2.20 Y,YYY 返回有逗号分隔显示的年 SQL> select to_char(SYSTIMESTAMP,'Y,YYY') from dual; TO_CHAR(SYSTIMESTAMP,'Y,YYY') ----------------------------- 2,015 2.21 Y/YY/YYY/YYYY 以指定长度返回日期的年份 SQL> select to_char(sysdate,'Y') from dual; TO_CHAR(SYSDATE,'Y') -------------------- 5 SQL> select to_char(sysdate,'YY') from dual; TO_CHAR(SYSDATE,'YY') --------------------- 15 SQL> select to_char(sysdate,'YYY') from dual; TO_CHAR(SYSDATE,'YYY') ---------------------- 015 SQL> select to_char(sysdate,'YYYY') from dual; TO_CHAR(SYSDATE,'YYYY') ----------------------- 2015 2.22 W 返回指定日期在当月中的第X周(范围:1-5) SQL> select to_char