In PostgreSQL, the statement_timestamp() function returns the current date and time (including the time zone offset), at the start of the current statement.
The function doesn’t accept any parameters, so you can’t specify its precision.
Also, statement_timestamp() is a non-SQL-standard function.
In PostgreSQL, the transaction_timestamp() function returns the current date and time (including the time zone offset), at the start of the current transaction.
It’s the equivalent of the traditional Postgres function now().
It’s also similar to the current_timestamp function (when called without an argument), except that it’s named to clearly reflect what it does.
The transaction_timestamp() function doesn’t accept any parameters, so you can’t specify its precision, whereas current_timestamp can be called with or without a precision parameter.
Also, transaction_timestamp() is a non-SQL-standard function.
In PostgreSQL, the now() function returns the current date and time (including the time zone offset), at the start of the current transaction.
It’s the equivalent of the transaction_timestamp() function.
It’s also similar to the current_timestamp function (when called without an argument).
The now() function doesn’t accept any parameters, so you can’t specify its precision, whereas current_timestamp can be called with or without a precision parameter.
Also, now() is non-SQL-standard (as is the transaction_timestamp() function).
In PostgreSQL, timeofday() is a non-SQL-standard time function that returns the current date and time, with the time zone abbreviation.
It’s similar to the clock_timestamp() function, except that it returns its result as a formatted text string rather than a timestamp with time zone value.
The result of both functions changes throughout the execution of a statement. Therefore, you could get a different result in different parts of the statement if you call the functions multiple times within a single statement.
Continue readingIn PostgreSQL, the localtime function returns the local time of the day, without the time zone offset.
If you need the time zone offset, use current_time() instead.
In PostgreSQL, the current_time function returns the current time, including the time zone offset.
The time returned is based on the start time of the current transaction.
Continue readingIn PostgreSQL, the current_date function returns the current date.
In PostgreSQL, the date_trunc() function truncates a date/time value to a specified precision.
It can also truncate the value to a specified precision in a specified time zone.
You could think of it as a date version of the trunc() function (which truncates numbers).
In PostgreSQL, you can use the to_number() function to convert a string to a numeric value.
More specifically, it converts the string representation of a number to a numeric value.
For example, if you have $1,234.50 as a string, you can use to_number() to convert that to an actual number that uses the numeric data type.
In PostgreSQL, atanh() is a hyperbolic function that returns the inverse hyperbolic tangent of its argument.
The argument and return value are provided as a double precision value.
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