查询在Access中工作，但不在我的程序中。为什么？

Question

我有这个查询设置在我的应用程序工作，通过我的数据库搜索工作。我把这个查询放入Access，它工作正常。但是，当我把它放到我的程序中时，表中有0个条目。你能帮忙吗？

private async Task FilterDB() 
     { 
      List<string> Filter = new List<string>(); 

      if (CardNameCheck.IsChecked == true) 
       Filter.Add("*" + CardNameBox.Text + "*"); 
      else 
       Filter.Add("*"); 

      if (CardExpanCheck.IsChecked == true) 
       Filter.Add("*" + CardExpanBox.Text + "*"); 
      else 
       Filter.Add("*"); 

       OleDbConnection DBCon = new OleDbConnection(@"Provider=Microsoft.Jet.OLEDB.4.0; Data Source=" + Properties.Settings.Default.DatabaseLocation); 
       await DBCon.OpenAsync(); 

       OleDbDataAdapter CardDA = new OleDbDataAdapter("SELECT * FROM Cards WHERE Name like '" + Filter[0] + "' and Expansion like '" + Filter[1] + "'", DBCon); 
       DataSet CardDS = new DataSet(); 
       CardDA.Fill(CardDS); 
       DBCon.Close(); 

Answer 1

我试过你的代码并修改了一下。适用于Access2003 .mdb格式。

OleDbConnection DBCon = new OleDbConnection(@"Provider=Microsoft.Jet.OLEDB.4.0; Data Source=(k:\mydatabases\mydatabase.mdb"); 
DBCon.Open(); 

// Create a select Command - you need System.Data.OleDb and System.Data for this 

OleDbCommand selectCommand = new OleDbCommand(); 
// define the CommandText with two parameters @Filter1 and @Filter2 
selectCommand.CommandText = "SELECT * FROM Cards WHERE Name like @Filter1 and Expansion like @Filter2"; 

selectCommand.Connection = DBCon; 

// Create two string/VarChar Parameters - 
// the following is a standard I commonly use 
// for string/varchar; you might also use OleDbType.NVarChar 
OleDbParameter param01 = new OleDbParameter(); 
param01.ParameterName = "Filter1"; 
param01.DbType = DbType.AnsiString; 
param01.OleDbType = OleDbType.VarChar; 
param01.SourceVersion = DataRowVersion.Current; 
param01.SourceColumn = "Name"; 
// provide them with values - I used text boxes for input 
// use '%' for like statement - if no parameter provided use single '%' only 
if (txtFilter1.Text.ToString().Equals("")) 
{ 
    param01.Value = '%'; 
} 
else 
{ 
    param01.Value = '%' + txtFilter1.Text.ToString() + '%'; 
} 
// add the parameter to the SelectCommand 
selectCommand.Parameters.Add(param01); 

// same goes for the second parameter 
OleDbParameter param02 = new OleDbParameter(); 
param02.ParameterName = "Filter2"; 
param02.DbType = DbType.AnsiString; 
param02.OleDbType = OleDbType.VarChar; 
param02.SourceVersion = DataRowVersion.Current; 
param02.SourceColumn = "Expansion"; 
if (txtFilter2.Text.ToString().Equals("")) 
{ 
    param02.Value = '%'; 
} 
    else 
{ 
    param02.Value = '%' + txtFilter2.Text.ToString() + '%'; 
} 
selectCommand.Parameters.Add(param02); 

OleDbDataAdapter CardDA = new OleDbDataAdapter(); 
// tell the DataAdapter to use a SelectCommand 
CardDA.SelectCommand = selectCommand; 
CardDA.GetFillParameters(); // actually not sure if you need this but does no harm either 
DataSet CardDS = new DataSet(); 
CardDA.Fill(CardDS, "TargetTable"); 
DBCon.Close(); 

foreach(DataRow row in CardDS.Tables["TargetTable"].Rows) 
{ 
    // do something ; 
} 

祝你好运！