check_column() WordPress Function

The check_column() function is used to check if a given column exists in a database table. This function is useful when you need to programmatically add or remove columns from a database table.

check_column( string $table_name, string $col_name, string $col_type, bool $is_null = null, mixed $key = null, mixed $default_value = null, mixed $extra = null ) #

Checks that database table column matches the criteria.


Description

Uses the SQL DESC for retrieving the table info for the column. It will help understand the parameters, if you do more research on what column information is returned by the SQL statement. Pass in null to skip checking that criteria.

Column names returned from DESC table are case sensitive and are listed: Field Type Null Key Default Extra


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Parameters

$table_name

(string)(Required)Database table name.

$col_name

(string)(Required)Table column name.

$col_type

(string)(Required)Table column type.

$is_null

(bool)(Optional) Check is null.

Default value: null

$key

(mixed)(Optional) Key info.

Default value: null

$default_value

(mixed)(Optional) Default value.

Default value: null

$extra

(mixed)(Optional) Extra value.

Default value: null


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Return

(bool) True, if matches. False, if not matching.


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Source

File: wp-admin/install-helper.php

function check_column( $table_name, $col_name, $col_type, $is_null = null, $key = null, $default_value = null, $extra = null ) {
	global $wpdb;

	$diffs   = 0;
	$results = $wpdb->get_results( "DESC $table_name" );

	foreach ( $results as $row ) {

		if ( $row->Field === $col_name ) {

			// Got our column, check the params.
			if ( ( null !== $col_type ) && ( $row->Type !== $col_type ) ) {
				++$diffs;
			}
			if ( ( null !== $is_null ) && ( $row->Null !== $is_null ) ) {
				++$diffs;
			}
			if ( ( null !== $key ) && ( $row->Key !== $key ) ) {
				++$diffs;
			}
			if ( ( null !== $default_value ) && ( $row->Default !== $default_value ) ) {
				++$diffs;
			}
			if ( ( null !== $extra ) && ( $row->Extra !== $extra ) ) {
				++$diffs;
			}

			if ( $diffs > 0 ) {
				return false;
			}

			return true;
		} // End if found our column.
	}

	return false;
}


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Changelog

Changelog
VersionDescription
1.0.0Introduced.

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