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 can use the demo data for the SQL tutorial. Start the Database Studio as database administrator MONA with the password RED and log on to demo database DEMODB: Logging On to a Database.

The following functions are described for this purpose in the SQL reference manual: 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).

Activities

You can use Database Studio to enter and execute SQL statements. More information: Working with SQL Statements: Overview

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`	`Atlantik`	`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 (not case-sensitive)

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 Information

More examples for Data Query