কেন এটি প্রয়োজনীয় তা আমি পুরোপুরি বুঝতে পেরেছি - কমপক্ষে আমার পক্ষে দ্রুত প্রোটোটাইপিংয়ের সময় এটি কার্যকর যখন অনেকগুলি টেবিলের সাথে যোগ দেওয়ার দরকার হয়, যার মধ্যে অনেকগুলি অন্তর্ভুক্ত যোগদান করে। যত তাড়াতাড়ি একটি কলামের নাম দ্বিতীয় "জোড়ের টেবিল। *" ফিল্ড ওয়াইল্ড কার্ডে একই হয়, মূল টেবিলের ক্ষেত্রের মানগুলি জোড়যোগ্য টেবিলগুলির সাথে ওভার্রাইড করা হয়। প্রবণতা, হতাশার এবং DRY লঙ্ঘনের সময় ত্রুটিগুলি যখন বারে বারে এলিয়াসগুলির সাথে টেবিল ক্ষেত্রগুলি ম্যানুয়ালি নির্দিষ্ট করে থাকে ...
কোড জেনারেশনের মাধ্যমে এটি কীভাবে ব্যবহার করতে হয় তার উদাহরণ সহ এটি অর্জনের জন্য এখানে একটি পিএইচপি (ওয়ার্ডপ্রেস) ফাংশন রয়েছে। উদাহরণস্বরূপ, এটি দ্রুত একটি কাস্টম ক্যোয়ারী উত্পন্ন করতে ব্যবহৃত হয় যা সম্পর্কিত ওয়ার্ডপ্রেস পোস্টের ক্ষেত্রগুলি সরবরাহ করবে যা উন্নত কাস্টম ক্ষেত্র ক্ষেত্রের মাধ্যমে উল্লেখ করা হয়েছিল ।
function prefixed_table_fields_wildcard($table, $alias)
{
global $wpdb;
$columns = $wpdb->get_results("SHOW COLUMNS FROM $table", ARRAY_A);
$field_names = array();
foreach ($columns as $column)
{
$field_names[] = $column["Field"];
}
$prefixed = array();
foreach ($field_names as $field_name)
{
$prefixed[] = "`{$alias}`.`{$field_name}` AS `{$alias}.{$field_name}`";
}
return implode(", ", $prefixed);
}
function test_prefixed_table_fields_wildcard()
{
global $wpdb;
$query = "
SELECT
" . prefixed_table_fields_wildcard($wpdb->posts, 'campaigns') . ",
" . prefixed_table_fields_wildcard($wpdb->posts, 'venues') . "
FROM $wpdb->posts AS campaigns
LEFT JOIN $wpdb->postmeta meta1 ON (meta1.meta_key = 'venue' AND campaigns.ID = meta1.post_id)
LEFT JOIN $wpdb->posts venues ON (venues.post_status = 'publish' AND venues.post_type = 'venue' AND venues.ID = meta1.meta_value)
WHERE 1
AND campaigns.post_status = 'publish'
AND campaigns.post_type = 'campaign'
LIMIT 1
";
echo "<pre>$query</pre>";
$posts = $wpdb->get_results($query, OBJECT);
echo "<pre>";
print_r($posts);
echo "</pre>";
}
আউটপুট:
SELECT
`campaigns`.`ID` AS `campaigns.ID`, `campaigns`.`post_author` AS `campaigns.post_author`, `campaigns`.`post_date` AS `campaigns.post_date`, `campaigns`.`post_date_gmt` AS `campaigns.post_date_gmt`, `campaigns`.`post_content` AS `campaigns.post_content`, `campaigns`.`post_title` AS `campaigns.post_title`, `campaigns`.`post_excerpt` AS `campaigns.post_excerpt`, `campaigns`.`post_status` AS `campaigns.post_status`, `campaigns`.`comment_status` AS `campaigns.comment_status`, `campaigns`.`ping_status` AS `campaigns.ping_status`, `campaigns`.`post_password` AS `campaigns.post_password`, `campaigns`.`post_name` AS `campaigns.post_name`, `campaigns`.`to_ping` AS `campaigns.to_ping`, `campaigns`.`pinged` AS `campaigns.pinged`, `campaigns`.`post_modified` AS `campaigns.post_modified`, `campaigns`.`post_modified_gmt` AS `campaigns.post_modified_gmt`, `campaigns`.`post_content_filtered` AS `campaigns.post_content_filtered`, `campaigns`.`post_parent` AS `campaigns.post_parent`, `campaigns`.`guid` AS `campaigns.guid`, `campaigns`.`menu_order` AS `campaigns.menu_order`, `campaigns`.`post_type` AS `campaigns.post_type`, `campaigns`.`post_mime_type` AS `campaigns.post_mime_type`, `campaigns`.`comment_count` AS `campaigns.comment_count`,
