一个电源问题招成的困惑

COLUMN命令： --控制列的格式
选项：CLE[AR] --清楚列的格式
HEA[DING] text no --设置列标题
FOR[MAT] format --使用格式样式更改列的显示
NOPRINT | PRINT --隐藏列|显示列
NULL text --指定的值为空时显示的文本
格式样式：



例：COLUMN last_name HEADING 'Employee|Name'
COLUMN salary JUSTIFY LEFT FORMAT $99,990.00
COLUMN manager FORMAT 999999999 NULL 'No manager'
COLUMN last_name CLEAR --清除last_name列的设置

BREAK命令： --取消重复的项
BREAK ON job_id

TTITLE | BTITLE命令：
TTITLE | BTITLE [text|OFF|ON] --显示页眉页脚
TTITLE 'Salary|Report' --设置报表页眉
BTITLE 'Confidential' --设置报表页脚

报表实例模版：
例1：SET FEEDBACK OFF
TTITLE 'Employee|Report'
BTITLE 'Confidential'
BREAK ON job_id
COLUMN job_id HEADING 'Job|Category'
COLUMN last_name HEADING 'Employee'
COLUMN salary HEADING 'Salary' FORMAT $99,999.99
REM ** Insert SELECT statement
SELECT job_id, last_name, salary
FROM employees
WHERE salary < 15000
ORDER BY job_id, last_name
/
REM clear all formatting commands ...
SET FEEDBACK ON

TTITLE OFF
BTITLE OFF

COLUMN last_name CLEAR
COLUMN salary CLEAR
CLEAR BREAK

例2：BREAK ON DEPARTMENT_ID ON JOB_ID DUPLICATES
COMPUTE SUM OF SALARY ON DEPARTMENT_ID
COMPUTE AVG OF SALARY ON JOB_ID
SELECT DEPARTMENT_ID, JOB_ID, LAST_NAME, SALARY FROM employees
WHERE JOB_ID IN ('SH_CLERK', 'SA_MAN') AND DEPARTMENT_ID IN (50, 80)
ORDER BY DEPARTMENT_ID, JOB_ID;

REPHEADER PAGE CENTER "EMPLOYEE LISTING REPORT"
repfooter page right 'footer'
TTITLE RIGHT 'Page: ' FORMAT 999
SELECT LAST_NAME, SALARY FROM employees
where salary>12000；

SET FEEDBACK OFF
TTITLE 'Employee|Report'
BTITLE 'Confidential'
BREAK ON job_id
COLUMN job_id HEADING 'Job|Category'
COLUMN last_name HEADING 'Employee'
COLUMN salary HEADING 'Salary' FORMAT $99,999.99
REM ** Insert SELECT statement
SELECT job_id, last_name, salary
FROM employees
WHERE salary < 15000
ORDER BY job_id, last_name
/
REM clear all formatting commands ...
SET FEEDBACK ON
COLUMN job_id CLEAR
COLUMN last_name CLEAR
COLUMN salary CLEAR
CLEAR BREAK

COLUMN job_id CLEAR