Symbian SQL Overview

This document introduces you to the Symbian platform implementation of the Structured Query Language(SQL).

Purpose

SQL is: the syntax for creating, modifying and deleting databases and the data they contain; an engine or server that understands that syntax; the commands and operations that allow the SQL engine to process the syntatical elements. Developers who know one variant of SQL can easily work in another.

Required background

Relational databases, the SQL query language, database programming fundamentals.

Key concepts/terms

The SQL component includes these key concepts:

Relational database

A structured collection of data organised as tables (relations).
SQL

A standard language for querying relational databases.
Security policy

A specification of user permissions on a database.

Architectural relationships

The SQL component is a free standing component that can be accessed by any application and from anywhere in Symbian platform.

It is has a client-server architecture. Applications interface with the client API. The server side is an executable running in its own process and is not directly accessible to client applications. It can only be reached via the client-side interface.

Figure: This image depicts the client / server nature of Symbian SQL

API summary

The SQL component client consists of three APIs which are used to access, query and secure a database.

SQL APIs

The SQL database API, which you use to access a database.
The SQL statement API, which you use to query a database.
The SQL security policy API, which you use to create a secure database.

API	Description
`RSqlDatabase`	The SQL database API
`RSqlStatement`	The SQL statement API
`RSqlSecurityPolicy`	The SQL security policy API

Typical uses

Relational databases and the SQL query language are fundamentals of application development with numerous uses.

SQL Users

Application developers needing to access databases.

SQL tasks

The SQL component is used to:

create,
delete,
access,
query, and
modify relational databases.

Creating and deleting a relational database

The SQL component is used to create and delete relational databases. They may be secure or insecure.

Accessing a relational database

Use the SQL component to open and close databases and to attach a secondary database to a primary one.

Querying and modifying a relational database

Use the SQL component to query a database using SQL. Queries can read, write, modify and delete data in a database.