsn`,`mail`,`mac`,`heartip`,`heartdatetime`)VALUES(trueName,phone,qqmsn,
mail,mac,heartip,CURRENT_TIMESTAMP);
end IF;
END
case条件语句
代码如下
select substr(t1.area_id, 1, 1) type,
substr(t1.area_id, 2) id,
case substr(t1.area_id, 1, 1)
when 'c' then
(select t2.country
from countnumber.dbtable_countryid t2
where t2.id = substr(t1.area_id, 2))
else
(select distinct t3.province
from countnumber.dbtable_provinceid t3
where t3.id = substr(t1.area_id, 2))
end name
from t_ad_area t1
在第一个方案的返回结果中，， value=compare-value。而第二个方案的返回结果是第一种情况的真实结果。如果没有匹配的结果值，则返回结果为ELSE后的结果，如果没有ELSE 部分，则返回值为 NULL。
代码如下
mysql> SELECT CASE 1 WHEN 1 THEN 'one'
-> WHEN 2 THEN 'two' ELSE 'more' END;
-> 'one'
mysql> SELECT CASE WHEN 1>0 THEN 'true' ELSE 'false' END;
-> 'true'
mysql> SELECT CASE BINARY 'B'
-> WHEN 'a' THEN 1 WHEN 'b' THEN 2 END;
-> NULL