Converting Values 

For different application cases, you may need to change how values are represented because the operator used can deal only with a specific representation of values.

Prerequisites

You require the demo data for the SQL Tutorial.

Start the query tool SQL Studio as database administrator MONA with password RED and log on to the demo database instance DEMODB.

The SQL Reference Manual describes the following functions for these purposes: CHR(a,n), NUM(a), UPPER/LOWER(x), ASCII(x), MAPCHAR(x,n,i), ALPHA(x,n), HEX(a), CHAR(a,t), SOUNDEX(x), VALUE(x,y,...), DECODE(x,y(i),...,z)

Examples

SELECT * FROM hotel.hotel
  WHERE CHR(hno) LIKE '1__'

Displaying the hotel entries whose numbers contain three digits and begin with 1. The hotel number is converted to character values for this purpose.

Result

HNO	NAME	ZIP	ADDRESS
100	Beach	32018	1980 34th St.
110	Atlantic	33441	111 78th St.
120	Long Beach	90804	35 Broadway
130	Star	90029	13 Beechwood Place
140	River Boat	70112	788 MAIN STREET
150	Indian Horse	92262	16 MAIN STREET

 

See also:

SQL Reference Manual, CHR(a,n)

 

SELECT * FROM hotel.hotel
WHERE UPPER(name) = 'STAR'

Displaying the hotel name (case insensitive)

Result

HNO	NAME	ZIP	ADDRESS
130	Star	90029	13 Beechwood Place

 

See also:

SQL Reference Manual, UPPER/LOWER(x)

 

SELECT VALUE(firstname, 'Company') firstname, name
  FROM hotel.customer
    WHERE firstname IS NULL

Displaying the company name; the NULL value is to be replaced by the name Company

Result

FIRSTNAME	NAME
Company	Datasoft
Company	Toolware

 

See also:

SQL Reference Manual, VALUE(x,y,...)

 

SELECT hno, price, DECODE(type, 'single', 1, 'double', 2, 'suite', 3) code
  FROM hotel.room
    WHERE hno < 60

Displaying the hotel rooms with another name for the room types

Result

HNO	PRICE	CODE
10	200	2
10	135	1
20	100	2
20	70	1
30	80	2
30	45	1
40	140	2
40	85	1
50	180	2
50	105	1
50	500	3

See also:

SQL Reference Manual, DECODE(x,y(i),...,z)

More examples for Data Query