如何從Database.ExecuteSqlCommand調用的存儲過程中獲取字符串結果

Question

我在SQL Server 2016中有一個存儲過程，我想使用Entity Framework Core v1.1.1從ASP.Net Core項目中的方法調用該存儲過程。

這是我的方法

    private string GetNextSerialNumber(string a_mailerId, string a_serviceTypeCode)
    {
        try
        {
            var mailerId = new SqlParameter
            {
                ParameterName = "@mailerId",
                SqlDbType = SqlDbType.NVarChar,
                Direction = ParameterDirection.Input,
                Size = 9,
                Value = a_mailerId
            };

            var serviceTypeCode = new SqlParameter
            {
                ParameterName = "@serviceTypeCode",
                SqlDbType = SqlDbType.NVarChar,
                Direction = ParameterDirection.Input,
                Size = 4,
                Value = a_serviceTypeCode
            };

            var serialNumber = new SqlParameter
            {
                ParameterName = "@serialNumber",
                SqlDbType = SqlDbType.NVarChar,
                Size = 14,
                Direction = ParameterDirection.Output
            };

            var result = m_mailpieceRoContext.Database.ExecuteSqlCommand(
                "exec GetNextSerialNumber @mailerId, @serviceTypeCode, @serialNumber OUT", mailerId, serviceTypeCode, serialNumber);


            return result;

        }
        catch (Exception ex)
        {

            throw;
        }

    }

這是我的存儲過程...

ALTER PROCEDURE [dbo].[GetNextSerialNumber]
    @mailerId               NVARCHAR(9),
    @serviceTypeCode        NVARCHAR(4),
    @serialNumber           NVARCHAR(14)    OUTPUT
AS
BEGIN
    SET NOCOUNT ON;
    DECLARE @counter        BIGINT
    DECLARE @start_counter  BIGINT
    DECLARE @end_counter    BIGINT
    DECLARE @length         INT
    DECLARE @tempCounters   TABLE
    (
        current_counter     BIGINT,
        start_counter       BIGINT,
        end_counter         BIGINT,
        [length]            INT
    )

    INSERT INTO
        @TempCounters
    SELECT 
        current_counter,
        start_counter,
        end_counter,
        [length]
    FROM 
        MailerIdCounters
    WHERE 
        mailer_id = @mailerId
        AND service_type_code = @serviceTypeCode
        AND active = 1


    IF EXISTS (SELECT * FROM @tempCounters)
    BEGIN
        SELECT @counter = current_counter FROM @tempCounters
        SELECT @start_counter = start_counter FROM @tempCounters
        SELECT @end_counter = end_counter FROM @tempCounters
        SELECT @length = [length] FROM @tempCounters
    END

    IF (@counter + 1) > @end_counter
        SET @counter = @start_counter
    ELSE 
        SET @counter = @Counter  + 1

    UPDATE MailerIDCounters
    SET current_counter = @counter
    WHERE mailer_id = @mailerId
    AND service_type_code = @serviceTypeCode

    SELECT RIGHT('00000000000000'+CAST(@counter AS VARCHAR(14)), @length)
    SET @serialNumber = @counter
END   

當我從SSMS 2016運行存儲過程時，我得到了所需的字符串結果（即00000123460），但是上面列出的GetNextSerialNumber方法中的result值為-1。

有任何想法嗎？

在此先感謝您提供的任何幫助。

Answer 1

context.Database.ExecuteSqlCommand(
   "exec GetNextSerialNumber @serialNumber OUT", serialNumber);

ExecuteSqlCommand僅返回執行結果（它為-1）。 要獲取序列號，只需在執行命令后檢查輸出參數值即可：

var val = serialNumber.Value;