第二章 SQL基础
1．略。
2．略。
3．
SQL> SET LINE 100
SQL> SET PAGESIZE 50
SQL> SELECT empno, ename, job, sal
FROM emp;
EMPNO ENAME JOB SAL
---------- ---------- ---------
----------
7369 SMITH CLERK 800
7499 ALLEN SALESMAN 1600
7521 WARD SALESMAN 1250
7566 JONES MANAGER 2975
7654 MARTIN SALESMAN 1250
7698 BLAKE MANAGER 2850
7782 CLARK MANAGER 2450
7788 SCOTT ANALYST 3000
7839 KING PRESIDENT 5000
7844 TURNER SALESMAN 1500
7876 ADAMS CLERK 1100
7900 JAMES CLERK 950
7902 FORD ANALYST 3000
7934 MILLER CLERK 1300
4．
SQL>
SELECT ename, sal, job FROM emp;
Employee
Name SAL JOB
---------------
----------- ----------
SMITH $800.00 CLERK
ALLEN $1,600.00 SALESMAN
WARD $1,250.00 SALESMAN
JONES $2,975.00 MANAGER
MARTIN $1,250.00 SALESMAN
BLAKE $2,850.00 MANAGER
CLARK $2,450.00 MANAGER
SCOTT $3,000.00 ANALYST
KING $5,000.00 PRESIDENT
TURNER $1,500.00 SALESMAN
ADAMS $1,100.00 CLERK
JAMES $950.00 CLERK
FORD $3,000.00 ANALYST
MILLER $1,300.00 CLERK
5．不正确，缓存中只能保存最后一条SQL语句。
6．不正确，查看表结构的命令DESC emp属于SQL*PLUS命令，而不是SQL命令，它们能访问数据库。
7．略。
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