Question

我是Sql的新手。我有两张桌子

table_A (student_id, last_name, email, schoolA, ...)

table_B (student_id, last_name, email, schoolB, ...)

在table_A中，有些student_id为Null或＆＃39;（空）。

从table_B中选择student_id插入table_A＆＃39; student_id colm

当只匹配last_name和email时，同样当A.student_id为Null或。时   空。

这就是我的想法

INSERT INTO table_A (student_id) 
SELECT student_id 
    From table_B 
    WHERE table_A.last_name = table_B.last_name AND table_A.email = table_B.email 
        AND table_A.student_id ='' OR table_A.student_id = NULL

我知道我写的sql没有任何意义。我只是想得到一个简单的例子或一些想法。

谢谢！

Answer 1

这听起来更像是public async Task <Lead> BuildLeadFromRequest(object request) { var req = request as WebApplicationRequest; if (req == null) throw new Exception(); //TODO: Something better than throwing an exception }语句，而不是UPDATE。

INSERT

请注意，您将student_id与UPDATE A SET A.student_id = B.student_id FROM table_A A INNER JOIN table_B B ON A.last_name = B.last_name AND A.email = B.email WHERE (A.student_id ='' OR A.student_id IS NULL)进行比较，而不是IS NULL。括号也很重要。

Answer 2

无论如何试试这个：

INSERT INTO table_A (STUDENT_ID)
SELECT B.student_id 
    From table_B AS B, TABLE_A AS A
    WHERE (A.last_name = B.last_name AND A.email = B.email )
        OR A.STUDENT_ID ='' OR A.STUDENT_ID IS NULL

SQL选择带条件的插入（在这两个表之间）

2 个答案: