创建然后使用查询中的参数 [英] Creating and then working with parameters in queries

问题描述

我正在编写一个小型 XAML/C#/MySQL 数据库，并希望创建一个接受参数的查询.但是，当我尝试创建它时，我设置的测试查询失败

I am writing a small XAML/C#/MySQL database and wanted to create a query that accepts parameters. However, the test query that I am setting up fails when I try to create it

    var con = new MySqlConnection(ClsVariables.StrDb);
    con.Open();
    var command = new MySqlCommand("", con);

command =
    new MySqlCommand("Create View r2_Add_Edit_View as SELECT era.contact_id, era.n_family FROM era WHERE era.contact_id = @ContactID", con)            command.ExecuteNonQuery();
    con.Close();

当我将 @ContactID 更改为特定数字时 - 它工作正常.

When I change the @ContactID to a specific number - it works fine.

之后我需要创建一个记录集，并将参数传递给它(但我可以在第二个问题中提出这个问题).

After that I will need to create a recordset, and pass the parameter to it (but I can ask that in a secondary question).

一如既往的感谢.

推荐答案

当我将 @ContactID 更改为特定数字时 - 它工作正常.

When I change the @ContactID to a specific number - it works fine.

好吧，您没有传递参数，因此只需将其添加到您的命令中即可:

Well, you don't pass the parameter, so just add it to your command:

public class MySqlConnector
{
    private readonly string _connString;

    public MySqlConnector(string connString)
    {
        _connString = connString;
    }

    private MySqlCommand _command;
    const string Sql = "Create View r2_Add_Edit_View as SELECT era.contact_id, era.n_family FROM era WHERE era.contact_id = @ContactID";

    public void CreateView(int contactId)
    {
        if(_command == null)
        {
            _command = new MySqlCommand();

            _command.CommandText = Sql;
            _command.Connection = _connString;
        }
        _command.Parameters.AddWithValue("@ContactID", contactId);
        _command.ExecuteNonQuery();
        _command.Close();
    }
}

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