将值赋给mysql命令中的参数，但未返回正确的ID

Question

这是程序中执行的查询的示例：

        Int64 kooid = new Int64();
        myCommand.CommandText = ("SELECT kooiid FROM kooien where NummerExtern =?NummerExtern");
        myCommand.Parameters.Add("?NummerExtern", MySqlDbType.Int64).Value = kooi.Kooinr;
        kooid = Convert.ToInt64(myCommand.ExecuteScalar());
        return kooid;

这是餐桌化妆的一个例子

kooiid(int)| kooidlistppg(int)|quarantaine(tiny int) |idvogelsoort(int)|idvogelondersoort(int)| vasteoflossekooie(tiny int)| bezetofniet(tiny int)| idsponsor(int)| NummerExtern(int)

在您问我何时手动运行查询之前，它可以正常运行，但是当程序正确排序时，即使kooinr变量正确，查询也会向kooiid返回零

Answer 1

找到了解决方案

Int64 kooid = new Int64();
        myCommand.CommandText = ("Select kooiid from kooien where NummerExtern = ?NummerExtern");
        myCommand.Parameters.Add("?NummerExtern", MySqlDbType.Int64).Value = kooi.Kooinr;
        string kooidstring = myCommand.ExecuteScalar().ToString();
        kooid = Convert.ToInt64(kooidstring);
        return kooid;