In Oracle Database, the CURRENT_DATE function returns the current date in the session time zone, in a value in the Gregorian calendar of data type DATE.
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CURRENT_TIMESTAMP() Function in Oracle
In Oracle Database, the CURRENT_TIMESTAMP() function returns the current date and time in the session time zone, in a value of data type TIMESTAMP WITH TIME ZONE.
It’s similar to LOCALTIMESTAMP, except that LOCALTIMESTAMP returns a TIMESTAMP value.
LOCALTIMESTAMP() Function in Oracle
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.
SYSTIMESTAMP Function in Oracle
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.
SYSDATE Function in Oracle
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.
EXTRACT (datetime) Function in Oracle
In Oracle Database, the EXTRACT(datetime) function extracts and returns the value of a specified datetime field from a datetime or interval expression.
TRANSLATE(… USING) Function in Oracle
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.
LENGTH() Function in Oracle
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.
INSTR() Function in Oracle
In 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.
ASCII() Function in Oracle
In Oracle Database, the ASCII() function returns the decimal representation in the database character set of the first character of its argument.