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

About This Article

This article is from the book:

About the book author:

Allen G. Taylor is a 30-year veteran of the computer industry and the author of over 40 books, including SQL For Dummies and Crystal Reports For Dummies. He lectures nationally on databases, innovation, and entrepreneurship. He also teaches database development internationally through a leading online education provider.

This article can be found in the category: