如何设置两个连接字符串 MySqlCommand 对象参数？

Posted 2023-04-12

【中文标题】如何设置两个连接字符串 MySqlCommand 对象参数？

【英文标题】：how to set two connection string MySqlCommand object argument?

【发布时间】：2020-05-14 19:20:36

【问题描述】：

我想创建基于迁移的 Visual Basic 应用程序，用于将 mysql 数据库表迁移到 MS SQL Server 2014，以便通过一键单击事件轻松完成，它将开始迁移您要迁移的任何数据库的数据

这是我编写的主要代码，但是当我想在 MySqlCommand 参数中连接两个连接时，这怎么可能

 private void Start_Click(object sender, EventArgs e)
        
            //MS SQL Connection server
            string connectionString;
            SqlConnection MSSQL;

            connectionString = @"Data Source=DESKTOP-IF12M9R;Initial Catalog=utility;User ID=sa;Password=mysql";
            MSSQL = new SqlConnection(connectionString);

            MSSQL.Open();
            MessageBox.Show("Connection Open of MS SQL !");

            //MySQL server Connectivity
            string connStr = "server=localhost;user=root;database=utility;port=3306;password=''";
            MySqlConnection conn = new MySqlConnection(connStr);
            try
            
                MessageBox.Show("Connecting to MySQL...");

                conn.Open();
                MessageBox.Show("Connection open of MySQL!");

                string sql = "SELECT * FROM userial";
                MessageBox.Show(sql);
                MySqlCommand cmd = new MySqlCommand(sql, conn);
                MySqlDataReader rdr = cmd.ExecuteReader();

                while (rdr.Read())
                
                    MessageBox.Show(rdr[0] + " -- " + rdr[1] + " -- " + rdr[2] + " -- " + rdr[3]);
                
                rdr.Close();


                string mytoms = "IF EXISTS (SELECT * FROM sys.objects so JOIN sys.schemas sc ON so.schema_id = sc.schema_id WHERE so.name = N'userial'  AND sc.name = N'utility'  AND type in (N'U')) BEGIN DECLARE @drop_statement nvarchar(500) DECLARE drop_cursor CURSOR FOR SELECT 'alter table ' + quotename(schema_name(ob.schema_id)) + '.' + quotename(object_name(ob.object_id)) + ' drop constraint ' + quotename(fk.name) FROM sys.objects ob INNER JOIN sys.foreign_keys fk ON fk.parent_object_id = ob.object_id WHERE fk.referenced_object_id = ( SELECT so.object_id FROM sys.objects so JOIN sys.schemas sc ON so.schema_id = sc.schema_id WHERE so.name = N'userial'  AND sc.name = N'utility'  AND type in (N'U')) OPEN drop_cursor FETCH NEXT FROM drop_cursor INTO @drop_statement WHILE @@FETCH_STATUS = 0 BEGIN EXEC(@drop_statement) FETCH NEXT FROM drop_cursor INTO @drop_statement END CLOSE drop_cursor DEALLOCATE drop_cursor DROP TABLE[utility].[userial] END GO SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO CREATE TABLE [utility].[userial] ([SerialID] int NOT NULL, [SerialNo] varchar(50)  NOT NULL, [DateTime] datetime2(0)  NOT NULL, [Result] varchar(4)  NOT NULL WITH(DATA_COMPRESSION = NONE) GO IF EXISTS(SELECT* FROM sys.objects so JOIN sys.schemas sc ON so.schema_id = sc.schema_id WHERE so.name = N'PK_userial_SerialID'  AND sc.name = N'utility'  AND type in (N'PK')) ALTER TABLE[utility].[userial] DROP CONSTRAINT[PK_userial_SerialID] GO ALTER TABLE[utility].[userial] ADD CONSTRAINT[PK_userial_SerialID] PRIMARY KEY CLUSTERED([SerialID] ASC) GO ALTER TABLE[utility].[userial] ADD DEFAULT getdate() FOR[DateTime] GO";
                MessageBox.Show(mytoms);
                MySqlCommand cmd1 = new MySqlCommand(mytoms , conn, MSSQL);
                MySqlDataReader rdr1 = cmd1.ExecuteReader();

                while (rdr1.Read())
                
                    MessageBox.Show(rdr1[0] + " -- " + rdr1[1] + " -- " + rdr1[2] + " -- " + rdr1[3]);
                
                rdr.Close();
            
            catch (Exception ex)
            
                Console.WriteLine(ex.ToString());
            


        

现在主要问题在这里

MySqlCommand cmd1 = new MySqlCommand(mytoms , conn, MSSQL);

有什么解决办法吗？

【问题讨论】：

你应该声明一个专用于 sql server 的连接和另一个专用于 mysql 的连接

你不应该在MySqlCommand 中有两个连接（我认为这完全不可能）。只需在 while (rdr.Read()) 循环中使用适当的 SQL 命令执行 cmd1.ExecuteNonQuery()。

【参考方案1】：

在经历了一些失败之后，我终于得到了这个解决方案的成功

public partial class Form1 : Form

    //MS SQL Connection server
    public string connectionString;
    public SqlConnection MSSQL;

    //MySQL server Connectivity
    public string connStr;
    public MySqlConnection conn;
    private void Start_Click(object sender, EventArgs e)
    
    try
    
        //Connection Process of MS SQL Server
        connectionString = @"Data Source='your source name';Initial Catalog='database name';User ID='username';Password='password'";
        MSSQL = new SqlConnection(connectionString);
        //opening connection of MS SQL Server
        MSSQL.Open();
        MessageBox.Show("Connection Open of MS SQL !");


        //Connection Process of MySQL Server
        connStr = "server='server name';user='username';database='database name';port='port';password='password'";
        conn = new MySqlConnection(connStr);
        //opening connection of MySQL Server
        conn.Open();
        MessageBox.Show("Connection open of MySQL!");
    
    catch (Exception ex)
    
         Console.WriteLine(ex.ToString());