`venues`.`ID` AS `venues.ID`, `venues`.`post_author` AS `venues.post_author`, `venues`.`post_date` AS `venues.post_date`, `venues`.`post_date_gmt` AS `venues.post_date_gmt`, `venues`.`post_content` AS `venues.post_content`, `venues`.`post_title` AS `venues.post_title`, `venues`.`post_excerpt` AS `venues.post_excerpt`, `venues`.`post_status` AS `venues.post_status`, `venues`.`comment_status` AS `venues.comment_status`, `venues`.`ping_status` AS `venues.ping_status`, `venues`.`post_password` AS `venues.post_password`, `venues`.`post_name` AS `venues.post_name`, `venues`.`to_ping` AS `venues.to_ping`, `venues`.`pinged` AS `venues.pinged`, `venues`.`post_modified` AS `venues.post_modified`, `venues`.`post_modified_gmt` AS `venues.post_modified_gmt`, `venues`.`post_content_filtered` AS `venues.post_content_filtered`, `venues`.`post_parent` AS `venues.post_parent`, `venues`.`guid` AS `venues.guid`, `venues`.`menu_order` AS `venues.menu_order`, `venues`.`post_type` AS `venues.post_type`, `venues`.`post_mime_type` AS `venues.post_mime_type`, `venues`.`comment_count` AS `venues.comment_count`
FROM wp_posts AS campaigns
LEFT JOIN wp_postmeta meta1 ON (meta1.meta_key = 'venue' AND campaigns.ID = meta1.post_id)
LEFT JOIN wp_posts venues ON (venues.post_status = 'publish' AND venues.post_type = 'venue' AND venues.ID = meta1.meta_value)
WHERE 1
AND campaigns.post_status = 'publish'
AND campaigns.post_type = 'campaign'
LIMIT 1
Array
(
[0] => stdClass Object
(
[campaigns.ID] => 33
[campaigns.post_author] => 2
[campaigns.post_date] => 2012-01-16 19:19:10
[campaigns.post_date_gmt] => 2012-01-16 19:19:10
[campaigns.post_content] => Lorem ipsum
[campaigns.post_title] => Lorem ipsum
[campaigns.post_excerpt] =>
[campaigns.post_status] => publish
[campaigns.comment_status] => closed
[campaigns.ping_status] => closed
[campaigns.post_password] =>
[campaigns.post_name] => lorem-ipsum
[campaigns.to_ping] =>
[campaigns.pinged] =>
[campaigns.post_modified] => 2012-01-16 21:01:55
[campaigns.post_modified_gmt] => 2012-01-16 21:01:55
[campaigns.post_content_filtered] =>
[campaigns.post_parent] => 0
[campaigns.guid] => http://example.com/?p=33
[campaigns.menu_order] => 0
[campaigns.post_type] => campaign
[campaigns.post_mime_type] =>
[campaigns.comment_count] => 0
[venues.ID] => 84
[venues.post_author] => 2
[venues.post_date] => 2012-01-16 20:12:05
[venues.post_date_gmt] => 2012-01-16 20:12:05
[venues.post_content] => Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.
[venues.post_title] => Lorem ipsum venue
[venues.post_excerpt] =>
[venues.post_status] => publish
[venues.comment_status] => closed
[venues.ping_status] => closed
[venues.post_password] =>
[venues.post_name] => lorem-ipsum-venue
[venues.to_ping] =>
[venues.pinged] =>
[venues.post_modified] => 2012-01-16 20:53:37
[venues.post_modified_gmt] => 2012-01-16 20:53:37
[venues.post_content_filtered] =>
[venues.post_parent] => 0
[venues.guid] => http://example.com/?p=84
[venues.menu_order] => 0
[venues.post_type] => venue
[venues.post_mime_type] =>
[venues.comment_count] => 0
)
)