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PREFIX function (extension)
Syntax
PREFIX(char_expression, start_position, char_expression)
Description
The scalar function PREFIX returns the substring of a character string starting from the position specified by start position, and ending before the specified character.
Arguments
char_expression
An expression that evaluates to a character string, typically a character-string literal or column name. If the expression evaluates to null, PREFIX returns null.
start_position
An expression that evaluates to an integer value. PREFIX searches the string specified in the first argument starting at that position. A value of one indicates the first character of the string.
char_expression
An expression that evaluates to a single character. PREFIX returns the substring that ends before that character. If PREFIX does not find the character, it returns the substring beginning with start_position, to the end of the string. If the expression evaluates to more than one character, PREFIX ignores all but the first character.
Example
SELECT C1, C2, PREFIX(C1, 1, '.') FROM T1;
C1 C2 PREFIX(C1,1,.
-- -- -------------
test.pref . test
pref.test s pref
2 records selected
SELECT C1, C2, PREFIX(C1, 1, C2) FROM T1;
C1 C2 PREFIX(C1,1,C
-- -- -------------
test.pref . test
pref.test s pref.te
2 records selected
SELECT C1, C2, PREFIX(C1, 1, 'Q') FROM T1;
C1 C2 PREFIX(C1,1,Q
-- -- -------------
test.pref . test.pref
pref.test s pref.test
2 records selected
Notes
