sql - 我的表中的 NULL 值

Question

我正在尝试做一个动态的简单INSERT

SELECT 'INSERT INTO Agency (Agency_Id) VALUES (' + CAST(Agency_Id AS VARCHAR(10)) + ')'   
FROM User 
WHERE User_Id = 1

但是如果我的Agency_IdIS NULL 那么这个查询将只出现NULL在结果中，而不是像INSERT INTO Agency (Agency_Id) VALUES (NULL).

我怎样才能做到这一点 ？

Answer 1

SELECT 'INSERT INTO Agency (Agency_Id) VALUES (' + ISNULL(CAST(Agency_Id AS VARCHAR(10)), 'NULL') + ')'   
FROM User 
WHERE User_Id = 1

Answer 2

只需'NULL'用于空值：

SELECT 'INSERT INTO Agency (Agency_Id) VALUES (' 
        + ISNULL(Agency_Id,'NULL')
        + ')'   
FROM User 
WHERE User_Id = 1