Question

SQL语句中能否含有if....else...判断语句?

有个表, 其中有col1,col2,和col3三列, 如果col1>1, 输出col2, 否则输出col3, 这样的条件能否用SQL语句实现? 尝试了很久, 不得其解, 求高手解答

Answer 1

select case when col1>1 then col2 else col3 end from 表

Answer 2

下面是 If 的用法

select b2.*,IF(b2.cday-DATEDIFF(NOW(),cdate)>=0,b2.cday-DATEDIFF(NOW(),cdate),0) cdate1
from buscard b2 WHERE CARD LIKE '%%'   and
IF(b2.cday-DATEDIFF(NOW(),cdate)>=0,b2.cday-DATEDIFF(NOW(),cdate),0) =5

Answer 3

if (1=2)
begin
select 'a'
end
else
begin
select 'b'
select 'c'
end

Answer 4

SELECT
IF (col1 > 1, col2, col3)
FROM
TABLE;