尝试开发Windows 8.1商店应用。除了其他困难之外,我还需要在where子句中使用两个参数从sqlite数据库中检索记录。我可以使用where子句中的一个参数成功查询,但是当我尝试使用两个参数时它会崩溃。这是我的代码:
public string SaveMaint(MaintViewModel Maintenance)
{
string result = string.Empty;
using (var db = new SQLite.SQLiteConnection(App.DBPath))
{
string change = string.Empty;
try
{
var existingmaintenance = db.Query<maintenance> ("select * from maintenance where VehID = ? AND MaintID = ?", new String[] {Maintenance.Maintid, Maintenance.Vehicleid});
// var existingmaintenance = (db.Table<maintenance>().Where
// (c => c.MaintID == Maintenance.Maintid).SingleOrDefault());
if (existingmaintenance != null)
{
existingmaintenance.VehID = Maintenance.Vehicleid;
existingmaintenance.MaintID = Maintenance.Maintid;
existingmaintenance.ServiceDate = Maintenance.Servicedate;
existingmaintenance.ServiceCost = Maintenance.Servicecost;
existingmaintenance.ServiceLocation = Maintenance.Servicelocation;
existingmaintenance.ServiceNote = Maintenance.Servicenote;
existingmaintenance.ServiceOdom = Maintenance.Serviceodom;
int success = db.Update(existingmaintenance);
}
else
{
int success = db.Insert(new maintenance()
{
VehID = Maintenance.Vehicleid,
MaintID = Maintenance.Maintid,
ServiceDate = Maintenance.Servicedate,
ServiceCost = Maintenance.Servicecost,
ServiceLocation = Maintenance.Servicelocation,
ServiceNote = Maintenance.Servicenote,
ServiceOdom = Maintenance.Serviceodom
});
}
result = "Success";
}
catch
{
result = "This project was not saved.";
}
}
return result;
}
请参阅定义existingmaintenance
变量的行。这行的注释版本工作正常。当我用两个参数查询替换变量定义时(使用不同的方法获得,因为我无法弄清楚如何向Table查询方法添加第二个参数),它会崩溃。
感谢您提供任何帮助。对不起,我只知道自己在做什么。
答案 0 :(得分:12)
假设您使用SQLite-Net作为ORM,您可以在查询后传递参数。据我所知,没有像你的例子那样支持匿名类。试试这个:
var existingmaintenance = db.Query<maintenance>(
"select * from maintenance where VehID = ? AND MaintID = ?",
Maintenance.Vehicleid, Maintenance.Maintid).FirstOrDefault();
您也可以使用linq查询,如下所示:
var existingmaintenance = db.Table<maintenance>().Where
(c => c.VehID == Maintenance.Vehicleid &&
c.MaintID == Maintenance.Maintid).FirstOrDefault();
答案 1 :(得分:0)
试试这个
我希望这两个Id都是数据库中的int
var existingmaintenance = db.Query<maintenance> ("select * from maintenance where VehID = " + Maintenance.Maintid + " AND MaintID = " + Maintenance.Vehicleid ).FirstOrDefault();