Sproc参数仅返回第一个字符

Question

我有一个sproc和一些C#调用它.我的问题是两个(N)VARCHAR值只返回第一个字符.其他一切都很好.为什么只返回第一个字符？

所以

Content = (string)cmd.Parameters["@SmsContent"].Value,
ToNumber = (string) cmd.Parameters["@ToNumber"].Value,

两者都只返回第一个字符.

这是我的特色:

ALTER PROCEDURE [dbo].[GetNextSms]
(   
    @SmsId UNIQUEIDENTIFIER OUTPUT, 
    @SmsContent NVARCHAR OUTPUT, 
    @ToNumber VARCHAR OUTPUT,
    @TimeAccepted DATETIME OUTPUT
)
AS
BEGIN TRANSACTION
    -- 1. Get 1 row
    SET ROWCOUNT 1
        SELECT @SmsId = SmsId FROM SendQueue
        WHERE ProcessingStarted = 0
    SET ROWCOUNT 0
    -- 2. Set as processing
    UPDATE SendQueue 
        SET ProcessingStarted = 1
        WHERE SmsId = @SmsId
    -- 3. Return data
    SELECT @SmsId = SmsId,
        @SmsContent = SmsContent,
        @ToNumber = ToNumber,
        @TimeAccepted = TimeAccepted
    FROM SendQueue
    WHERE SmsId = @SmsId;

COMMIT

这是我的C#

connection.Open();
var cmd = new SqlCommand(@"GetNextSms", connection) {CommandType = CommandType.StoredProcedure};
SqlParameter param = cmd.Parameters.Add("@SmsId", SqlDbType.UniqueIdentifier);
param.Direction = ParameterDirection.Output;
param = cmd.Parameters.Add("@ToNumber", SqlDbType.VarChar,50);
param.Direction = ParameterDirection.Output;
param = cmd.Parameters.Add("@SmsContent", SqlDbType.NVarChar,1024);
param.Direction = ParameterDirection.Output;
param = cmd.Parameters.Add("@TimeAccepted", SqlDbType.DateTime);
param.Direction = ParameterDirection.Output;


if (cmd.ExecuteNonQuery() > 0)
{
    sms = new Sms
              {
                  SmsId = ((Guid) cmd.Parameters["@SmsId"].Value),
                  Content = (string)cmd.Parameters["@SmsContent"].Value,
                  ToNumber = (string) cmd.Parameters["@ToNumber"].Value,
                  TimeAccepted = ((DateTime) cmd.Parameters["@TimeAccepted"].Value)
              };
}

Answer 1

基于一些搜索(即我还没有尝试过),您应该使用长度声明存储过程参数,即

ALTER PROCEDURE [dbo].[GetNextSms]
(   
    @SmsId UNIQUEIDENTIFIER OUTPUT, 
    @SmsContent NVARCHAR(1024) OUTPUT, 
    @ToNumber VARCHAR(50) OUTPUT,
    @TimeAccepted DATETIME OUTPUT
)

如果这不是答案,请道歉,但值得一试.它似乎同意MSDN文档,该文档声明NVARCHAR/VARCHAR的默认长度为1.