In Oracle Database, the LOCALTIMESTAMP() function returns the current date and time in the session time zone in a value of data type TIMESTAMP.
It’s similar to CURRENT_TIMESTAMP, except that CURRENT_TIMESTAMP returns a TIMESTAMP WITH TIME ZONE value.
In Oracle Database, the SYSTIMESTAMP function returns the system date, including fractional seconds and time zone, of the system on which the database resides.
The returned value is of type TIMESTAMP WITH TIME ZONE.
In Oracle Database, the SYSDATE function returns the current date and time set for the operating system on which the database server resides.
The returned value is of type DATE.
In Oracle Database, the EXTRACT(datetime) function extracts and returns the value of a specified datetime field from a datetime or interval expression.
In Oracle, the TRANSLATE(...USING) function converts its argument into the character set specified for conversions between the database character set and the national character set.
This function is not to be confused with the TRANSLATE() function, which allows you to make several single-character, one-to-one substitutions in one operation.
The TRANSLATE(...USING) function is supported in Oracle primarily for ANSI compatibility. Oracle recommends that we use the TO_CHAR() and TO_NCHAR() functions instead.
In Oracle, the LENGTH() function returns the length of its argument.
LENGTH() can also be thought of as a group of functions. There are five separate functions; LENGTH(), LENGTHB(), LENGTHC(), LENGTH2(), and LENGTH4(). Each function calculates the length in a different way.
When working with functions that return dates, Oracle Database returns these dates based on the value of the NLS_DATE_FORMAT parameter.
There is also an NLS_TIMESTAMP_FORMAT parameter and an NLS_TIMESTAMP_TZ_FORMAT parameter, both of which have a datetime format mask that can be specified separately.
All of these parameters have their default values derived from the NLS_TERRITORY parameter (which by default, is operating system-dependent).
So, to change the date format for your session, you can either update the NLS_TERRITORY parameter, or explicitly update each parameter individually.
This article provides examples of checking and changing these values, and viewing the results.
Continue readingBelow is a list of numeric functions in Oracle Database.
Continue readingIn Oracle, the INSTR() function searches for a substring in a given string, and returns an integer indicating the position of the first character of this substring. If the substring isn’t found, the function returns 0.
INSTR() requires at least two arguments; the string, and the substring. It also accepts an optional third and fourth arguments that allows you to specify the starting position to search, and which occurrence to search for.
INSTR() can also be thought of as a group of functions. There are five separate functions; INSTR(), INSTRB(), INSTRC(), INSTR2(), and INSTR4(). Each function calculates the length in a different way.
In Oracle Database, the ASCII() function returns the decimal representation in the database character set of the first character of its argument.