Question

sql 有没有带条件插入语句

我想插入一件记录时检查该记录是否存在，但不想先查询一次，有没有带条件的插入语句呀。我写的INSERT INTO mysub (customerId,sub_id) values(1,2) if mysub.sub_id not in (select my.sub_id as sub_id from mysub my where sub) 提示第 1 行: ')' 附近有语法错误。

Answer 1

直接使用WHERE，条件不满足时就不会有记录被插入。
INSERT INTO mysub (customerId,sub_id) values(1,2) WHERE mysub.sub_id not in (select my.sub_id as sub_id from mysub my where sub)

Answer 2

用存在判断符
if not exists(select sub_id from mysub where sub_id=2)
insert into mysub (customerId,sub_id) values(1,2)

Answer 3

栽培者对