Oracle存储过程获取YYYY-MM-DD的时间格式

环境：Oracle 10g,11g

问题重现：PL/SQL中命令窗口下，发现存储过程得到的时间格式不符合预期要求。

SQL> select sysdate from dual;
SYSDATE
-----------
2014-12-18
Executed in 0 seconds
SQL> set serveroutput on
SQL> declare
2 pro_date date;
3 begin
4 select sysdate into pro_date from dual;
5 dbms_output.put_line(pro_date);
6 end;
18-12月-14
PL/SQL procedure successfully completed
Executed in 0.016 seconds

处理方法1：将结果转换成字符串格式：

SQL> 
SQL> declare
2 pro_date date;
3 begin
4 select sysdate into pro_date from dual;
5 dbms_output.put_line(to_char(pro_date,'yyyy-mm-dd'));
6 end;
2014-12-18
PL/SQL procedure successfully completed
Executed in 0.016 seconds
SQL> declare
2 pro_date date;
3 begin
4 select sysdate into pro_date from dual;
5 dbms_output.put_line(pro_date);
6 end;
18-12月-14
PL/SQL procedure successfully completed
Executed in 0 seconds

处理方法2：改变会话的NLS_DATE_FORMAT

SQL> alter session set nls_date_format='yyyy-mm-dd hh24:mi:ss';
Session altered
Executed in 0.015 seconds
SQL> declare
2 pro_date date;
3 begin
4 select sysdate into pro_date from dual;
5 dbms_output.put_line(pro_date);
6 end;
2014-12-18 11:18:15
PL/SQL procedure successfully completed
Executed in 0 seconds
SQL> alter session set nls_date_format='yyyy-mm-dd';
Session altered
Executed in 0 seconds
SQL> declare
2 pro_date date;
3 begin
4 select sysdate into pro_date from dual;
5 dbms_output.put_line(pro_date);
6 end;
2014-12-18
PL/SQL procedure successfully completed
Executed in 0 seconds

总结： 在Oracle存储过程想要获取YYYY-MM-DD的时间格式，可以转换成字符串处理，可以临时指定会话的NLS_DATE_FORMAT变量，还可以整体修改客户端的环境变量。