SQL Value Functions

These SQL value functions perform operations on data. There are all kinds of operations that could conceivably be performed on data items, but these are some that are needed most often.

String Value Functions

Function	Effect
SUBSTRING	Extracts a substring from a source string
SUBSTRING SIMILAR	Extracts a substring from a source string, using POSIX-based regular expressions
SUBSTRING_REGEX	Extracts from a string the first occurrence of an XQuery regular expression pattern and returns one occurrence of the matching substring
TRANSLATE_REGEX	Extracts from a string the first or every occurrence of an XQuery regular expression pattern and replaces it or them with an XQuery replacement string
UPPER	Converts a character string to all uppercase
LOWER	Converts a character string to all lowercase
TRIM	Trims off leading or trailing blanks
TRANSLATE	Transforms a source string from one character set to another
CONVERT	Transforms a source string from one character set to another

Numeric Value Functions

Function	Effect
POSITION	Returns the starting position of a target string within a source string
CHARACTER_LENGTH	Returns the number of characters in a string
OCTET_LENGTH	Returns the number of octets (bytes) in a character string
EXTRACT	Extracts a single field from a datetime or interval

Datetime Value Functions

Function	Effect
CURRENT_DATE	Returns the current date
CURRENT_TIME(p)	Returns the current time; (p) is precision of seconds
CURRENT_TIMESTAMP(p)	Returns the current date and the current time; (p) is precision of seconds

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