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<li class="level1"><a href="#topics">Topics:</a></li>
<li class="level1"><a href="#database-classes">Database Classes</a></li>
<li class="level2"><a href="#driver-layer">Driver Layer</a></li>
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<h1 class="title">SQL Programming</h1>
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<p>This overview assumes that you have at least a basic knowledge of SQL. You should be able to understand simple <tt>SELECT</tt>, <tt>INSERT</tt>, <tt>UPDATE</tt>, and <tt>DELETE</tt> statements. Although the <a href="qsqltablemodel.html">QSqlTableModel</a> class provides an interface to database browsing and editing that does not require a knowledge of SQL, a basic understanding of SQL is highly recommended. A standard text covering SQL databases is <i>An Introduction to Database Systems</i> (7th Ed.) by C. J. Date, ISBN 0201385902.</p>
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<h2>Topics:</h2>
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<li><a href="database.html">Database Classes</a></li>
<li><a href="sql-connecting.html">Connecting to Databases</a><ul>
<li><a href="sql-driver.html">SQL Database Drivers</a></li>
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<li><a href="sql-sqlstatements.html">Executing SQL Statements</a><ul>
<li><a href="sql-types.html">Data Types for Qt-supported Database Systems</a></li>
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<li><a href="sql-model.html">Using the SQL Model Classes</a></li>
<li><a href="sql-presenting.html">Presenting Data in a Table View</a></li>
<li><a href="sql-forms.html">Creating Data-Aware Forms</a></li>
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<a name="database-classes"></a>
<h2>Database Classes</h2>
<p>These classes provide access to SQL databases.</p>
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<tr class="odd topAlign"><td class="tblName"><p><a href="qsql.html">QSql</a></p></td><td class="tblDescr"><p>Contains miscellaneous identifiers used throughout the Qt SQL library</p></td></tr>
<tr class="even topAlign"><td class="tblName"><p><a href="qsqldatabase.html">QSqlDatabase</a></p></td><td class="tblDescr"><p>Represents a connection to a database</p></td></tr>
<tr class="odd topAlign"><td class="tblName"><p><a href="qsqldriver.html">QSqlDriver</a></p></td><td class="tblDescr"><p>Abstract base class for accessing specific SQL databases</p></td></tr>
<tr class="even topAlign"><td class="tblName"><p><a href="qsqldrivercreator.html">QSqlDriverCreator</a></p></td><td class="tblDescr"><p>Template class that provides a SQL driver factory for a specific driver type</p></td></tr>
<tr class="odd topAlign"><td class="tblName"><p><a href="qsqldrivercreatorbase.html">QSqlDriverCreatorBase</a></p></td><td class="tblDescr"><p>The base class for SQL driver factories</p></td></tr>
<tr class="even topAlign"><td class="tblName"><p><a href="qsqlerror.html">QSqlError</a></p></td><td class="tblDescr"><p>SQL database error information</p></td></tr>
<tr class="odd topAlign"><td class="tblName"><p><a href="qsqlfield.html">QSqlField</a></p></td><td class="tblDescr"><p>Manipulates the fields in SQL database tables and views</p></td></tr>
<tr class="even topAlign"><td class="tblName"><p><a href="qsqlindex.html">QSqlIndex</a></p></td><td class="tblDescr"><p>Functions to manipulate and describe database indexes</p></td></tr>
<tr class="odd topAlign"><td class="tblName"><p><a href="qsqlquery.html">QSqlQuery</a></p></td><td class="tblDescr"><p>Means of executing and manipulating SQL statements</p></td></tr>
<tr class="even topAlign"><td class="tblName"><p><a href="qsqlquerymodel.html">QSqlQueryModel</a></p></td><td class="tblDescr"><p>Read-only data model for SQL result sets</p></td></tr>
<tr class="odd topAlign"><td class="tblName"><p><a href="qsqlrecord.html">QSqlRecord</a></p></td><td class="tblDescr"><p>Encapsulates a database record</p></td></tr>
<tr class="even topAlign"><td class="tblName"><p><a href="qsqlrelationaltablemodel.html">QSqlRelationalTableModel</a></p></td><td class="tblDescr"><p>Editable data model for a single database table, with foreign key support</p></td></tr>
<tr class="odd topAlign"><td class="tblName"><p><a href="qsqlresult.html">QSqlResult</a></p></td><td class="tblDescr"><p>Abstract interface for accessing data from specific SQL databases</p></td></tr>
<tr class="even topAlign"><td class="tblName"><p><a href="qsqltablemodel.html">QSqlTableModel</a></p></td><td class="tblDescr"><p>Editable data model for a single database table</p></td></tr>
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<p>The SQL classes are divided into three layers:</p>
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<h3>Driver Layer</h3>
<p>This comprises the classes <a href="qsqldriver.html">QSqlDriver</a>, <a href="qsqldrivercreator.html">QSqlDriverCreator</a><T>, <a href="qsqldrivercreatorbase.html">QSqlDriverCreatorBase</a>, <a href="qsqldriverplugin.html">QSqlDriverPlugin</a>, and <a href="qsqlresult.html">QSqlResult</a>.</p>
<p>This layer provides the low-level bridge between the specific databases and the SQL API layer. See <a href="sql-driver.html">SQL Database Drivers</a> for more information.</p>
<a name="sql-api-layer"></a>
<h3>SQL API Layer</h3>
<p>These classes provide access to databases. Connections are made using the <a href="qsqldatabase.html">QSqlDatabase</a> class. Database interaction is achieved by using the <a href="qsqlquery.html">QSqlQuery</a> class. In addition to <a href="qsqldatabase.html">QSqlDatabase</a> and <a href="qsqlquery.html">QSqlQuery</a>, the SQL API layer is supported by <a href="qsqlerror.html">QSqlError</a>, <a href="qsqlfield.html">QSqlField</a>, <a href="qsqlindex.html">QSqlIndex</a>, and <a href="qsqlrecord.html">QSqlRecord</a>.</p>
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<h3>User Interface Layer</h3>
<p>These classes link the data from a database to data-aware widgets. They include <a href="qsqlquerymodel.html">QSqlQueryModel</a>, <a href="qsqltablemodel.html">QSqlTableModel</a>, and <a href="qsqlrelationaltablemodel.html">QSqlRelationalTableModel</a>. These classes are designed to work with Qt's <a href="model-view-programming.html">model/view framework</a>.</p>
<p>Note that to use any of these classes, a <a href="qcoreapplication.html">QCoreApplication</a> object must have been instantiated first.</p>
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