Question

我有一个表变量，其中填充了许多行。我想要实现的是循环遍历表变量的每一行，看看ID列是否存在于另一个标准表中，并将该行添加到新创建的表变量中。

我的代码如下：

DECLARE
@Intervention_ID int

SET @Intervention_ID = 969

/*---Check if intervention has pre-requisites---*/
DECLARE @PreRequisites TABLE
(
    [Intervention_ID] int
)
INSERT INTO @PreRequisites
(
    [Intervention_ID]
)
SELECT IP.[Requisite_ID]
FROM DI_Intervention_Prerequisites IP
WHERE
    IP.[Intervention_ID] = @Intervention_ID
AND IP.[Prerequisite] = 1

/*---Check if pre-requisites have been completed---*/
DECLARE @Result TABLE
(
    [Type_ID] int
  , [Type_Name] nvarchar(max)
  , [Intervention_ID] int
  , [Intervention_Name] nvarchar(max)
)
WHILE NOT EXISTS
(
    SELECT TOP 1 1
    FROM DI_Employee_Intervention EI
    WHERE
        EI.[Intervention_ID] = (SELECT [Intervention_ID] FROM @PreRequisites)
)
    INSERT INTO @Result
    (
        [Type_ID]
      , [Type_Name]
      , [Intervention_ID]
      , [Intervention_Name]
    )

正如您所看到的，我被困在代码的WHILE NOT EXISTS部分。需要发生的是@PreRequisites中DI_Employee_Intervention中不存在@PreRequisites中不存在的每一行，需要将@Result行插入{{1}}。

Answer 1

为什么不使用基于集合的方法而不是现在使用的RBAR（逐行排列）程序方法？

类似的东西：

INSERT INTO @Result([Type_ID], [Type_Name], [Intervention_ID], [Intervention_Name])
  SELECT 
      ... (some columns to match the columns of @Result)......
  FROM 
     dbo.DI_Intervention_Prerequisites IP
  WHERE
     IP.[Intervention_ID] = @Intervention_ID
     AND IP.[Prerequisite] = 1
     AND NOT EXISTS (SELECT * 
                     FROM DI_Employee_Intervention EI
                     WHERE EI.[Intervention_ID] = IP.[Intervention_ID] )

或类似的东西（我没有完全理解你的所有中间步骤以及你为什么采取它们......）

循环遍历表变量并将缺少的行插入新表变量中

1 个答案: