1
SELECT a.runoob_id, a.runoob_author, b.runoob_count
FROM runoob_tbl a INNER JOIN tcount_tbl b ON a.runoob_author = b.runoob_author;
2
SELECT a.runoob_id, a.runoob_author, b.runoob_count
FROM runoob_tbl a, tcount_tbl b
WHERE a.runoob_author = b.runoob_author;
3.以上两个语句等价