Use of substr () in Oracle and InStr method in Oracle

in Oracle/plsql, the substrFunctions allows to extract a substring from a string.

The syntax for the substrfunction is:

substr(String, start_position, [length])
Description
The string is the source string.
Start_position is the position for extraction. The position inThe string is always 1.
The length is optional. It is the number of characters to extract. If This parameter is omitted, substrWould return the entire string.
For example:
substr(' This is a test ', 6, 2) would return ' is '
substr(' is a test ', 6) would return ' is a test '
substr(' Techonthenet ', 1, 4) would return ' Tech '
substr(' Techonthenet ', -3, 3) would return ' Net '
substr(' Techonthenet ',-6, 3) would return ' the '
substr(' Techonthenet ',-8, 2) would return ' on '



INSTRMethod is formatted as
INSTR(Source string, target string, starting position, matching ordinal number)

For example: INSTR(' CORPORATE FLOOR ', ' or ', 3, 2), the source string is ' CORPORATE FLOOR ', the target string is ' OR ', the starting position is 3, and the position of the 2nd match is taken.

The default lookup order is left to right. When the starting position is a negative number, start looking from the right.

So select INSTR(' CORPORATE FLOOR ', ' OR ',-1, 1) The display result of the "instring" from dual is

Instring