In the previous article, we discussed how to use the ADO components and we created an example program using an ADOTable component. In this article we are going to discuss the ADOQuery component and how it can help us deal with data manipulation in an ADO database.
The ADOQuery Component - ADOQuery Component (Page 2 of 4 )
The ADOQuery component helps database application developers to fetch information from single/multiple tables in an ADO database though the use of SQL.
There are two kinds of SQL statements:
DDL (Data Definition Language): these include CREATE TABLE and ALTER INDEX.
DML (Data Manipulation Language): these include SELECT, UPDATE and DELETE.
The most common statement, however, is the SELECT statement, which produces a view similar to what we have seen when using the Table component in my previous article. The SQL that you use here must be compatible with the ADO driver. This is because there are differences between how you write SQL statements in MySQL/MSSQL and Access. The differences are not that difficult to overcome if you’ve been working with SQL before.
As with the ADO Table component, you access a database through the connection string. In this article I’m not going to use any database aware components, so using a datasource component will not be necessary. The Query component does not have a TableName property, like the ADO Table component.
Delphi-Kylix 
Using Delphi with ADO
