Question

Found very strange behavior of MS Access database when running queries from c#. It appears that if query in MS Access contains “like” statement it will not return its result to Oledb. If anyone knows how to solve this I’ll be very grateful. c# code:

DataTable GetAccessData(string FileName, string Password)
    {
        Query = "select * from [qry_1]";
        DataTable DT = access2dt
            (
            FileName,Password,Query);

        MessageBox.Show(Query);
        if (DT == null || DT.Rows.Count <= 1) throw new Exception("Data not found");
        else return DT;
    }

public static DataTable access2dt(string filename, string password, string query)
{
    string conString = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + filename + ";Jet OLEDB:Database Password=" + password;
    OleDbConnection mycon;
    mycon = new OleDbConnection(conString);

    if (mycon.State == ConnectionState.Closed)
    {
        mycon.Open();
    }
    try
    {
        OleDbCommand accessCommand = new OleDbCommand();
        System.Data.DataTable dt = new System.Data.DataTable();
        accessCommand = new OleDbCommand(query, mycon);

        using (OleDbDataReader myReader = accessCommand.ExecuteReader())
        {
            DataTable myTable = new DataTable();
            myTable.Load(myReader);
            return myTable;
        }
    }
    finally
    {
        mycon.Close();
    }

}

And query [qry_1] saved in MS Access database looks like this:

SELECT tbl_MAPPING_GICM_AoA.[Type of expense]
FROM tbl_USGAAP_ALL_TRANS, tbl_MAPPING_GICM_AoA
WHERE tbl_USGAAP_ALL_TRANS.[Account]=[tbl_MAPPING_GICM_AoA].[Natural Account]
AND tbl_USGAAP_ALL_TRANS.[Created By] NOT IN (SELECT [Created by / User ID] FROM tbl_GICM_AoA_EXCL_FACTOR1)
AND tbl_USGAAP_ALL_TRANS.[Je Source] NOT IN (SELECT [JE SOURCE] FROM tbl_GICM_AoA_EXCL_FACTOR2)
AND tbl_USGAAP_ALL_TRANS.[Je Category] NOT IN (SELECT [JE CATEGORY] FROM tbl_GICM_AoA_EXCL_FACTOR3)
AND (tbl_USGAAP_ALL_TRANS.[Account] LIKE '4*' OR tbl_USGAAP_ALL_TRANS.[Account] LIKE '5*'  OR tbl_USGAAP_ALL_TRANS.[Account] LIKE '6*' )

So when i run it in Access it works just fine but when i call this query from c# i get “Data not found” exception. If I remove the last string (with LIKE) in query everything starts working

Answer 1

Try replacing the wildcard character. Access uses ‘*’, but using OLEDB you will need to use ‘%’ as the wildcard.