Select from a Subquery : Select clause « Query Select « Oracle PL/SQL Tutorial






  1. Oracle PL/SQL Tutorial
  2. Query Select
  3. Select clause
SQL>
SQL>
SQL>
SQL> create table history
  2  ( empno      NUMBER(4)
  3  , beginyear  NUMBER(4)
  4  , begindate  DATE
  5  , enddate    DATE
  6  , deptno     NUMBER(2)
  7  , msal       NUMBER(6,2)
  8  , comments   VARCHAR2(60)
  9  ) ;

Table created.

SQL>
SQL>
SQL>
SQL> insert into history values (9,2000,date '2000-01-01',date '2002-01-02',40, 950,'history for 9');

1 row created.

SQL> insert into history values (8,2000,date '2000-01-02', NULL       ,20, 800,'');

1 row created.

SQL> insert into history values (7,1988,date '2000-01-06',date '2002-01-07',30,1000,'');

1 row created.

SQL> insert into history values (6,1989,date '2000-01-07',date '2002-01-12',30,1300,'');

1 row created.

SQL> insert into history values (5,1993,date '2000-01-12',date '2002-01-10',30,1500,'history for 5');

1 row created.

SQL> insert into history values (4,1995,date '2000-01-10',date '2002-01-11',30,1700,'');

1 row created.

SQL> insert into history values (3,1999,date '2000-01-11', NULL       ,30,1600,'');

1 row created.

SQL> insert into history values (2,1986,date '2000-01-10',date '2002-01-08',20,1000,'history for 2');

1 row created.

SQL> insert into history values (1,1987,date '2000-01-08',date '2002-01-01',30,1000,'history for 1');

1 row created.

SQL> insert into history values (7,1989,date '2000-01-01',date '2002-05-12',30,1150,'history for 7');

1 row created.

SQL>
SQL>
SQL>
SQL> select *
  2  from  (select empno, msal
  3         from   history
  4         order  by msal desc)
  5  where  rownum <= 3;

 EMPNO   MSAL
------ ------
     4   1700
     3   1600
     5   1500

3 rows selected.

SQL>
SQL> drop table history;

Table dropped.

SQL>
SQL>








2.2.Select clause
2.2.1.Performing Single Table SELECT Statements
2.2.2.Select employee first and last and sort by last name
2.2.3.List single column from a table
2.2.4.Use as to specify the alias name
2.2.5.Use function in select clause
2.2.6.Use more than one aggregate functions in a select statement
2.2.7.where clause
2.2.8.Compare with number
2.2.9.Concatenate string
2.2.10.Select from a Subquery
2.2.11.Select constant as a column
2.2.12.Negate a column value
2.2.13.Math calculation in select statement
2.2.14.Search for String Across Columns
2.2.15.Don't Perform the Same Calculation Over and Over
2.2.16.NO_INDEX function in select statement