After accessing your query in Report Builder (Tool #100), select the option to Choose Files and select to add the DATELOOKUP table. To join this file, select 1 or 2 (matched records or matched with primary) and join by the compatible date fields. 

As an example, if your original file's date field is OPENDT and the format is MMDDYY layout, you would then match the OPENDT field with the matching field format in the DATELOOKUP table, DTMMDDYY. 
 
Once the DATELOOKUP table is linked in, you need to find and select the DTISODATE field for your report (under Choose Fields) and use that one to replace the original OPENDT.

• NOTE: The date lookup only contains dates between January 1, 1930 and December 31, 2050. Because of this, this solution is not a good solution for dates too far in the future or the past.
• Be mindful if you use this solution with a two-digit years. For example, the year '45 could match 1945 and 2045.