Linq to sql-存储过程

Posted 2020-08-07 dekevin技术博客

带参数的存储过程

创建如下存储过程：

create proc [dbo].[sp_withparameter]
@customerid nchar(5),
@rowcount int output
as
set nocount on
set @rowcount = (select count(*) from customers where customerid = @customerid)

使用同样的方法生成存储过程方法，然后使用下面的代码进行测试：

int? rowcount = -1;
        ctx.sp_withparameter("", ref rowcount);
        Response.Write(rowcount);
        ctx.sp_withparameter("ALFKI", ref rowcount);
        Response.Write(rowcount);

结果输出了“01”。说明ID为“”的顾客数为0，而ID为“ALFKI”的顾客数为1。存储过程的输出参数被封装成了ref参数，对于C#语法来说非常合情合理。SQL代码如下：

EXEC @RETURN_VALUE = [dbo].[sp_withparameter] @customerid = @p0, @rowcount = @p1 OUTPUT
-- @p0: Input StringFixedLength (Size = 5; Prec = 0; Scale = 0) []
-- @p1: InputOutput Int32 (Size = 0; Prec = 0; Scale = 0) [-1]
-- @RETURN_VALUE: Output Int32 (Size = 0; Prec = 0; Scale = 0) []

带返回值的存储过程

再来创建第三个存储过程：

create proc [dbo].[sp_withreturnvalue]
@customerid nchar(5)
as
set nocount on
if exists (select 1 from customers where customerid = @customerid)
return 101
else
return 100

生成方法后，可以通过下面的代码进行测试：

Response.Write(ctx.sp_withreturnvalue(""));
Response.Write(ctx.sp_withreturnvalue("ALFKI"));

运行后程序输出“100101”

多结果集的存储过程

再来创建一个多结果集的存储过程：

create proc [dbo].[sp_multiresultset]
as
set nocount on
select * from customers
select * from employees

[Function(Name="dbo.sp_multiresultset")]
    public ISingleResult<sp_multiresultsetResult> sp_multiresultset()
    {
        IExecuteResult result = this.ExecuteMethodCall(this, ((MethodInfo)(MethodInfo.GetCurrentMethod())));
        return ((ISingleResult<sp_multiresultsetResult>)(result.ReturnValue));
    }

由于现在的VS2008会把多结果集存储过程识别为单结果集存储过程（只认识第一个结果集），我们只能对存储过程方法多小动手术，修改为：

[Function(Name="dbo.sp_multiresultset")]

    [ResultType(typeof(Customer))]

    [ResultType(typeof(Employee))]

    public IMultipleResults sp_multiresultset()

    {

        IExecuteResult result = this.ExecuteMethodCall(this, ((MethodInfo)(MethodInfo.GetCurrentMethod())));

        return (IMultipleResults)(result.ReturnValue);

    }

然后使用下面的代码测试：

var 多结果集存储过程 = ctx.sp_multiresultset();

 var Customers = 多结果集存储过程.GetResult<Customer>();

 var Employees = 多结果集存储过程.GetResult<Employee>();

 GridView1.DataSource = from emp in Employees where emp.FirstName.Contains("A") select emp;

 GridView1.DataBind();

 GridView2.DataSource = from c in Customers where c.CustomerID.StartsWith("A") select c;

 GridView2.DataBind();

使用存储过程新增数据