如何正確地將DateTime從C＃傳遞到SQL？

Question

我正在嘗試從C＃運行存儲過程，並且在單元測試時遇到轉換錯誤。 我見過的這個問題的每個搜索結果都表明，使用ToString（）不是傳遞DateTime的首選方法。

C＃代碼：

using (SqlConnection lvConn = new SqlConnection(gvSQLConnectionS))
{
    lvConn.Open();
    SqlCommand lvCmd = new SqlCommand(gvSQLsp, lvConn);
    lvCmd.CommandType = CommandType.StoredProcedure;
    lvCmd.Parameters.Add(new SqlParameter(gvSQLparamFunction, gvSQLfunctionUpdLE));
    lvCmd.Parameters.Add(new SqlParameter(gvSQLparamID, lvAAAID));
    lvCmd.Parameters.Add(new SqlParameter(gvSQLparamName, lvName));
    lvCmd.Parameters.Add(new SqlParameter(gvSQLparamPath, lvPath)); 
    SqlParameter lvParameterLE = lvCmd.Parameters.Add(gvSQLparamLE, SqlDbType.DateTime);
    SqlDateTime lvDTnow = new SqlDateTime(DateTime.Now);
    lvParameterLE.Value = lvDTnow;
    lvCmd.ExecuteNonQuery();
}

SQL安裝程序：最后執行（日期時間，空）

存儲過程：

ALTER PROCEDURE [dbo].[sp_BackupCleaner]
    @lvFunction int,
    @lvAAAID varchar(12) = NULL,
    @lvAAAID_new varchar(12) = NULL,
    @lvName varchar(35) = NULL,
    @lvName_new varchar(35) = NULL,
    @lvPath varchar(255) = NULL,
    @lvPath_new varchar(255) = NULL,
    @lvLastExecuted datetime = NULL
AS
BEGIN
    SET NOCOUNT ON;

    DECLARE @lvSQL varchar(max)    

---

IF @lvFunction = 6
    BEGIN
        SET @lvSQL = 'UPDATE [dbo].[Backup_Paths]
                SET [dbo].[Backup_Paths].[Last Executed] = '+@lvLastExecuted+'
                WHERE [dbo].[Backup_Paths].[AAA Client ID] = '''+@lvAAAID+'''
                AND [dbo].[Backup_Paths].[Process Name] = '''+@lvName+'''
                AND [dbo].[Backup_Paths].[UNC Path] = '''+@lvPath+''''
    END

execute(@lvSQL)
END

拋出異常：

System.Data.SqlClient.SqlException: Conversion failed when converting date and/or time from character string.

Answer 1

執行SET [dbo].[Backup_Paths].[Last Executed] = '+@lvLastExecuted+'就像在C＃中使用.ToString()一樣糟糕。

如果您不進一步動態修改@lvSQL ，則可以直接執行查詢

IF @lvFunction = 6
BEGIN
    UPDATE [dbo].[Backup_Paths]
            SET [dbo].[Backup_Paths].[Last Executed] = @lvLastExecuted
            WHERE [dbo].[Backup_Paths].[AAA Client ID] = @lvAAAID 
            AND [dbo].[Backup_Paths].[Process Name] =  @lvName
            AND [dbo].[Backup_Paths].[UNC Path] = @lvPath
END

如果要進一步編輯查詢，則需要使用sp_executesql並將參數轉發到動態查詢。

IF @lvFunction = 6
BEGIN
    SET @lvSQL = 'UPDATE [dbo].[Backup_Paths]
            SET [dbo].[Backup_Paths].[Last Executed] = @lvLastExecuted
            WHERE [dbo].[Backup_Paths].[AAA Client ID] = @lvAAAID
            AND [dbo].[Backup_Paths].[Process Name] = @lvName
            AND [dbo].[Backup_Paths].[UNC Path] = @lvPath'
END

SET @lvSQL = @lvSQL + ' WHERE [dbo].[Backup_Paths].SomeProp = 7'

execute sp_executesql @lvSQL, '@lvFunction int,
                               @lvECMID varchar(12),
                               @lvECMID_new varchar(12),
                               @lvName varchar(35),
                               @lvName_new varchar(35),
                               @lvPath varchar(255),
                               @lvPath_new varchar(255),
                               @lvLastExecuted datetime',
                      @lvFunction,
                      @lvECMID,
                      @lvECMID_new,
                      @lvName,
                      @lvName_new,
                      @lvPath,
                      @lvPath_new,
                      @lvLastExecuted;

Answer 2

無需使用動態SQL。 通常，應避免使用動態SQL。 很難找到不能用更好的東西代替動態SQL的情況。

只需編寫並運行所需的語句即可：

IF @lvFunction = 6
    BEGIN
        UPDATE [dbo].[Backup_Paths]
            SET [dbo].[Backup_Paths].[Last Executed] = @lvLastExecuted
            WHERE [dbo].[Backup_Paths].[AAA Client ID] = @lvAAAID
            AND [dbo].[Backup_Paths].[Process Name] = @lvName
            AND [dbo].[Backup_Paths].[UNC Path] = @lvPath
    END

注意

如果存儲過程執行許多不同的任務，則強烈表明應將其分解為單獨的過程。

Answer 3

問題是嘗試使用+運算符將Datetime變量與字符串文字連接起來。 如果您使用的是SqlServer 2012或更高版本，則可以使用CONCAT ，這樣可以解決此問題。 （但當該值為NULL時，可能會使查詢失敗）

CONCAT('select blah blah blah', @myDateTimeValue);