调用存储过程中的输出参数必须指定参数方向

存储过程：

ALTER PROCEDURE CreateBoard
    (
        @ClassName    varchar(50),
        @BoardName    varchar(50),
        @ClassID    varchar(50) output
    )
AS
    declare @BoardCount int;
    Set @ClassID = ( Select ClassID from tbClass where ClassName=@ClassName );
    Insert into tbBoard (BoardName, BoardClassID) values (@BoardName, @ClassID);
    Set @BoardCount = ( Select count(*) from tbBoard );
    RETURN @BoardCount;

 

C#代码：

using (SqlConnection conn = new SqlConnection("server=CrystalKing-PC;database=Forum;Trusted_connection=True")) { conn.Open(); using (SqlCommand cmd = new SqlCommand("CreateBoard", conn)) { cmd.CommandType = CommandType.StoredProcedure; cmd.Parameters.Add("@ClassName", SqlDbType.VarChar, 50); cmd.Parameters["@ClassName"].Value = tbClassName.Text; cmd.Parameters.Add("@ClassID", SqlDbType.VarChar, 50); cmd.Parameters["@ClassID"].Direction = ParameterDirection.Output; cmd.Parameters.Add("@BoardName", SqlDbType.VarChar, 50); cmd.Parameters["@BoardName"].Value = tbBoardName.Text; cmd.ExecuteNonQuery(); foreach (SqlParameter p in cmd.Parameters) { Response.Write(string.Format("参数：{0}, 参数值：{1}<br />", p.ParameterName, p.Value)); } } }