Shulou(Shulou.com)06/02 Report--

Basic query

SQL >-- current user

SQL > show use

USER is "SCOTT"

SQL >-- the table under the current user

SQL > select * from tab

TNAME TABTYPE CLUSTERID

DEPT TABLE

EMP TABLE

BONUS TABLE

SALGRADE TABLE

SQL >-- structure of the employee table

SQL > desc emp

Is the name empty? Types

EMPNO NOT NULL NUMBER (4)

ENAME VARCHAR2 (10)

JOB VARCHAR2 (9)

MGR NUMBER (4)

HIREDATE DATE

SAL NUMBER (7 dint 2)

COMM NUMBER (7 dint 2)

DEPTNO NUMBER (2)

SQL >-- clear the screen

SQL > host cls

SQL >-- query all employee information

SQL > select * from emp

EMPNO ENAME JOB MGR HIREDATE SAL COMMDEPTNO 7369 SMITH CLERK 7902 17-December-80 800 20 7499 ALLEN SALESMAN 7698 20-February-81 1600 300 30 7521 WARD SALESMAN 7698 22-February-81 1250 7698 30 EMPNO ENAME JOB MGR HIREDATE SAL COMMDEPTNO 7566 JONES MANAGER 7839 02-April-81 2975 20 7654 MARTIN SALESMAN 7698 28-September-81 1250 1400 30 7698 BLAKE MANAGER 7839 01-May-81 2850 30 EMPNO ENAME JOB MGR HIREDATE SAL COMMDEPTNO 7782 CLARK MANAGER 7839 09-June-81 2450 10 7788 SCOTT ANALYST 7566 19-April-87 3000 20 7839 KING PRESIDENT 17-November-81 5000 10 EMPNO ENAME JOB MGR HIREDATE SAL COMMDEPTNO 7844 TURNER SALESMAN 7698 08-September- 81 1500 0 30 7876 ADAMS CLERK 7788 23-May-87 1100 20 7900 JAMES CLERK 7698 03-December-81 950 30 EMPNO ENAME JOB MGR HIREDATE SAL COMMDEPTNO 7902 FORD ANALYST 7566 03-December-81 3000 20 7934 MILLER CLERK 7782 23-January-82 1300 10

14 rows have been selected.

SQL >-- set the line width

SQL > show linesize

Linesize 80

SQL > set linesize 120

SQL >-- set column width

SQL > col ename for A8

SQL > col sal for 9999

SQL > /

EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO 7369 SMITH CLERK 7902 17-December-80800 20 7499 ALLEN SALESMAN 7698 20-February-81 1600 300 30 7521 WARD SALESMAN 7698 22-February-81 1250 1250 30 7566 JONES MANAGER 7839 02-April-81 2975 20 7654 MARTIN SALESMAN 7698 28-September-81 1250 1400 30 7698 BLAKE MANAGER 7839 01-May-81 2850 30 7782 CLARK MANAGER 7839 09-June-81 2450 10 7788 SCOTT ANALYST 7566 19-April-87 3000 20 7839 KING PRESIDENT 17-November-81 5000 10 7844 TURNER SALESMAN 7698 08 -September-81 1500 0 30 7876 ADAMS CLERK 7788 23-May-87 1100 20 EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO 7900 JAMES CLERK 7698 03-December-81 950 30 7902 FORD ANALYST 7566 03-December-81 3000 20 7934 MILLER CLERK 7782 23-January -82 1300 10

14 rows have been selected.

SQL >-- by column name

SQL > select empno,ename,job,mgr,hiredate,sal,comm,deptno

2 from emp

EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO 7369 SMITH CLERK 7902 17-December-80800 20 7499 ALLEN SALESMAN 7698 20-February-81 1600 300 30 7521 WARD SALESMAN 7698 22-February-81 1250 1250 30 7566 JONES MANAGER 7839 02-April-81 2975 20 7654 MARTIN SALESMAN 7698 28-September-81 1250 1400 30 7698 BLAKE MANAGER 7839 01-May-81 2850 30 7782 CLARK MANAGER 7839 09-June-81 2450 10 7788 SCOTT ANALYST 7566 19-April-87 3000 20 7839 KING PRESIDENT 17-November-81 5000 10 7844 TURNER SALESMAN 7698 08 -September-81 1500 0 30 7876 ADAMS CLERK 7788 23-May-87 1100 20 EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO 7900 JAMES CLERK 7698 03-December-81 950 30 7902 FORD ANALYST 7566 03-December-81 3000 20 7934 MILLER CLERK 7782 23-January -82 1300 10

14 rows have been selected.

SQL > / *

Principles for SQL > SQL optimization:

SQL > 1. Use column names as much as possible

SQL > * /

SQL > host cls

SQL >-- query employee information: employee number, name, monthly salary

SQL > select empno,ename,sal

2 form emp

Form emp

*

An error occurred on line 2:

ORA-00923: no required FROM keyword found

SQL >-- c command change

SQL > 2

2 * form emp

SQL > c / form/from

2 * from emp

SQL > /

EMPNO ENAME SAL

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.