如果列尚不存在,则将列添加到数据库表。
原型
maybe_add_column( string $table_name, string $column_name, string $create_ddl )
参数
$table_name
(string)
(Required)
要修改的表名。
$column_name
(string)
(Required)
要添加到表中的列名称。
$create_ddl
(string)
(Required)
用于添加列的SQL语句。
返回值
(bool)
如果已存在或成功完成,则为True,错误时为false。
源文件
路径:wp-admin/includes/upgrade.php
<?php
...
function maybe_add_column($table_name, $column_name, $create_ddl) {
global $wpdb;
foreach ($wpdb->get_col("DESC $table_name", 0) as $column ) {
if ($column == $column_name) {
return true;
}
}
// Didn't find it try to create it.
$wpdb->query($create_ddl);
// We cannot directly tell that whether this succeeded!
foreach ($wpdb->get_col("DESC $table_name", 0) as $column ) {
if ($column == $column_name) {
return true;
}
}
return false;
}
...
?>
其他
英文文档:https://developer.wordpress.org/reference/functions/maybe_add_column/