Question

我试图从C＃中的存储过程中获取返回值，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

如果使用输出参数调用存储过程，则需要告诉它：

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

只需指定程序名称即可省去麻烦：

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

Answer 2

不是创建另一个名为return的变量，为什么不直接返回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;

而且：

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);

此时，你的sql返回@Return的值和返回值，它们都是同一个东西。我觉得有点无意义:)。

从存储过程中获取返回值

2 个答案: