sql - SQL语法错误以外部方式创建过程

Question

问题:如果将创建过程中不存在的IF添加为外部名称语句，则会收到语法错误...为什么？
如果我分别运行它们，这两个语句都可以正常工作...

IF  NOT EXISTS 
(
    SELECT * FROM sys.objects 
    WHERE object_id = OBJECT_ID(N'PriceSum') 
    AND type in (N'P', N'PC')
)
CREATE PROCEDURE PriceSum(@sum int OUTPUT)
     AS EXTERNAL NAME MyFirstUdp.[SQL_CLRdll.MySQLclass].PriceSum

Answer 1

因为CREATE PROCEDURE必须是批处理中的第一条语句。

首先删除proc或使用动态SQL

IF  NOT EXISTS 
(
    SELECT * FROM sys.objects 
    WHERE object_id = OBJECT_ID(N'PriceSum') 
    AND type in (N'P', N'PC')
)
exec('CREATE PROCEDURE PriceSum(@sum int OUTPUT)
     AS EXTERNAL NAME MyFirstUdp.[SQL_CLRdll.MySQLclass].PriceSum')

您也可以颠倒逻辑

    IF  EXISTS 
    (
        SELECT * FROM sys.objects 
        WHERE object_id = OBJECT_ID(N'PriceSum') 
        AND type in (N'P', N'PC')
    )

    DROP PROCEDURE PriceSum
    GO --this ends the batch, so the create statement below is fine

    CREATE PROCEDURE PriceSum(@sum int OUTPUT)
AS EXTERNAL NAME MyFirstUdp.[SQL_CLRdll.MySQLclass].PriceSum
  GO