This can be seen in Listing H.Type mapping rules from this table are used by default when generating a model from a database with Entity Data Model Wizard in Visual Studio 2008 - 2015 and Create Model Wizard in Entity Developer. Just beware that this parameter has no effect on the SYSTIMESTAMP function. This is a great tool for testing date and time sensitive code. You can set the initialization parameter FIXED_DATE to return a constant value for what is returned from the SYSDATE function. In order to get the system date and time returned in a TIMESTAMP datatype, you can use the SYSTIMESTAMP function such as: In order to get the system date and time returned in a DATE datatype, you can use the SYSDATE function such as : TIME1 TIME2 SECONDS MINUTES HOURS DAYS WEEKS In Listing E, we are only showing 3 place holders for the fractional seconds.Ĭonvert DATE datatype to TIMESTAMP datatypeģ substr((time2-time1),instr((time2-time1),' ')+7,2) seconds,Ĥ substr((time2-time1),instr((time2-time1),' ')+4,2) minutes,ĥ substr((time2-time1),instr((time2-time1),' ')+1,2) hours,Ħ trunc(to_number(substr((time2-time1),1,instr(time2-time1,' ')))) days,ħ trunc(to_number(substr((time2-time1),1,instr(time2-time1,' ')))/7) weeks If you wanted to show the fractional seconds within a TIMESTAMP datatype, look at Listing E.
This is a clear indication that the use of TIMESTAMP datatype should explicitly be used for date and times where a difference in time is of utmost importance, such that Oracle won't even let you compare like values. Beware while the TO_CHAR function works with both datatypes, the TRUNC function will not work with a datatype of TIMESTAMP. Look at Listing D for a formatting of the new TIMESTAMP datatype where everything is the same as formatting the DATE datatype as we did in Listing A. If you are moving a DATE datatype column from one table to a TIMESTAMP datatype column of another table, all you need to do is a straight INSERTSELECT FROM and Oracle will do the conversion for you. This is only because when converting from the DATE datatype that does not have the fractional seconds it defaults to zeros and the display is defaulted to the default timestamp format (NLS_TIMESTAMP_FORMAT). As you can see, there is a fractional seconds part of '.000000' on the end of this conversion. If you want to convert a DATE datatype to a TIMESTAMP datatype format, just use the CAST function as I do in Listing C. Oracle has expanded on the DATE datatype and has given us the TIMESTAMP datatype which stores all the information that the DATE datatype stores, but also includes fractional seconds. One of the main problems with the DATE datatype was its' inability to be granular enough to determine which event might have happened first in relation to another event.