Sql server TSQL-对于每个like语句

我想为每一个类似SQL的语句编写一个SQL语句，但我无法理解它

如果我的表A如下所示：

[dbo].[TABLE_A](
    [EmpID] [INT],
    [FName] [varchar](50) NULL,
    [LName] [varchar](50) NULL
)

[dbo].[TABLE_B](
    [EmployeeActivity] [varchar](50) NULL,
    [EmpID] [INT]
)

FOR EACH DISTINCT [EmployeeActivity] RETURN 
  [TABLE_B].[EmployeeActivity],
  [TABLE_A].[FName], 
  [TABLE_A].[LName], 
  [TABLE_A].[EmpID],
  CASE
    WHEN ([TABLE_B].[EmployeeActivity] IS NULL) THEN ('NO')
  ELSE 'YES'
  END

…我的表B如下所示：

[dbo].[TABLE_A](
    [EmpID] [INT],
    [FName] [varchar](50) NULL,
    [LName] [varchar](50) NULL
)

[dbo].[TABLE_B](
    [EmployeeActivity] [varchar](50) NULL,
    [EmpID] [INT]
)

FOR EACH DISTINCT [EmployeeActivity] RETURN 
  [TABLE_B].[EmployeeActivity],
  [TABLE_A].[FName], 
  [TABLE_A].[LName], 
  [TABLE_A].[EmpID],
  CASE
    WHEN ([TABLE_B].[EmployeeActivity] IS NULL) THEN ('NO')
  ELSE 'YES'
  END

有人能帮我写一个查询来做这样的事情吗：

[dbo].[TABLE_A](
    [EmpID] [INT],
    [FName] [varchar](50) NULL,
    [LName] [varchar](50) NULL
)

[dbo].[TABLE_B](
    [EmployeeActivity] [varchar](50) NULL,
    [EmpID] [INT]
)

FOR EACH DISTINCT [EmployeeActivity] RETURN 
  [TABLE_B].[EmployeeActivity],
  [TABLE_A].[FName], 
  [TABLE_A].[LName], 
  [TABLE_A].[EmpID],
  CASE
    WHEN ([TABLE_B].[EmployeeActivity] IS NULL) THEN ('NO')
  ELSE 'YES'
  END

结果应该如下所示：

FireDrill12, Bill, Jones, 342,YES
FireDrill13, Bill, Jones, 342,NO
FireDrill14, Bill, Jones, 342,YES
FireDrill12, Smith, Sue, 253,NO
FireDrill13, Smith, Sue, 253,NO
FireDrill14, Smith, Sue, 253,YES

我无法理解这件事

谢谢你的帮助

---

-Allen

SQL无论如何都是一种基于集合的语言，因此它已经在执行“for each”，因此理论上，您可以执行交叉连接以获得每个组合，并使用相关查询进行检查，因此可能类似于：

SELECT DISTINCT
            b.EmployeeActivity,
            a.FName,
            a.LName,
            a.EmpId,
            CASE 
                WHEN EXISTS (SELECT 1 FROM [TABLE_B] c WHERE c.[EmployeeActivity] = b.EmployeeActivity AND c.EmpId = a.EmpId) THEN 'YES' 
                ELSE 'NO' 
            END

FROM        Table_b AS b

CROSS JOIN  Table_a AS a
    ON      a.EmpId = b.EmpId

---

另一个版本使用

internal

join，但更正确的版本使用

left

join，如@Blam所示

SELECT 
    A.*, 
    CASE
        WHEN B.EmployeeActivity IS NULL THEN 'No'
        ELSE 'Yes'
    END
FROM
[dbo].[TABLE_A] A
INNER JOIN [dbo].[TABLE_B] B ON (A.EmpID = B.EmpID)
UNION
SELECT 
    A.*, 
    'No'
FROM
[dbo].[TABLE_A] A
WHERE 
A.EmpID NOT IN (SELECT B.EmpID FROM [dbo].[TABLE_B] B)

---

你的每个。。。语句不是您想要的内容的正确说明。结果示例表看起来需要一个简单的连接！？而且示例数据没有意义。第一列中的EmployeeActivity从不为null，因此在最后一列中不会看到NO。要展开上一条注释，需要一条带有内部联接的SELECT语句。