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本文作者系流浪的金鱼（花名），甲骨文数据库工程师。个人主页：https://blog.csdn.net/rishairu1，经其本人授权发布。

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有的时候，我们可能突然遇到在sqlplus上，以前执行很正常的sql语句，突然表示的格式发生了变化。并且发现这个sql语句中使用了To_char函数。

例如如下的这个表空间使用率的sql。

SQL> set lines 120set pages 100set term offtti offclear colcol TABLESPACE_NAME     format a15col "SIZE(MB)"          format a20col "USED(MB)"          format a20col "FREE(MB)"          format a20col "USED(%)"           format 990.99select  tablespace_name,  to_char(nvl(total_bytes / 1024,0),'999,999,999') as "size(MB)",  to_char(nvl((total_bytes - free_total_bytes) / 1024 / 1024,0),'999,999,999') as "used(MB)",  to_char(nvl(free_total_bytes / 1024 / 1024,0),'999,999,999') as "free(MB)",  round(nvl((total_bytes - free_total_bytes) / total_bytes * 100,100),2) as "rate(%)"from  ( select      tablespace_name,      sum(bytes) total_bytes    from      dba_data_files    group by      tablespace_name  ),  ( select      tablespace_name free_tablespace_name,      sum(bytes) free_total_bytes    from      dba_free_space    group by tablespace_name  )where  tablespace_name = free_tablespace_name(+)/

正常的时候是如下格式表示。

TABLESPACE_NAME size(MB)             used(MB)             free(MB)                rate(%)--------------- -------------------- -------------------- -------------------- ----------SYSAUX             7,809,024                7,084                  543              92.89UNDOTBS1           1,536,000                   44                1,456               2.96USERS              3,000,320                   11                2,919                .39SYSTEM             1,034,240                1,008                    2              99.76SCOTT_TBS             44,928                   32                   12              72.22

但是某一天突然变成了如下串行的格式。并且sql语句没有变过。也没有打什么补丁。

TABLESPACE_NAME ---------------------------------------------------------------size(MB)         -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------used(MB)          -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------free(MB)  -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------rate(%)---------------------------------------------------------------SYSAUX             7,809,024                7,084                  543              92.89

UNDOTBS1           1,536,000                  44                1,456               2.96 USERS              3,000,320                   11                2,919                .39

SYSTEM             1,034,240                1,008                    2              99.76

SCOTT_TBS             44,928                   32                   12              72.22