c# 運行時系統無效操作異常 MYSQL

Question

大家好，我想在數據表上顯示從 Mysql 到 c# 表格的所有數據，但我總是得到這個異常“System.InvalidOperationException：'Fill：”

完整代碼：

    public void testing()
    {

        DBConnect dbc = new DBConnect();
        dbc.OpenConnection();
        string connectionString;
        connectionString = "SERVER=" + server + ";" + "DATABASE=" +
        database + ";" + "UID=" + uid + ";" + "PASSWORD=" + password + ";";

        string query1 = "select * from info;";

        MySqlCommand commander = new MySqlCommand(query1, connection);

        MySqlDataAdapter searcher = new MySqlDataAdapter(commander);

        DataTable table = new DataTable();
        dataGridView1.DataSource = GetData(connectionString, query1);
    }

    public DataTable GetData(string connectionString, string query1)
    {
        using (var connection = new MySqlConnection(connectionString))
        {
            using (var command = new MySqlCommand(query1, connection))
            using (var reader = command.ExecuteReader())
            {
                var dataTable = new DataTable();
                dataTable.Load(reader);
                return dataTable;
            }
        }
    }

這是我的完整代碼，我仍然得到“連接必須有效且打開”

Answer 1

這是一個使用MySql.Data package 的示例，希望對您有用：

    using var con = new MySqlConnection(/*connection string goes here*/);
    con.Open();

    using var command = new MySqlCommand(/*query goes here*/, con);
    using var reader = await command.ExecuteReaderAsync();

    while (await reader.ReadAsync())
    {
        // do your stuff here
    }

Answer 2

您的方法應該以這種方式工作：

public DataTable GetData(string connectionString, string query)
{
    using (var connection = new MySqlConnection(connectionString))
    {
        connection.Open();
        using (var command = new MySqlCommand(query, connection))
        using (var reader = command.ExecuteReader())
        {
            var dataTable = new DataTable();
            dataTable.Load(reader);
            return dataTable;
        }
    }
}