Manual:Category table/ja

Track all existing categories. Something is a category if
 * 1) it has an entry somewhere in categorylinks, or
 * 2) it once did.

Categories might not have corresponding pages, so they need to be tracked separately. ,, and   are signed to make underflow more obvious.

cat_id
主キー

cat_title
Name of the category, in the same form as page.page_title (with underscores). If there is a category page corresponding to this category, by definition, it has this name (in the Category namespace).

cat_pages
カテゴリに入っているページの数. この数字には、サブカテゴリの数やファイルの数を含みます.

cat_subcats
カテゴリに入っているサブカテゴリの数.

cat_files
カテゴリに入っているファイルの数.

cat_hidden
Was reserved for future use; apparently no one found a use for it because it was removed in v1.20. Instead, the status of hidden categories is stored in the page props table as the property "hiddencat" in.

スキーマの要約
DESCRIBE category; +-+-+--+-+-++ +-+-+--+-+-++ +-+-+--+-+-++
 * Field      | Type                | Null | Key | Default | Extra          |
 * cat_id     | int(10) unsigned    | NO   | PRI | NULL    | auto_increment |
 * cat_title  | varbinary(255)      | NO   | UNI | NULL    |                |
 * cat_pages  | int(11)             | NO   | MUL | 0       |                |
 * cat_subcats | int(11)            | NO   |     | 0       |                |
 * cat_files  | int(11)             | NO   |     | 0       |                |

DESCRIBE category; +-+-+--+-+-++ | Field      | Type                | Null | Key | Default | Extra          | +-+-+--+-+-++ | cat_id     | int(10) unsigned    | NO   | PRI | NULL    | auto_increment | | cat_title  | varbinary(255)      | NO   | UNI | NULL    |                | | cat_pages  | int(11)             | NO   | MUL | 0       |                | | cat_subcats | int(11)            | NO   |     | 0       |                | | cat_files  | int(11)             | NO   |     | 0       |                | | cat_hidden | tinyint(3) unsigned | NO   |     | 0       |                | +-+-+--+-+-++