例如存储过名为: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执行动态的SQL语句
注意:动态的sql必须包含于圆括号内如:
- exec (‘select * from mytable’)
使用EXEC执行动态sql语句注意下面问题
1.不能有输入参数,输出参数
下面的脚本是错误的:
- 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.园括号内部能使用函数或case表达式
下面的脚本是错误的:
- 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
不过把函数放在变量中是可以的:
- 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.不能利用重用执行计划,存所以存在性能问题
- 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
当@i = 10248, 10249, 10250要生成3个执行计划。
4。容易被sql注入,存在安全问题。
- 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
实际执行的sql为:
- SELECT * FROM dbo.Employees WHERE LastName = ” DROP TABLE dbo.Employees –‘;