PLS-01424：Non-ANSI order of clauses

错误原因：ANSI specifies an ordering to clauses in a table-expression which PL/SQL doesn't. The ordering according to ANSI must be: (1) from clause (2) where clause (3) group-by clause (4) having clause In PL/SQL, the from clause must come first, and the clauses after it can appear in any order (with the addition of the non-ansi connect-by clause).