如何检查表变量是否有id

Question

我有下表变量

DECLARE @insertedTable Table (ServiceId INT)

我从一些 SQL 查询中插入 ServiceId，

现在我需要使用交叉连接 @insertedTable 将值插入到 BranchServices 表中

我写了以下 SQL 查询

INSERT INTO BranchServices
    SELECT b.BranchId
    ,its.ServiceId
    ,CASE WHEN(SELECT MIN(SortValue) FROM BranchServices WHERE FkBranchId = b.BranchId) IS NOT NULL THEN 0 END
     FROM @insertedTable its
    CROSS JOIN Branch b where b.IsActive = 1;

当@insertedTable 表不存在ServiceId 与BranchServices 表相同时，上述查询工作正常。因为BranchServices的表ServiceId是主键。

所以现在我需要检查，如果BranchServices 表已经有ServiceId 我不需要运行以下查询，否则我需要运行查询。如何使用合并来做到这一点？是的话怎么写

INSERT INTO BranchServices
    SELECT b.BranchId
    ,its.ServiceId
    ,CASE WHEN(SELECT MIN(SortValue) FROM BranchServices WHERE FkBranchId = b.BranchId) IS NOT NULL THEN 0 END
     FROM @insertedTable its
    CROSS JOIN Branch b where b.IsActive = 1;

Answer 1

完全猜测：

INSERT INTO BranchServices (BranchId, ServiceId, OtherColumn) --Don't know what the name of the third column is
SELECT b.BranchId,
       its.ServiceId,
       CASE WHEN (SELECT MIN(SortValue)FROM BranchServices WHERE FkBranchId = b.BranchId) IS NOT NULL THEN 0 END
FROM @insertedTable its
     CROSS JOIN Branch b
     LEFT JOIN BranchServices BS ON its.ServiceId = BS.ServiceId
WHERE b.IsActive = 1
  AND BS.ServiceId IS NULL;

旁注，空白对于编写可读代码非常重要，我建议善用使用它。