Question

我有一个表格，我希望根据另一个带有where子句的表添加列IS_TRUE。

即：我有一个名为Employee的表，我有另一个名为Manager的表，现在我想根据以下内容在表IS_True中插入/添加Employee列：

 A.ID = B.ID where ((A.Name Is Not Null) and (B.ID is null))

寻找单个视图来执行此操作而不复制表Employee中的数据。

表Employee

ID|Name|Salary
 1|B   |333
 3|B   |333
 4|B   |333
 1|B   |333

表Manager

ID  |Name
 1  |A
 3  |B
 4  |B
Null|A

结果：

ID|Name|Salary|IS_True
 1|B   |333   |YES
 3|B   |333   |NO
 4|B   |333   |NO
 1|B   |333   |YES

非常感谢您的帮助

Answer 1

SELECT    a.*, 
          CASE WHEN a.name IS NOT NULL AND b.id IS NULL 
               THEN 'YES' 
               ELSE 'NO' 
          END AS is_true
FROM      employee a
LEFT JOIN (SELECT DISTINCT id FROM manager) b ON a.id = b.id

Answer 2

试试这个：在join

中添加一个where子句

SELECT    a.*, 
          CASE WHEN a.name IS NOT NULL AND b.id IS NULL 
               THEN 'YES' 
               ELSE 'NO' 
          END AS is_true
FROM      employee a
LEFT JOIN (SELECT DISTINCT id FROM manager) b ON a.id = b.id
where b.name is null

SQL在视图中使用“左连接”添加列

2 个答案: