C#，如何使用查询进行搜索

Question

我想做搜索。我使用 C# 连接 MySQL 数据库。以及何时创建表之间的实体关系图。我想使用查询，例如通过客户的手机查找该特定分配属于特定客户。

我试试这个。

MySqlConnection connection = new MySqlConnection(MyConnectionString);
connection.Open();

try
{
    MySqlCommand cmd = connection.CreateCommand();


    cmd.CommandText = "SELECT *  FROM assignments  WHERE assignments.Customer_ID = customers.Customer_ID;
    //assignments and customers are tables
    MySqlDataAdapter adap = new MySqlDataAdapter(cmd);
    DataSet ds = new DataSet();
    adap.Fill(ds);
    dataGridView5.DataSource = ds.Tables[0].DefaultView;


}
catch (Exception)
{

    //throw;

    MessageBox.Show("Please complete correct the fields");
}

finally
{

    if (connection.State == ConnectionState.Open)
    {

        connection.Clone();

    }
}

有人可以帮助我吗？

Answer 1

您的查询似乎有误。您需要像这样正确连接表:

cmd.CommandText = "SELECT *  FROM assignments 
       inner join Customers on assignments.Customer_ID = customers.Customer_ID";