从存储过程获取返回值

Question

我试图从C＃中的存储过程获取返回值，但它总是返回{}。我的代码如下：

SqlCommand cmd = new SqlCommand (); 
cmd.CommandText = "EXEC dbo.verifyEmailDomain @Domain, @RESULT"; 
cmd.Connection = con; 

SqlParameter domain_p = new SqlParameter ("@Domain", SqlDbType.NVarChar); 
domain_p.Value = domain; 
cmd.Parameters.Add (domain_p); 

SqlParameter ret = new SqlParameter("@RESULT", SqlDbType.Int); 
ret.Direction = ParameterDirection.Output; 
cmd.Parameters.Add (ret); 

con.Open (); 
cmd.ExecuteNonQuery (); 
var value = cmd.Parameters ["@RESULT"].Value; 
con.Close (); 

我也试图设置 “ret.Direction = ParamaterDirection.ReturnValue” 无济于事

存储过程如下：

ALTER PROCEDURE [dbo].[verifyEmailDomain] 
    -- Add the parameters for the stored procedure here 
    @Domain nvarchar(200), 
    @RESULT INT OUTPUT 
AS 
BEGIN 
    -- SET NOCOUNT ON added to prevent extra result sets from 
    -- interfering with SELECT statements. 
    SET NOCOUNT ON; 

    -- Insert statements for procedure here 
    SELECT @RESULT = COUNT(*) 
    FROM Josh.dbo.refDomains 
    WHERE LOWER(EMAIL_DOMAIN)=LOWER(@Domain) 

    RETURN @RESULT 
END 

Answer 1

如果你可以通过输出参数调用存储过程来告诉它：

cmd.CommandText = "EXEC dbo.verifyEmailDomain @Domain, @RESULT OUTPUT"; 

Yo你可以通过指定过程名称来节省自己的麻烦：

cmd.CommandText = "dbo.verifyEmailDomain"; 
cmd.CommandType = CommandType.StoredProcedure; 

Answer 2

而不是创建另一个名为return的变量，为什么不只是返回select语句？

ALTER PROCEDURE [dbo].[verifyEmailDomain] 
    -- Add the parameters for the stored procedure here 
    @Domain nvarchar(200), 
AS 
BEGIN 

    SET NOCOUNT ON; 


    RETURN(SELECT COUNT(*) 
    FROM Josh.dbo.refDomains 
    WHERE LOWER(EMAIL_DOMAIN)=LOWER(@Domain)) 
END 

然后更改此代码：

SqlCommand cmd = new SqlCommand (); 
cmd.CommandText = "EXEC dbo.verifyEmailDomain @Domain, @RESULT"; 
cmd.Connection = con; 

看起来像这样：

SqlCommand cmd = new SqlCommand (); 
cmd.CommandText = "dbo.verifyEmailDomain"; 
cmd.CommandType = CommandType.StoredProcedure; 
cmd.Connection = con; 

这：

SqlParameter ret = new SqlParameter("@RESULT", SqlDbType.Int); 
ret.Direction = ParameterDirection.Output; 
cmd.Parameters.Add (ret); 

看起来像这样：

SqlParameter ret = new SqlParameter(); 
ret.Direction = ParameterDirection.ReturnValue; 
ret.ParameterName = "@RESULT"; 
cmd.Parameters.Add(ret); 

在这个时候，你的sql返回@Return的值和返回值都是相同的东西。那种毫无意义的想法:)。