Oracle のテーブルの総数をクエリする方法

SELECT COUNT(1) FROM USER_TABLES;

SELECT COUNT(1)
  FROM USER_COL_COMMENTS C
 WHERE EXISTS
 (SELECT 1 FROM USER_TABLES T WHERE T.TABLE_NAME = C.TABLE_NAME);

SELECT T.TABLE_NAME, T.NUM_ROWS, T.BLOCKS, T.EMPTY_BLOCKS
  FROM USER_TABLES T;

SELECT TABLE_NAME, TABLE_TYPE, COMMENTS
  FROM USER_TAB_COMMENTS
 WHERE COMMENTS LIKE '%字典%'

analyze table T_DATA compute statistics;
 
SELECT NUM_ROWS , AVG_ROW_LEN
  FROM USER_TABLES
 WHERE TABLE_NAME = 'T_DATA';
 
SELECT SEGMENT_NAME, SUM(BYTES) / 1024 / 1024
  FROM USER_EXTENTS
 GROUP BY SEGMENT_NAME;