introduction to sqlite in adobe air

Introduction to SQLitein Adobe AIRPeter Elst - Flash Platform Consultant

■ Embedded SQL Database Engine

■ Implements most of SQL92

■ Light-weight, cross-platform, open source

■ No setup, configuration or server required

■ Each database is contained within a single file

Why SQLite in Adobe AIR?

1. Create a File reference

2. Create an instance of flash.data.SQLConnection and flash.data.SQLStatement

3. Open the database connection

4. Specify the connection and SQL query to run

5. Run SQLStatement.execute()

How do you use it?

import flash.filesystem.File;import flash.data.*;

var dbFile:File = File.applicationStorageDirectory.resolvePath("contacts.db");

var sqlConn:SQLConnection = new SQLConnection();var sqlStatement:SQLStatement = new SQLStatement();

sqlConn.open(dbFile);

sqlStatement.sqlConnection = sqlConn;sqlStatement.text = "SELECT * FROM contacts";sqlStatement.execute();

var result:Array = sqlStatement.getResult().data;

How do you use it?

Synchronous versus Asynchronous

■ Synchronous - blocks application until result is available

var sqlConn:SQLConnection = new SQLConnection();sqlConn.open(dbFile);

var result:SQLResult = sqlConn.getResult().result;

■ Asynchronous - uses events and event listeners

var sqlConn:SQLConnection = new SQLConnection();

sqlConn.addEventListener(SQLResultEvent.RESULT, onSQLResult);sqlConn.addEventListener(SQLResultEvent.ERROR, onSQLError);

sqlConn.openAsync(dbFile);

■ Connects to the database file

■ Provides events for asynchronous use

■ Schema access

flash.data.SQLConnection

■ Executes a SQL query on the specified database connection

■ Provides events for asynchronous use

■ Supports result paging

flash.data.SQLStatement

■ NULL - NULL value (null)

■ INTEGER - signed integer (int)

■ REAL - floating point (Number)

■ TEXT - UTF16 text string (String)

■ BLOB - blob of data

Storage types

■ The parameters feature protects your SQL statements from SQL injection

var sqlStatement:SQLStatement = new SQLStatement();sqlStatement.sqlConnection = sqlConn;sqlStatement.text = "SELECT * FROM contacts WHERE id = @ID";sqlStatement.parameters["@ID"] = someVariable;sqlStatement.execute();

■ You can use the @ or : symbol to denote a parameter to be replaced, works both string based as index based

sqlStatement.parameters[0] = someVariable;

SQLStatement Parameters

■ Paging allows you to limit the amount of rows you get returned when doing a select operation

var sqlStatement:SQLStatement = new SQLStatement();sqlStatement.sqlConnection = sqlConn;sqlStatement.text = "SELECT * FROM contacts";sqlStatement.execute(10);

■ You can get the next batch of rows returned by calling the next method on the SQLStatement instance

sqlStatement.next();

Result Paging

■ SQLResult.data - array of objects for each row of the result

■ SQLResult.complete - returns a boolean indicating whether or not the full result was shown

■ SQLResult.lastInsertRowID - return id for the last row that was inserted

■ SQLResult.rowsAffected - number of rows affected by an insert, update or delete operation

flash.data.SQLResult

■ Transactions allow multiple SQL statements to run within one write operation to the database

■ Much more optimized way of handling large insert operations, allows rollback of the complete transaction if an error occurs

var sqlStatement:SQLStatement = new SQLStatement();sqlStatement.sqlConnection = sqlConn;sqlStatement.text = "INSERT into contacts VALUES (@NAME, @EMAIL)";

sqlConn.begin();for(var i:uint=0; i<contacts.length; i++) { sqlStatement.parameters["@NAME"] = contacts[i].name; sqlStatement.parameters["@EMAIL"] = contacts[i].email; sqlStatement.execute();}sqlConn.commit();

Transactions

■ Allows you to introspect tables, views, columns, indices, triggers

var sqlConn:SQLConnection = new SQLConnection();sqlConn.open(dbFile);

sqlConn.loadSchema();var result:SQLSchemaResult = sqlConn.getSchemaResult();

var table:SQLTableSchema = result.tables[0];var column:SQLColumnSchema = table.columns[0];

trace(column.name);// returns name of the first column in the first table

Database Schema

Demo time

■ Adobe AIR Developer Centerwww.adobe.com/devnet/air/

■ AdvancED AIR Applications (coming soon)

■ www.peterelst.com | onair@peterelst.com

■ www.adobeusergroup.be

Resources