Hello,
Please help me to understand what I am going to implement for Timestamp. Do we
need LOCALTIMESTAMP implementation? See the comparisons below::
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LOCALTIMESTAMP
It's often important to get the value of current date and time. Below are the
functions used to do that in the different implementations.
Standard The current timestamp (without time zone) is retrieved with the
LOCALTIMESTAMP function which may be used as:
SELECT LOCALTIMESTAMP ...
or
SELECT LOCALTIMESTAMP(precision) ...
Note that "SELECT LOCALTIMESTAMP() ..." is illegal: If you don't care about the
precision, then you must not use any parenthesis.
If the DBMS supports the non-core time zone features (feature ID F411), then it
must also provide the functions CURRENT_TIMESTAMP and
CURRENT_TIMESTAMP(precision) which return a value of type TIMESTAMP WITH TIME
ZONE. If it doesn't support time zones, then the DBMS must not provide a
CURRENT_TIMESTAMP function.
PostgreSQL Follows the standard.
Documentation
DB2 Doesn't have the LOCALTIMESTAMP function.
Instead, it provides a special, magic value ('special register' in IBM
language), CURRENT_TIMESTAMP (alias to 'CURRENT TIMESTAMP') which may be used
as though it were a function without arguments. However, since DB2 doesn't
provide TIMESTAMP WITH TIME ZONE support, the availability of CURRENT_TIMESTAMP
could be said to be against the standard—at least confusing.
Documentation
MSSQL Doesn't have the LOCALTIMESTAMP function.
Instead, it has CURRENT_TIMESTAMP which—however—doesn't return a value of
TIMESTAMP WITH TIME ZONE, but rather a value of MSSQL's DATETIME type (which
doesn't contain time zone information).
Documentation
MySQL Follows the standard.
Documentation
Oracle Follows the standard.
Informix On my TODO.
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Thanks,
[email protected]
