C# MySQL 查询不工作

Question

错误信息是，

Connection must be valid and open.

这段代码有错吗？我该如何解决这个问题？

string strConn = "server = localhost; user = root; database = ****; port = 3306; password = ****; Charset = utf8";
using (MySqlConnection conn = new MySqlConnection(strConn))
{
    MySqlCommand insertCommand = new MySqlCommand();

    conn.Open();

    for (int i = 0; i < 10; i++)
    {
        insertCommand.CommandText = "INSERT INTO master (col_name, col_code)" +
        " SELECT * from (select '" + _name[i] + "', '" + _code[i] + "') as tmp" +
        " WHERE NOT EXISTS (" +
        " SELECT col_code FROM master WHERE col_code = '" + _name[i] + "') limit 1;";

        insertCommand.ExecuteNonQuery();
    }
    conn.Close();
}

Answer 1

在您的for 循环 之前需要为您的CommandObject 设置连接，例如:

InsertCommand.Connection = conn;