Extracts the substring of string starting at the start'th character if that is specified, and stopping after count characters if that is specified.
substring ( string text [ FROM start integer ] [ FOR count integer ] ) → textExtracts the substring of
string starting at the start'th character if that is specified, and stopping after count characters if that is specified. Provide at least one of start and count.substring('Thomas' from 2 for 3) → homsubstring('Thomas' from 3) → omassubstring('Thomas' for 2) → Thsubstring ( string text FROM pattern text ) → textExtracts the first substring matching POSIX regular expression; see Section 9.7.3.
substring('Thomas' from '...$') → massubstring ( string text SIMILAR pattern text ESCAPE escape text ) → textExtracts the first substring matching SQL regular expression; see Section 9.7.2. The first form has been specified since SQL:2003; the second form was only in SQL:1999 and should be considered obsolete.
substring('Thomas' similar '%#"o_a#"_' escape '#') → omasubstring ( string text FROM pattern text FOR escape text ) → textExtracts the first substring matching SQL regular expression; see Section 9.7.2. The first form has been specified since SQL:2003; the second form was only in SQL:1999 and should be considered obsolete.
substring('Thomas' similar '%#"o_a#"_' escape '#') → omasubstring ( bytes bytea [ FROM start integer ] [ FOR count integer ] ) → byteaExtracts the substring of
bytes starting at the start'th byte if that is specified, and stopping after count bytes if that is specified. Provide at least one of start and count.substring('\x1234567890'::bytea from 3 for 2) → \x5678substring ( bits bit [ FROM start integer ] [ FOR count integer ] ) → bitExtracts the substring of
bits starting at the start'th bit if that is specified, and stopping after count bits if that is specified. Provide at least one of start and count.substring(B'110010111111' from 3 for 2) → 00
substring(string similar pattern escape escape-character)The
substring function with three parameters provides extraction of a substring that matches an SQL regular expression pattern. The function can be written according to standard SQL syntax:substring(string from pattern for escape-character)The
substring function with three parameters provides extraction of a substring that matches an SQL regular expression pattern. The function can be written according to standard SQL syntax:substring(string, pattern, escape-character)As with
SIMILAR TO, the specified pattern must match the entire data string, or else the function fails and returns null. To indicate the part of the pattern for which the matching data sub-string is of interest, the pattern should contain two occurrences of the escape character followed by a double quote ("). The text matching the portion of the pattern between these separators is returned when the match is successful.Definition snapshot: 2026-09-14T13:14:25.684213+00:00@99e6866c · English manual source