SQL_Translations::on_update_to_merge() can be confused by SQL inside text fields

[rmc47]

When SQL_Translations::on_update_to_merge() is called, we've already re-inserted the quoted string values that had been stripped out before other translations had taken place.

This means that the regexps in on_update_to_merge() can be confused by SQL-like syntax inside these string values. For example:

    $wpdb->query("INSERT INTO [wp_posts] ([post_author], [post_date], [post_date_gmt], [post_content], [post_content_filtered], [post_title], [post_excerpt], [post_status], [post_type], [comment_status], [ping_status], [post_password], [post_name], [to_ping], [pinged], [post_modified], [post_modified_gmt], [post_parent], [menu_order], [post_mime_type], [guid]) VALUES (1, '2019-02-27 23:23:12', '0000-00-00 00:00:00', 'Test content', '', 'Test', 'INSERT ... ON DUPLICATE KEY UPDATE', 'draft', 'ssc_blog_post', 'closed', 'closed', '', '', '', '', '2019-02-27 23:23:12', '0001-01-01 00:00:00', 0, 0, '', '')");

This will cause a SQL error on its first pass as a completely unrelated result of the invalid date, resulting in it hitting the translation routine.

Having done so though, the result of translation is quite spectacular 😄:

2019-02-27 23:37:19 Error Code: 241 -- Begin Query translation attempt:
INSERT INTO [wp_posts] ([post_author], [post_date], [post_date_gmt], [post_content], [post_content_filtered], [post_title], [post_excerpt], [post_status], [post_type], [comment_status], [ping_status], [post_password], [post_name], [to_ping], [pinged], [post_modified], [post_modified_gmt], [post_parent], [menu_order], [post_mime_type], [guid]) VALUES (1, '2019-02-27 23:23:12', '0000-00-00 00:00:00', 'Test content', '', 'Test', 'INSERT ... ON DUPLICATE KEY UPDATE', 'draft', 'ssc_blog_post', 'closed', 'closed', '', '', '', '', '2019-02-27 23:23:12', '0001-01-01 00:00:00', 0, 0, '', '')
2019-02-27 23:37:19 -- Translation result:
MERGE INTO  [wp_posts]  WITH (HOLDLOCK) AS target USING (SELECT 1 as [post_author],'2019-02-27 23:23:12' as [post_date],'0001-01-01 00:00:00' as [post_date_gmt],'Test content' as [post_content],'' as [post_content_filtered],'Test' as [post_title],'INSERT ... ON DUPLICATE KEY UPDATE' as [post_excerpt],'draft' as [post_status],'ssc_blog_post' as [post_type],'closed' as [comment_status],'closed' as [ping_status],'' as [post_password],'' as [post_name],'' as [to_ping],'' as [pinged],'2019-02-27 23:23:12' as [post_modified],'0001-01-01 00:00:00' as [post_modified_gmt],0 as [post_parent],0 as [menu_order],'' as [post_mime_type],'' as [guid]) AS source ([post_author], [post_date], [post_date_gmt], [post_content], [post_content_filtered], [post_title], [post_excerpt], [post_status], [post_type], [comment_status], [ping_status], [post_password], [post_name], [to_ping], [pinged], [post_modified], [post_modified_gmt], [post_parent], [menu_order], [post_mime_type], [guid]) ON (source.[post_author]=target.[post_author] AND source.[post_date]=target.[post_date] AND source.[post_date_gmt]=target.[post_date_gmt] AND source.[post_content]=target.[post_content] AND source.[post_content_filtered]=target.[post_content_filtered] AND source.[post_title]=target.[post_title] AND source.[post_excerpt]=target.[post_excerpt] AND source.[post_status]=target.[post_status] AND source.[post_type]=target.[post_type] AND source.[comment_status]=target.[comment_status] AND source.[ping_status]=target.[ping_status] AND source.[post_password]=target.[post_password] AND source.[post_name]=target.[post_name] AND source.[to_ping]=target.[to_ping] AND source.[pinged]=target.[pinged] AND source.[post_modified]=target.[post_modified] AND source.[post_modified_gmt]=target.[post_modified_gmt] AND source.[post_parent]=target.[post_parent] AND source.[menu_order]=target.[menu_order] AND source.[post_mime_type]=target.[post_mime_type] AND source.[guid]=target.[guid]) WHEN NOT MATCHED THEN INSERT ([post_author], [post_date], [post_date_gmt], [post_content], [post_content_filtered], [post_title], [post_excerpt], [post_status], [post_type], [comment_status], [ping_status], [post_password], [post_name], [to_ping], [pinged], [post_modified], [post_modified_gmt], [post_parent], [menu_order], [post_mime_type], [guid]) VALUES(1, '2019-02-27 23:23:12', '0001-01-01 00:00:00', 'Test content', '', 'Test', 'INSERT ... ON DUPLICATE KEY UPDATE', 'draft', 'ssc_blog_post', 'closed', 'closed', '', '', '', '', '2019-02-27 23:23:12', '0001-01-01 00:00:00', 0, 0, '', '');

Is there a reason why on_update_to_merge translation needs to be called after the preg_data is re-inserted into the query, or could it just be moved up a little earlier? (Doing so seems to do the right thing, but I'm not sure if the current position was deliberate.)