wp_term_taxonomy

Last updated: February 12, 2026

Links terms to their taxonomies and stores taxonomy-specific data. Each term can appear in multiple taxonomies.

Schema

Column	Type	Null	Default	Description
`term_taxonomy_id`	bigint(20) unsigned	NO	auto_increment	Unique identifier
`term_id`	bigint(20) unsigned	NO	0	Term ID (FK → wp_terms.term_id)
`taxonomy`	varchar(32)	NO	”	Taxonomy name (category, post_tag, etc.)
`description`	longtext	NO	NULL	Term description
`parent`	bigint(20) unsigned	NO	0	Parent term_taxonomy_id (for hierarchical)
`count`	bigint(20)	NO	0	Cached count of associated objects

Indexes

Key Name	Columns	Unique	Purpose
`PRIMARY`	term_taxonomy_id	Yes	Primary key
`term_id_taxonomy`	term_id, taxonomy	Yes	Unique constraint
`taxonomy`	taxonomy	No	Filter by taxonomy

Foreign Key Relationships

term_id → wp_terms.term_id
parent → wp_term_taxonomy.term_taxonomy_id (self-referential)

Referenced by:

wp_term_relationships.term_taxonomy_id → wp_term_taxonomy.term_taxonomy_id

Built-in Taxonomies

Taxonomy	Description	Hierarchical
`category`	Post categories	Yes
`post_tag`	Post tags	No
`nav_menu`	Navigation menus	No
`link_category`	Link categories (legacy)	No
`post_format`	Post formats	No

Custom taxonomies are registered via register_taxonomy().

Common Queries

Get all terms for a taxonomy

SELECT t.*, tt.description, tt.count 
FROM wp_terms t
JOIN wp_term_taxonomy tt ON t.term_id = tt.term_id
WHERE tt.taxonomy = 'category'
ORDER BY t.name;

Get taxonomy counts

SELECT taxonomy, COUNT(*) as term_count 
FROM wp_term_taxonomy 
GROUP BY taxonomy 
ORDER BY term_count DESC;

Get hierarchical terms (categories with parents)

SELECT t.name, t.slug, tt.term_taxonomy_id, 
       tt.parent, p.name as parent_name
FROM wp_terms t
JOIN wp_term_taxonomy tt ON t.term_id = tt.term_id
LEFT JOIN wp_term_taxonomy ptt ON tt.parent = ptt.term_taxonomy_id
LEFT JOIN wp_terms p ON ptt.term_id = p.term_id
WHERE tt.taxonomy = 'category'
ORDER BY tt.parent, t.name;

Get term with post count

SELECT t.name, t.slug, tt.count
FROM wp_terms t
JOIN wp_term_taxonomy tt ON t.term_id = tt.term_id
WHERE tt.taxonomy = 'post_tag'
  AND tt.count > 0
ORDER BY tt.count DESC
LIMIT 20;

Get child terms

SELECT t.*, tt.term_taxonomy_id
FROM wp_terms t
JOIN wp_term_taxonomy tt ON t.term_id = tt.term_id
WHERE tt.parent = 5
  AND tt.taxonomy = 'category';

Get full term path (breadcrumb)

-- Recursive CTE for term ancestry
WITH RECURSIVE term_path AS (
  SELECT tt.term_taxonomy_id, tt.parent, t.name, t.slug, 1 as depth
  FROM wp_term_taxonomy tt
  JOIN wp_terms t ON tt.term_id = t.term_id
  WHERE tt.term_taxonomy_id = 10
  
  UNION ALL
  
  SELECT ptt.term_taxonomy_id, ptt.parent, pt.name, pt.slug, tp.depth + 1
  FROM term_path tp
  JOIN wp_term_taxonomy ptt ON tp.parent = ptt.term_taxonomy_id
  JOIN wp_terms pt ON ptt.term_id = pt.term_id
)
SELECT * FROM term_path ORDER BY depth DESC;

Count Maintenance

The count column is a cached value. WordPress updates it when:

Posts are added/removed from terms
Posts change status (publish/unpublish)

To manually recount:

wp_update_term_count( $term_taxonomy_ids, $taxonomy );

Or via SQL:

UPDATE wp_term_taxonomy tt
SET count = (
  SELECT COUNT(*) 
  FROM wp_term_relationships tr
  JOIN wp_posts p ON tr.object_id = p.ID
  WHERE tr.term_taxonomy_id = tt.term_taxonomy_id
    AND p.post_status = 'publish'
    AND p.post_type IN ('post', 'page')
)
WHERE tt.taxonomy = 'category';

WordPress API Functions

get_term( $term, $taxonomy ) – Returns term with taxonomy data
get_term_children( $term_id, $taxonomy ) – Get child term IDs
get_ancestors( $term_id, $taxonomy ) – Get ancestor term IDs
wp_count_terms( $taxonomy ) – Count terms in taxonomy