怎么写动态sql哪里条件？ [英] how to write dynamic sql where condition ?

问题描述

大家好，

i有一个非常奇怪的情况，我需要在sql查询的where子句中写一个动态条件。



我的问题是什么？

i有三张桌子...



1）表A - > EmpID int

2）表B - > EmpID int

2）表C - > EmpID int



现在我想要的是检查



这样的东西..

HI all ,
i have a very weird situation where i need to write a dynamic condition in the where clause in sql query.

what is my issue is
i have three tables...

1) table A - > EmpID int
2) table B - > EmpID int
2) table C - > EmpID int

NOW what i want is to check

something like this ..

SELECT * ....
FroM A,b,c 
WHERE a.empid = b.empid and a.empid = c.empid ....

现在如果这个条件不成立我需要申请

now if this condition is not true i need to apply

a.empid = b.empid OR  a.empid = c.empid

两者同时不会工作。

both simultenously will not work.

推荐答案

请阅读我对这个问题的评论。



我建议从这里开始： SQL联接的可视化表示 [ ^ ]了解 join s而不是 where 子句。



如果你想比较empid的，哪些是哪个是不在表2和表3中，使用 IN [ ^ ]或 EXISTS [ ^ ]条款。

Please, read my comment to the question.

I would suggest to start here: Visual Representation of SQL Joins[^] to learn about joins instead where clause.

If you want to compare empid's, which are and which are not in table2 and table3, use IN[^] or EXISTS[^] clause.

SELECT empid
FROM Table1
WHERE NOT IN (SELECT empid FROM Table2)

尝试加入查询

try a join query

SELECT * From A as a
inner join b as on a.empid = b.empid
inner join c as c on a.empid = c.empid

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