Date Format Query Table

Date Format Query Table

Dear Experts.

I´m trying a Query table and i want to create a new column with date format but when i run the Query the column is not recognize as a date.

I have tried 01/10/2015; 01-10-2015 and 01.10.2015.

¿How I must write the SQL sentence to Zoho recognize as a date?

 
case a."mes" 
when '10'  then '01.10.2015'
when '11'  then '01.11.2015'
when '12'  then '01.12.2015'
end 'Mes Real',