OVERLAYB

Returns an octet value representing a string having had a substring replaced by another string.

Behavior Type

Immutable

Syntax

OVERLAYB ( expression1, expression2, position [ , extent ] )

Parameters

expression1 

(CHAR or VARCHAR) is the string to process

expression2 

(CHAR or VARCHAR) is the substring to overlay

position 

(INTEGER) is the octet position (counting from one) at which to begin the overlay

extent 

(INTEGER) specifies the number of octets to replace with the overlay

Notes

The OVERLAYB function treats the multibyte character string as a string of octets (bytes) and use octet numbers as incoming and outgoing position specifiers and lengths. The strings themselves are type VARCHAR, but they treated as if each byte was a separate character.

Examples

=> SELECT OVERLAYB('123456789', 'ééé', 2);
 OVERLAYB
----------
 1ééé89
(1 row)
=> SELECT OVERLAYB('123456789', 'ßßß', 2);
 OVERLAYB
----------
 1ßßß89
(1 row)
=> SELECT OVERLAYB('123456789', 'xxx', 2);
 OVERLAYB
-----------
 1xxx56789
(1 row)
=> SELECT OVERLAYB('123456789', 'xxx', 2, 4);
 OVERLAYB
----------
 1xxx6789
(1 row)
=> SELECT OVERLAYB('123456789', 'xxx', 2, 5);
 OVERLAYB
----------
 1xxx789
(1 row)
=> SELECT OVERLAYB('123456789', 'xxx', 2, 6);
 OVERLAYB
----------
 1xxx89
(1 row)