Question

我有一个这样的存储过程：

SET NOCOUNT ON;

BEGIN TRAN;
    INSERT INTO [TaskNotification] (TaskId, EmpKey)
        SELECT 
            TaskId, E.EmpKey
        FROM 
            @TaskNotificationTableType TNT
        INNER JOIN 
            Employee E ON E.EmpGuid = TNT.EmpGuid;
COMMIT TRAN

我想知道如何在插入值之前检查列E.EmpKey的值是否存在

IF (E.EmpKey EXISTS) 
    // DO NOTHING
ELSE
    INSERT INTO [TaskNotification] (TaskId, EmpKey)
        SELECT 
            TaskId, E.EmpKey
        FROM 
            @TaskNotificationTableType TNT
        INNER JOIN 
            Employee E ON E.EmpGuid = TNT.EmpGuid;

如何实现？问候

Answer 1

如果您的意思是EmpKey不必在Employee上为NULL，那么对WHERE进行过滤就足够了。

INSERT INTO [TaskNotification] (TaskId, EmpKey)
SELECT 
    TaskId, E.EmpKey
FROM 
    @TaskNotificationTableType TNT
INNER JOIN 
    Employee E ON E.EmpGuid = TNT.EmpGuid
WHERE
    E.EmpKey IS NOT NULL;

如果您不想在TaskNotification中插入一条记录（如果已有的话），请使用WHERE NOT EXISTS。

INSERT INTO [TaskNotification] (TaskId, EmpKey)
SELECT 
    TaskId, E.EmpKey
FROM 
    @TaskNotificationTableType TNT
INNER JOIN 
    Employee E ON E.EmpGuid = TNT.EmpGuid
WHERE
    NOT EXISTS (SELECT 'not in TaskNotification yet' FROM [TaskNotification] T
                WHERE T.EmpKey = E.EmpKey)

Answer 2

@@rowcount返回受最后一条语句影响的行数。

SET NOCOUNT ON;

BEGIN TRAN;
SELECT E.EmpKey
FROM @TaskNotificationTableType TNT;

IF @@rowcount > 0 
  INSERT INTO [TaskNotification] (TaskId, EmpKey)
        SELECT 
            TaskId, E.EmpKey
        FROM 
            @TaskNotificationTableType TNT
        INNER JOIN 
            Employee E ON E.EmpGuid = TNT.EmpGuid;
commit tran

在插入列之前检查列是否包含值T-SQL

2 个答案: