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OVERLAY returns a VARCHAR value representing a string having had a substring replaced by another string.
Syntax
OVERLAY ( expression1 PLACING expression2 FROM position [ FOR extent ] )
Semantics
expression1 |
(CHAR or VARCHAR) is the string to process |
expression2 |
(CHAR or VARCHAR) is the substring to overlay |
position |
(INTEGER) is the character position (counting from one) at which to begin the overlay |
extent |
(INTEGER) specifies the number of characters to replace with the overlay |
Examples
=> \a
Output format is unaligned.
=> SELECT OVERLAY('123456789' PLACING 'xxx' FROM 2);
overlay
1xxx56789
(1 row)
=> SELECT OVERLAY('123456789' PLACING 'xxx' FROM 2 FOR 4);
overlay
1xxx6789
(1 row)
=> SELECT OVERLAY('123456789' PLACING 'xxx' FROM 2 FOR 5);
overlay
1xxx789
(1 row)
=> SELECT OVERLAY('123456789' PLACING 'xxx' FROM 2 FOR 6);
overlay
1xxx89
(1 row)