Source

File: wp-admin/install-helper.php

function check_column( $table_name, $col_name, $col_type, $is_null = null, $key = null, $default = 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 ) && ( $row->Default !== $default ) ) {
				++$diffs;
			}
			if ( ( null !== $extra ) && ( $row->Extra !== $extra ) ) {
				++$diffs;
			}

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

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

	return false;
}