查询字符串数据类型不匹配

Question

I'm using OLEDB to query an excel file using date time picker but I keep getting a Data type mismatch in cireria expression error.

The format in excel for the date is "6/08/2012 10:00"

        DateTime time = dateTimePicker1.Value;            

        MyCommand = new OleDbDataAdapter("select * from [CR$] where ([Req Start Date] >='" + time + "')", MyConnection);



        DtSet = new System.Data.DataSet();
        MyCommand.Fill(DtSet);


        bindingSource1 = new BindingSource();
        bindingSource1.DataSource = DtSet;
        bindingSource1.DataMember = DtSet.Tables[0].TableName;
        dataGridView1.DataSource = bindingSource1;

        MyConnection.Close();

Answer 1

You are passing time to the query as a string, so you could ToString() it to make it work:

MyCommand = new OleDbDataAdapter("select * from [CR$] where ([Req Start Date] >='" + time.ToString("%M/dd/yyyy HH:mm") + "')", MyConnection);

But you really should make it a parameter. Plus, it's safer that way.

    using (OleDbConnection connection = new OleDbConnection(yourConnectionString))
    {
        OleDbDataAdapter adapter = new OleDbDataAdapter("select * from [CR$] where [Req Start Date] >= ?", connection);
        adapter.SelectCommand.Parameters.Add("@p1", OleDbType.Date);
        adapter.SelectCommand.Parameters["@p1"].Value = time;

        try
        {
            connection.Open();
            adapter.Fill(DtSet);
        }
        catch (Exception ex)
        {
            //handle error
        }
    }

Find out more: OleDbParameter Class

Answer 2

Create an OleDbCommand and pass the value in as a parameter. Then use the Command as a parameter for the OleDbAdapter constructor...

string queryString = "select * from [CR$] where ([Req Start Date] >= ?)";
OleDbCommand command = new OleDbCommand(queryString, connection);
command.Parameters.Add("@p1", OleDbType.DateTime).Value = time;
MyCommand = new OleDbDataAdapter(queryString, MyConnection);