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+<td><h1>CodeIgniter User Guide Version 1.6.0</h1></td>
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+<a href="../index.html">User Guide Home</a> ›
+<a href="index.html">Database Library</a> ›
+Database Utility Class
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+<div id="content">
+
+<h1>Database Forge Class</h1>
+
+<p>The Database Forge Class contains functions that help you manage your database.</p>
+
+<h3>Table of Contents</h3>
+
+<ul>
+<li><a href="#init">Initializing the Forge Class</a></li>
+<li><a href="#create">Creating a Database</a></li>
+<li><a href="#drop">Dropping a Database</a></li>
+<li><a href="#add_field">Adding Fields</a></li>
+<li><a href="#add_key">Adding Keys</a></li>
+<li><a href="#create_table">Creating a Table</a></li>
+<li><a href="#drop_table">Dropping a Table</a></li>
+<li><a href="#modifying_tables">Modifying a Table</a></li>
+</ul>
+
+
+<h2><a name="init"></a>Initializing the Forge Class</h2>
+
+<p class="important"><strong>Important:</strong> In order to initialize the Forge class, your database driver must
+already be running, since the forge class relies on it.</p>
+
+<p>Load the Forge Class as follows:</p>
+
+<code>$this->load->dbforge()</code>
+
+<p>Once initialized you will access the functions using the <dfn>$this->dbforge</dfn> object:</p>
+
+<code>$this->dbforge->some_function()</code>
+<h2><a name="create"></a>$this->dbforge->create_database('db_name')</h2>
+
+<p>Permits you to create the database specified in the first parameter. Returns TRUE/FALSE based on success or failure:</p>
+
+<code>if ($this->dbutil->create_database('my_db'))<br />
+{<br />
+ echo 'Database created!';<br />
+}</code>
+
+
+
+
+<h2><a name="drop"></a>$this->dbforge->drop_database('db_name')</h2>
+
+<p>Permits you to drop the database specified in the first parameter. Returns TRUE/FALSE based on success or failure:</p>
+
+<code>if ($this->dbutil->drop_database('my_db'))<br />
+{<br />
+ echo 'Database deleted!';<br />
+}</code>
+
+
+<h1>Creating and Dropping Tables</h1>
+<p>There are several things you may wish to do when creating tables. Add fields, add keys to the table, alter columns. CodeIgniter provides a mechanism for this.</p>
+<h2><a name="add_field" id="add_field"></a>Adding fields</h2>
+<p>Fields are created via an associative array. Within the array you must include a 'type' key that relates to the datatype of the field. For example, INT, VARCHAR, TEXT, etc. Many datatypes (for example VARCHAR) also require a 'constraint' key.</p>
+<p><code>$fields = array(<br />
+ 'users' => array(<br />
+ 'type' => 'varchar',<br />
+ 'constraint' => '100',<br />
+ ),<br />
+ );<br />
+ <br />
+// will translate to "users VARCHAR(100)" when the field is added.</code></p>
+<p>Additionally, the following key/values can be used:</p>
+<ul>
+ <li>unsigned/true : to generate "UNSIGNED" in the field definition</li>
+ <li>default/value : to generate a default value in the field definition</li>
+ <li>null/true : to generate "NULL" in the field definition. Without this, the field will default to "NOT NULL"</li>
+ <li>auto_increment/true : generates an auto_increment flag on the field. Note that the field type must </li>
+ </ul>
+<p><code>$fields = array(<br />
+ 'blog_id' => array(<br />
+ 'type' => 'INT',<br />
+ 'constraint' => 5, <br />
+ 'unsigned' => TRUE,<br />
+ 'auto_increment' => TRUE<br />
+ ),<br />
+ 'blog_title' => array(<br />
+ 'type' => 'VARCHAR',<br />
+ 'constraint' => '100',<br />
+ ),<br />
+ 'blog_author' => array(<br />
+ 'type' =>'VARCHAR',<br />
+ 'constraint' => '100',<br />
