記錄一個SQL語句 case select 1
阿新 • • 發佈:2020-11-12
select Code, CodeName, CodeAlias, ComCode, OtherSign from ldcode where codetype = 'edorapptype' and code <> (case when (select 1 from lccont b where b.contno = 'W86190001290019' and b.trdingchannel like 'ZFB%') = 1 then '-9' else '9' end) and othersign = '1' order by length(code), code asc
去掉(case when)
select Code, CodeName, CodeAlias, ComCode, OtherSign from ldcode where codetype = 'edorapptype' and code <> '-9' and othersign = '1'
分析case when 1= 1 then '-9' else '9' end
(case when (select 1 from lccont b where b.contno = 'W86190001290019' and b.trdingchannel like 'ZFB%') = 1 then '-9' else '9' end)
分析 select 1
select 1 from lccont b where b.contno = 'W86190001290019' and b.trdingchannel like 'ZFB%'
select * ,select 某欄位,
可以用來查詢表中是否有符合條件的記錄(比如select 1 from seckill where id = 1001;
),select 1一般用來當作條件使用,比如exists( select 1 from 表名)等。select 1的效率比select 列名
和select*
快,因為不用查字典表。