SQL Value Functions

You use SQL value expressions to combine two or more values. Several kinds of SQL value expressions exist, corresponding to the different data types; the following tables list string, numeric, and datetime values, functions, and effects:

String Value Functions

Function	Effect
SUBSTRING	Extracts a substring from a source 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	Same as TRANSLATE. (It 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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