将字符串从 MSSQL 转换为 MySQL

Question

我有一个从 SQL DB 读取并写入 MySQL 的应用程序。此应用程序用于为客户端迁移数据。在测试时，我遇到了一条记录的问题，我很困惑。我已经测试了该站点关于使用 C#Encoding 类的各种建议，并且每次都尝试转换它，但在这条记录上没有成功。

SQL 排序规则是SQL_Latin1_General_CP1_CI_AS，MySQL 排序规则是latin1_general_ci 代码示例（在foreach 循环中）如下：

foreach(var pgObj in PgObjList)
{
    //byte[] bytes = Encoding.Default.GetBytes(pgObj.Description);
    //pgObj.Description = Encoding.ASCII.GetString(bytes);

    byte[] utf8Bytes = Encoding.UTF8.GetBytes(pgObj.Description);
    byte[] isoBytes = Encoding.Convert(Encoding.ASCII, Encoding.UTF8, utf8Bytes);
    string uf8converted = Encoding.UTF8.GetString(isoBytes);

    string insertSQL = @"INSERT INTO `mainsite`.`sf_root_items` 
                        (`ID`, 
                        `LoweredName`, 
                        `MenuName`, 
                        `Title`, 
                        `Description`, 
                        `PageType`, 
                        `ExternalUrl`
                        )
                        VALUES
                        ('" + pgObj.ID + @"', 
                        '" + pgObj.LoweredName + @"', 
                        '" + pgObj.MenuName + @"', 
                        '" + pgObj.Title + @"', 
                        '" + pgObj.Description + @"', 
                        '" + pgObj.PageType + @"', 
                        '" + pgObj.ExternalUrl + @"'
                        );";
    string outputMsg;
    // more code here to execute the MySQL statement
}

我得到的最好结果是转换为 ASCII（注释代码）并将文本存储为看起来像汉字的形式。没有例外，但是当我以任何其他方式运行它时，我得到了这条记录的异常。

例外：

MySQL Exception on record#28/r/n
MySql.Data.MySqlClient.MySqlException (0x80004005): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'il vous plaît (RSVP)', 
                                                '0', 
             ' at line 15
       at MySql.Data.MySqlClient.MySqlStream.ReadPacket()
       at MySql.Data.MySqlClient.NativeDriver.GetResult(Int32& affectedRow, Int64& insertedId)
       at MySql.Data.MySqlClient.Driver.GetResult(Int32 statementId, Int32& affectedRows, Int64& insertedId)
       at MySql.Data.MySqlClient.Driver.NextResult(Int32 statementId, Boolean force)
       at MySql.Data.MySqlClient.MySqlDataReader.NextResult()
       at MySql.Data.MySqlClient.MySqlCommand.ExecuteReader(CommandBehavior behavior)
       at MySql.Data.MySqlClient.MySqlCommand.ExecuteNonQuery()
       at SharepointImportDL.SharepointContentImport.GetSitefinityContent.addRootItems(List`1 PgObjList, String WPConnectionString) in C:\Users\Administrator\Source\Repos\TestBinaryWriter\Test Binary Writer\SharepointImportDL\SharepointContentImport\GetSitefinityContent.cs:line 986

第 986 行是 SQL 执行：int output = cmd.ExecuteNonQuery();

还可能值得注意的是，我插入的字符串来自 nvarchar 列 (MSSQL) 和 varchar (MySQL) 列

具有讽刺意味的是，字符串是一个简单的“Répondez s'il vous plaît (RSVP)”（我想揍不得不使用法语文本的自命不凡的人）所以我不太可能'会再次遇到它，但显然我需要处理这种可能性。

Answer 1

在构建 SQL (string insertSQL) 之前转义字符串（例如，pgObj.Description）。否则你会从

之类的东西中得到语法错误

, 'Répondez s'il vous plaît (RSVP)', 

注意单引号中的单引号是怎么回事？还要注意错误是如何指出问题的：

... syntax to use near 'il vous plaît (RSVP)', 

Answer 2

感谢 Palle Due 提出的参数化查询建议，我决定在 MySQL 中编写一个存储过程来处理这些问题。

我的 C# 代码，基于我原来的问题如下：

foreach(var pgObj in PgObjList)
{
    string SP = "sp_insert_root_items";
    string outputMsg = "";

    MySqlConnection myConnection = new MySqlConnection(WPConnectionString);
    MySqlCommand cmd;
    try
    {
        if (myConnection.State != ConnectionState.Open)
        {
            myConnection.Close();
            myConnection.Open();
        }
        cmd = myConnection.CreateCommand();
        cmd.CommandText = SP;
        cmd.CommandType = CommandType.StoredProcedure;

        cmd.Parameters.AddWithValue("@ID", pgObj.ID);
        cmd.Parameters["@ID"].Direction = ParameterDirection.Input;

        cmd.Parameters.AddWithValue("@LoweredName", pgObj.LoweredName);
        cmd.Parameters["@LoweredName"].Direction = ParameterDirection.Input;

        cmd.Parameters.AddWithValue("@MenuName", pgObj.MenuName);
        cmd.Parameters["@MenuName"].Direction = ParameterDirection.Input;

        cmd.Parameters.AddWithValue("@Title", pgObj.Title);
        cmd.Parameters["@Title"].Direction = ParameterDirection.Input;

        cmd.Parameters.AddWithValue("@Description", pgObj.Description);
        cmd.Parameters["@Description"].Direction = ParameterDirection.Input;

        cmd.Parameters.AddWithValue("@PageType", pgObj.PageType);
        cmd.Parameters["@PageType"].Direction = ParameterDirection.Input;

        cmd.Parameters.AddWithValue("@ExternalUrl", pgObj.ExternalUrl);
        cmd.Parameters["@ExternalUrl"].Direction = ParameterDirection.Input;

        cmd.Parameters.AddWithValue("@ParentID", "");
        cmd.Parameters["@ParentID"].Direction = ParameterDirection.Input;

        int output = cmd.ExecuteNonQuery();

        // a value greater than 0 means execution was successful
        if (output > 0)
        {
            counter++;
            //outputMsg = "Record #" + counter.ToString() + " created";

        }
        else
        {
            counter++;
            outputMsg = "There was an error inserting record #" + counter.ToString();
        }

        myConnection.Close();
    }
    catch (Exception ex)
    {
        outputMsg = "MySQL Exception on record#" + counter.ToString() + "/r/n" + ex.ToString();
    }

    returnMsg += outputMsg;

}

下面是一个存储过程的示例 - 它是从 SQLYog 导出的。

DELIMITER $$

/*!50003 CREATE DEFINER=`root`@`localhost` PROCEDURE `sp_insert_root_items`(
        IN ID VARCHAR(255), 
        IN LoweredName VARCHAR(255), 
        IN MenuName VARCHAR(255), 
        IN Title VARCHAR(255), 
        IN Description VARCHAR(500), 
        IN PageType VARCHAR(255), 
        IN ExternalUrl VARCHAR(255), 
        IN ParentID VARCHAR(255)
    )
BEGIN
    INSERT INTO `wp_sf_page_items`
        (`ID`, 
        `LoweredName`, 
        `MenuName`, 
        `Title`, 
        `Description`, 
        `PageType`, 
        `ExternalUrl`, 
        `ParentID`
    )
    VALUES(ID, LoweredName, MenuName, Title, Description, PageType, ExternalUrl, ParentID);  
END */$$
DELIMITER ;