Parameters in SQL - Delphi 7

Question

I am using Delphi 7 and Access 2007.

I want to know can anyone show me how to use Parameters with SQL statements and ADO.

What is the necessary coding and

Answer 1

Simply set the query's SQL, and then populate the parameters. Use parameter names that make sense to you, of course; I've just used LastName and FirstName for examples. I've updated to use TADOQuery instead of just TQuery after your edit to the question.

ADOQuery1.SQL.Clear;
ADOQuery1.SQL.Add('SELECT * FROM MyTable');
ADOQuery1.SQL.Add('WHERE LastName = :LastName AND');
ADOQuery1.SQL.Add('FirstName = :FirstName');

// Populate the parameters and open it
ADOQuery1.Parameters.ParamByName('LastName').Value := 'Jones';
ADOQuery1.Parameters.ParamByName('FirstName').Value := 'James';
ADOQuery1.Open;
// Use query results

ADOQuery1.Close;
// Populate parameters with new values and open again
// Populate the parameters and open it
ADOQuery1.Parameters.ParamByName('LastName').Value := 'Smith';
ADOQuery1.Parameters.ParamByName('FirstName').Value := 'Sam';
ADOQuery1.Open;
// Use new query results

ADOQuery1.Close;