Question

I have the following code:

As you can see, i need to pass a parameter to Field2, but i also need that parameter to be ablo to handle the “”all values” option, for example, if i assign “foo” to the parameter, the query will return every record where Field2 = “foo”… but i also want to be able to pass a wildcard, or something to tell that parameter to give all values as result.

MyDataset dataset = new MyDataset();
SqlConnection objConnection = new SqlConnection(_connectionstring);
SqlDataAdapter objDataAdapter = new SqlDataAdapter();
objDataAdapter.SelectCommand = new SqlCommand();
objDataAdapter.SelectCommand.Connection = objConnection;
objDataAdapter.SelectCommand.CommandText =
"SELECT Field1, Field2, Field3 FROM Table WHERE (Field2 = @Field2)";
objDataAdapter.SelectCommand.CommandType = CommandType.Text;
objDataAdapter.SelectCommand.Parameters.AddWithValue("@Field2", txtBoxField2.Text);
objDataAdapter.Fill(dataset.Table);
this.DataContext = dataset.Table.DefaultView;

Thank you in advance.

Answer 1

If you’re building up the SQL like that within your C# code, then just put an if condition in your C# logic to not include the WHERE clause in the instance you want to return all records. This would create a different SQL statement, so would be OK for performance/execution plan-wise.

If you’re going to be using a sproc, you could try this approach:

IF (@Field2 = 'SomeWildcardValue')
    SELECT Field1, Field2, Field3 FROM SomeTable
ELSE
    SELECT Field1, Field2, Field3 FROM SomeTable WHERE Field2 = @Field2

Or even, keep them completely separate, create one sproc to return ALL, and one to return based on Field2 search. Although if you have a larger number of parameters, this can soon mount up!