Oracle SQL - Select SELECT Clause

Introduction

Issuing a Simple SELECT Command

select * from departments; 
  

The asterisk (*) symbol is used to specify that you would like all columns of the DEPARTMENTS table to be displayed in the column listing.

The following code shows a query that selects specific columns from the EMPLOYEES table and uses a WHERE clause to specify a condition for the rows retrieved.

select ename, init, job, msal 
from   emp 
where  deptno = 30; 
  

In the SELECT clause, white space is mandatory after the keyword SELECT.

The columns or column expressions are separated by commas; therefore, white space is not mandatory.

White space is mandatory after the keywords FROM and WHERE.

Demo

SQL>
SQL> drop table emp;

Table dropped.--   www  . ja  v a 2 s.co m

SQL> create table emp(
  2  empno      NUMBER(4)    primary key,
  3  ename      VARCHAR2(8)  not null   ,
  4  init       VARCHAR2(5)  not null   ,
  5  job        VARCHAR2(8)             ,
  6  mgr        NUMBER(4)               ,
  7  bdate      DATE         not null   ,
  8  msal       NUMBER(6,2)  not null   ,
  9  comm       NUMBER(6,2)             ,
 10  deptno     NUMBER(2)    default 10) ;
SQL>
SQL> insert into emp values(7001,'SMITH','N',  'TRAINER', 7902,date '1975-12-17',  1800 , NULL, 20);
SQL> insert into emp values(7002,'ALLEN','JAM','SALESREP',7006,date '1971-05-20',  1600, 300,   30);
SQL> insert into emp values(7003,'WARD', 'TF' ,'SALESREP',7006,date '1972-03-02',  1250, 500,   10);
SQL> insert into emp values(7004,'JACK', 'JM', 'MANAGER', 7009,date '1977-04-02',  2975, NULL,  20);
SQL> insert into emp values(7005,'BROWN','P',  'SALESREP',7006,date '1976-09-28',  1250, 1400,  30);
SQL> insert into emp values(7006,'BLAKE','R',  'MANAGER', 7009,date '1973-11-01',  2850, NULL,  10);
SQL> insert into emp values(7007,'CLARK','AB', 'MANAGER', 7009,date '1975-06-09',  2450, NULL,  10);
SQL> insert into emp values(7008,'SCOTT','DEF','TRAINER', 7004,date '1979-11-26',  3000, NULL,  20);
SQL> insert into emp values(7009,'KING', 'CC', 'DIRECTOR',NULL,date '1972-10-17',  5000, NULL,  10);
SQL> insert into emp values(7010,'BREAD','JJ', 'SALESREP',7006,date '1978-09-28',  1500, 0,     30);
SQL> insert into emp values(7011,'ADAMS','AA', 'TRAINER', 7008,date '1976-12-30',  1100, NULL,  20);
SQL> insert into emp values(7012,'JONES','R',  'ADMIN',   7006,date '1979-10-03',  8000, NULL,  30);
SQL> insert into emp values(7902,'FORD', 'MG', 'TRAINER', 7004,date '1979-02-13',  3000, NULL,  20);
SQL> insert into emp values(7934,'MARY', 'ABC','ADMIN',   7007,date '1972-01-23',  1300, NULL,  10);
SQL> select * from departments;

   DEPTNO | DNAME      | LOCATION |       MGR
--------- | ---------- | -------- | ---------
    1     | ACCOUNTING | NEW YORK |  07007.00
    2     | TRAINING   | DALLAS   |  07004.00
    30    | SALES      | CHICAGO  |  07006.00
    4     | HR         | BOSTON   |  07009.00

SQL>
SQL> select ename, init, job, msal
  2  from   emp
  3  where  deptno = 30;

ENAME    | INIT  | JOB      |      MSAL
-------- | ----- | -------- | ---------
ALLEN    | JAM   | SALESREP |  01600.00
BROWN    | P     | SALESREP |  01250.00
BREAD    | JJ    | SALESREP |  01500.00
JONES    | R     | ADMIN    |  08000.00

SQL>

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