There is no need in DeleteUnusedCategories() so let's get rid of it.

pkg/mindflow/database/sqlite/db.go

@@ -22,8 +22,6 @@ var (
 	queryCategoryEdit string
 	//go:embed queries/categoryDelete.sql
 	queryCategoryDelete string
-	//go:embed queries/categoryDeleteUnused.sql
-	queryCategoryDeleteUnused string
 	//go:embed queries/postGetAll.sql
 	queryPostGetAll string
 	//go:embed queries/postNew.sql
@@ -39,7 +37,6 @@ var (
 	stmtCategoryNew    *sql.Stmt
 	stmtCategoryEdit   *sql.Stmt
 	stmtCategoryDelete *sql.Stmt
-	stmtCategoryDeleteUnused *sql.Stmt
 	stmtPostGetAll     *sql.Stmt
 	stmtPostNew        *sql.Stmt
 	stmtPostEdit       *sql.Stmt
@@ -74,11 +71,6 @@ func initDBStatements(db *sql.DB) error {
 		return errors.Wrap(err, "failed to prepare queryCategoryDelete")
 	}
 
-	stmtCategoryDeleteUnused, err = db.Prepare(queryCategoryDeleteUnused)
-	if err != nil {
-		return errors.Wrap(err, "failed to prepare queryCategoryDeleteUnused")
-	}
-
 	stmtPostGetAll, err = db.Prepare(queryPostGetAll)
 	if err != nil {
 		return errors.Wrap(err, "failed to prepare queryPostGetAll")
@@ -292,22 +284,6 @@ func (s *SQLiteMindflow) DeleteCategory(id int64) (err error) {
 	return nil
 }
 
-func (s *SQLiteMindflow) DeleteUnusedCategories() (err error) {
-	tx, err := s.db.Begin()
-	if err != nil {
-		return err
-	}
-	defer tx.Rollback()
-
-	if _, err = tx.Stmt(stmtCategoryDeleteUnused).Exec(); err != nil {
-		return err
-	}
-
-	tx.Commit()
-
-	return nil
-}
-
 func (s *SQLiteMindflow) Close() error {
 	stmtCategoryGetAll.Close()
 	stmtCategoryNew.Close()

pkg/mindflow/database/sqlite/queries/categoryDeleteUnused.sql

@@ -1,6 +0,0 @@
-DELETE FROM `category`
- WHERE `category`.`category_id` NOT IN (
-    SELECT `category_id`
-      FROM `post`
-     GROUP BY `post`.`category_id`
-    HAVING COUNT(`post`.`post_id`) > 0 );

pkg/mindflow/mindflow.go

@@ -52,7 +52,6 @@ type Mindflow interface {
 	NewCategory(category *Category) (int64, error)
 	EditCategory(category *Category) error
 	DeleteCategory(id int64) error
-	DeleteUnusedCategories() error
 	Categories() ([]Category, error)
 	Close() error
 }