The TIMESTAMP function converts a DATE or TIMESTAMP type expression to DATETIME type.
If the DATE format string ('YYYY-MM-DD' or 'MM/DD/YYYY') or TIMESTAMP format string ('YYYY-MM-DD HH:MI:SS' or 'HH:MI:SS MM/DD/ YYYY') is specified as the first argument, the function returns it as DATETIME.
If the TIME format string ('HH:MI:SS') is specified as the second, the function adds it to the first argument and returns the result as a DATETIME type. If the second argument is not specified, 12:00:00.000 AM is specified by default.
TIMESTAMP(date [,time])
SELECT TIMESTAMP('2009-12-31'), TIMESTAMP('2009-12-31','12:00:00');
timestamp('2009-12-31') timestamp('2009-12-31', '12:00:00')
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12:00:00.000 AM 12/31/2009 12:00:00.000 PM 12/31/2009
SELECT TIMESTAMP('2010-12-31 12:00:00','12:00:00');
timestamp('2010-12-31 12:00:00', '12:00:00')
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12:00:00.000 AM 01/01/2011
SELECT TIMESTAMP('13:10:30 12/25/2008');
timestamp('13:10:30 12/25/2008')
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01:10:30.000 PM 12/25/2008