This post is a part 12 of Creating a WordPress Admin Theme post series.
In this article I will show you how you can create wordpress tables and also how to store data in wordpress tables. WordPress can be used to store arbitrary data(data not related to wordpress settings, posts/pages, profile, wordpress functionality etc).
What is WordPress Tables
WordPress tables are MySQL tables created using WordPress API and their name starts with WordPress defined prefix.
WordPress $wpdb global object
$wpdb global object is used to retrieve the prefix of wordpress tables, add rows to wordpress tables and get rows from wordpress tables.
Retrieving Prefix
echo $wpdb->prefix;
For multisite wordpress installation prefix property returns different prefixes for each site in the network.
Adding Row
The insert method has 3 parameters, the table name, an array representing the row and the columns data format.
Retrieving Rows
$results = $wpdb->get_results($wpdb->prepare('SELECT * FROM tablename WHERE name="narayan"'));
Iterating Result
foreach ($results as $row) {
echo $row->name;
echo $row->ID;
}
echo $row->name;
echo $row->ID;
}
dbDelta function
dbDelta function is used to create WordPress tables.
$table_name = $wpdb->prefix . "tablename";
$sql = "CREATE TABLE $table_name (
id INT NOT NULL ,
name varchar(255) NOT NULL
);";
/*To use this function you must include it.*/
require_once( ABSPATH . 'wp-admin/includes/upgrade.php' );
dbDelta( $sql );
$sql = "CREATE TABLE $table_name (
id INT NOT NULL ,
name varchar(255) NOT NULL
);";
/*To use this function you must include it.*/
require_once( ABSPATH . 'wp-admin/includes/upgrade.php' );
dbDelta( $sql );
If the table exists then dbDelta will not create a table, it will just ignore.
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