+ 'default' => 'King of Town',<br />
+ ),<br />
+ 'blog_description' => array(<br />
+ 'type' => 'TEXT',<br />
+ 'null' => TRUE,<br />
+ ),<br />
+ );<br />
+ );</code></p>
+<p>After the fields have been defined, they can be added using <dfn>$this->dbforge->add_field($fields);</dfn> followed by a call to the <dfn>create_table()</dfn> function.</p>
+<h3>$this->dbforge->add_field()</h3>
+<p>The add fields function will accept the above array.</p>
+<h3>Passing strings as fields</h3>
+<p>If you know exactly how you want a field to be created, you can pass the string into the field definitions with add_field()</p>
+<p><code>$this->dbforge->add_field("label varchar(100) NOT NULL DEFAULT 'default label'");</code></p>
+<p class="important">Note: Multiple calls to <dfn>add_field()</dfn> are cumulative.</p>
+<h3>Creating an id field</h3>
+<p>There is a special exception for creating id fields. A field with type id will automatically be assinged as an INT(9) auto_incrementing Primary Key.</p>
+<p><code>$this->dbforge->add_field('id');<br />
+ // gives id INT(9) NOT NULL AUTO_INCREMENT</code></p>
+<h2><a name="add_key" id="add_key"></a>Adding Keys</h2>
+<p>Generally speaking, you'll want your table to have Keys. This is accomplished with <dfn>$this->dbforge->add_key('field')</dfn>. An optional second parameter set to TRUE will make it a primary key. Note that <dfn>add_key()</dfn> must be followed by a call to <dfn>create_table()</dfn>.</p>
+<p><code>$this->dbforge->add_key('blog_id', TRUE);<br />
+ // gives PRIMARY KEY (blog_id)<br />
+ <br />
+ $this->dbforge->add_key('blog_name');<br />
+ // gives KEY (blog_name)</code></p>
+<h2><a name="create_table" id="create_table2"></a>Creating a table</h2>
+<p>After fields and keys have been declared, you can create a new table with</p>
+<p><code>$this->dbforge->create_table('table_name')<br />
+// gives CREATE TABLE table_name</code></p>
+<p>An optional second parameter set to TRUE adds an "IF NOT EXISTS" clause into the definition</p>
+<p><code>$this->dbforge->create_table('table_name')<br />
+// gives CREATE TABLE IF NOT EXISTS table_name</code></p>
+<h2><a name="drop_table" id="drop_table"></a>Dropping a table</h2>
+<p>Executes a DROP TABLE sql</p>
+<p><code>$this->dbforge->drop_table('table_name')<br />
+// gives DROP TABLE IF EXISTS table_name</code></p>
+<h1><a name="modifying_tables" id="drop_table2"></a>Modifying Tables</h1>
+<h2>$this->dbforge->add_column()</h2>
+<p>The add_column() function is used to modify an existing table. It accepts the same field array as above, and can be used for an unlimited number of additional fields.</p>
+<p><code>$fields = array(<br />
+ 'preferences' => array('type' => 'TEXT')<br />
+);<br />
+$this->dbforge->add_column('table_name', $fields);<br />
+<br />
+// gives ALTER TABLE sites ADD preferences TEXT</code></p>
+<h2>$this->dbforge->drop_column()</h2>
+<p>Used to remove a column from a table. </p>
+<p><code>$this->dbforge->drop_column('table_name', 'column_to_drop');</code></p>
+<h2>$this->dbforge->modify_column()</h2>
+<p>The usage of this function is identical to add_coumn(), except it alters an existing column rather than adding a new one. In order to use it you must add a "name" key into the field defining array.</p>
+<p><code>$fields = array(<br />
+ 'old_name' => array(<br />
+ 'name' => 'new_name',<br />
+ 'type' => 'TEXT',<br />
+ ),<br />
+);<br />
+$this->dbforge->modify_column('sites', $fields);<br />
+ <br />
+ // gives ALTER TABLE sites CHANGE old_name new_name TEXT </code></p>
+<p> </p>
+</div>
+<!-- END CONTENT -->
+
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