如何从 Database.ExecuteSqlCommand 调用的存储过程中获取字符串结果答案

【问题标题】：How can I get a string result from a stored procedure called by Database.ExecuteSqlCommand如何从 Database.ExecuteSqlCommand 调用的存储过程中获取字符串结果
【发布时间】：2017-04-20 20:04:01
【问题描述】：

我在 SQL Server 2016 中有一个存储过程，我想使用 Entity Framework Core v1.1.1 从 ASP.Net Core 项目中的方法调用它。

这是我的方法...

    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;
        }

    }

这是我的存储过程...

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

当我从 SSMS 2016 运行存储过程时，我得到了所需的字符串结果（即 00000123460），但上面列出的 GetNextSerialNumber 方法中的结果值为 -1。

有什么想法吗？

提前感谢您提供的任何帮助。

【问题讨论】：

标签： c# .net-core entity-framework-core sql-server-2016

【解决方案1】：

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

ExecuteSqlCommand 只返回执行结果（它是-1）。要获取序列号，只需检查命令执行后的输出参数值即可：

var val = serialNumber.Value;

【讨论】：

就是这样。奇迹般有效。谢谢:)