普通SQL語句可以用Exec執行

例如存儲過名為：myprocedure

use AdventureWorks

create procedure myprocedure @city varchar(20)

as

begin

    select * from Person.Address

end

exec myprocedure @city = 'Bothell'

--或

exec myprocedure 'Bothell'

二、使用EXEC執行動態的SQL語句

注意：動態的sql必須包含於圓括號內如：

exec ('select * from mytable')

使用EXEC執行動態sql語句注意下面問題

1.不能有輸入參數，輸出參數

下面的腳本是錯誤的：

DECLARE @i AS INT;
SET @i = 10248;

DECLARE @sql AS VARCHAR(52);
SET @sql = 'SELECT * FROM dbo.Orders WHERE OrderID = @i;';
EXEC(@sql);
GO

2.園括號內部能使用函數或case表達式

下面的腳本是錯誤的：

DECLARE @schemaname AS NVARCHAR(128), @tablename AS NVARCHAR(128);
SET @schemaname = N'dbo';
SET @tablename = N'Order Details';
EXEC(N'SELECT COUNT(*) FROM '
     + QUOTENAME(@schemaname) + N'.' + QUOTENAME(@tablename) + N';');
GO

不過把函數放在變量中是可以的：

DECLARE
  @schemaname AS NVARCHAR(128),
  @tablename AS NVARCHAR(128),
  @sql AS NVARCHAR(539);
SET @schemaname = N'dbo';
SET @tablename = N'Order Details';
SET @sql = N'SELECT COUNT(*) FROM '
  + QUOTENAME(@schemaname) + N'.' + QUOTENAME(@tablename) + N';'
EXEC(@sql);

3.不能利用重用執行計划，存所以存在性能問題

DECLARE @i AS INT;
SET @i = 10248;

DECLARE @sql AS VARCHAR(52);
SET @sql = 'SELECT * FROM dbo.Orders WHERE OrderID = '
  + CAST(@i AS VARCHAR(10)) + N';';
EXEC(@sql);
GO

當@i = 10248, 10249, 10250要生成3個執行計划。

4。容易被sql注入，存在安全問題。

DECLARE @lastname AS NVARCHAR(40), @sql AS NVARCHAR(200);
SET @lastname = N''' DROP TABLE dbo.Employees --';
SET @sql = N'SELECT * FROM dbo.Employees WHERE LastName = '''
  + @lastname + ''';';
EXEC @sql;
GO

實際執行的sql為：

SELECT * FROM dbo.Employees WHERE LastName = '' DROP TABLE dbo.Employees --';