sql - 这个 SQL 我在做什么错？

Question

当我运行它时，它不会引发错误，但它也不会插入/删除条目。我不知道为什么它不起作用。

DECLARE @trAction VARCHAR(5)
  SET @trAction = 'addTR'

  IF EXISTS (SELECT TransgeneID
            FROM tbl_MT
            WHERE MouseID = '3' AND TransgeneID = '3')
    IF (@trAction = 'rmvTR')    
      DELETE
      FROM tbl_MT
      WHERE MouseID = '3' AND TransgeneID = '3'
  ELSE
    IF (@trAction = 'addTR')  
      INSERT INTO tbl_MT 
      VALUES ('3', '3')

Answer 1

首先，将BEGIN和END放在IF's：

  DECLARE @trAction VARCHAR(5)
  SET @trAction = 'addTR'

  IF EXISTS (SELECT TransgeneID
            FROM tbl_MT
            WHERE MouseID = '3' AND TransgeneID = '3')
  BEGIN
    IF (@trAction = 'rmvTR')    
    BEGIN
      DELETE
      FROM tbl_MT
      WHERE MouseID = '3' AND TransgeneID = '3'
    END
  END
  ELSE
  BEGIN
    IF (@trAction = 'addTR')  
    BEGIN
      INSERT INTO tbl_MT 
      VALUES ('3', '3')
    END
  END

第二个也是最后一个，如果第一个IF是真的，内在IF (@trAction = 'rmvTR')就会失败，什么也做不了。