CREATE TABLE Catalog_Contents_Additional_Attributes (catalog_entry_id NUMBER, catalog_level_number NUMBER, attribute_id NUMBER, attribute_value VARCHAR2)
CREATE TABLE Catalog_Structure (catalog_level_number NUMBER, catalog_id NUMBER, catalog_level_name VARCHAR2)
CREATE TABLE Catalogs (catalog_id NUMBER, catalog_name VARCHAR2, catalog_publisher VARCHAR2, date_of_publication DATETIME, date_of_latest_revision DATETIME)
CREATE TABLE Catalog_Contents (catalog_entry_id NUMBER, catalog_level_number NUMBER, parent_entry_id NUMBER, previous_entry_id NUMBER, next_entry_id NUMBER, catalog_entry_name VARCHAR2, product_stock_number VARCHAR2, price_in_dollars DOUBLE PRECISION, price_in_euros DOUBLE PRECISION, price_in_pounds DOUBLE PRECISION, capacity VARCHAR2, length VARCHAR2, height VARCHAR2, width VARCHAR2)
CREATE TABLE Attribute_Definitions (attribute_id NUMBER, attribute_name VARCHAR2, attribute_data_type VARCHAR2)

Find the number of the names of catalog entries with level number 8.
SELECT catalog_entry_name, COUNT(catalog_entry_name) FROM Catalog_Contents AS t1 JOIN Catalog_Contents_Additional_Attributes AS t2 ON t1.catalog_entry_id = t2.catalog_entry_id WHERE t2.catalog_level_number = "8" GROUP BY catalog_entry_name
SELECT "catalog_entry_name", COUNT("catalog_entry_name") FROM "Catalog_Contents" "t1" JOIN "Catalog_Contents_Additional_Attributes" "t2" ON "8" = "t2"."catalog_level_number" AND "t1"."catalog_entry_id" = "t2"."catalog_entry_id" GROUP BY "catalog_entry_name"