This article, the first of three parts, shows you how to access and change database content using Delphi and ADO. Accessing data both with and without data aware components is covered.
Using Delphi with ADO - Accessing Database Content (Page 2 of 4 )
Delphi 7, which I'm using for this article, ships with a host of ADO components, located on the ADO tab. There you will find ADOTable, ADOQuery, and so on. These are mostly referred to as Datasets. There are two ways to access data in a database using ADO:
Through Data Aware components located on the Data Controls tab. These components connect to a dataset through a datasource, and enable you to view the contents of a database. The components also enable you to manipulate records in a database without writing a single line of code. The downside of this approach is:
They use a lot of memory, compared to ordinary components.
They are not very flexible, and therefore not suitable for most real world database applications.
Through ordinary components, programmatically. This approach gives you more flexibility and greatly improves the chances of you creating effective real world database applications.
To access database content in Delphi, we need what is called a connection string. A connection string tells the application where the database is located on your hard disk. This property is available in all ADO datasets. If you develop your applications with data aware components, you are going to need a datasource component. This component is located on the Data Access tab, and acts as a connector that connects datasets (for example ADOTable) to a data aware component, such as a DBGrid. In the example below, I will demonstrate how the components are connected together.
Delphi-Kylix 
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