getPDO(); $pdo->exec(' CREATE TABLE tags2 ( id INTEGER PRIMARY KEY NOT NULL, name TEXT UNIQUE NOT NULL, usages INTEGER NOT NULL DEFAULT 0 )'); $pdo->exec('INSERT INTO tags2(name, usages) SELECT name, (SELECT COUNT(1) FROM postTags WHERE tagName = tags.name) FROM tags'); $pdo->exec('DROP TABLE tags'); $pdo->exec('ALTER TABLE tags2 RENAME TO tags'); $pdo->exec(' CREATE TABLE postTags2 ( postId INTEGER NOT NULL, tagId INTEGER NOT NULL, PRIMARY KEY (postId, tagId) )'); $pdo->exec('INSERT INTO postTags2(postId, tagId) SELECT postId, (SELECT tags.id FROM tags WHERE tags.name = postTags.tagName) FROM postTags'); $pdo->exec('DROP TABLE postTags'); $pdo->exec('ALTER TABLE postTags2 RENAME TO postTags'); } }