Question

I am supposed to select all the persons born in July (or 07). This did not work:

select * from people where date_trunc('month',dob)='07';

ERROR: invalid input syntax for type timestamp with time zone: “07”
LINE 1: …ct * from people where date_trunc(‘month’,dob)=’07’;

What is the right way?

Answer 1

select * from people where to_char(dob, 'MM') = '09';

gives you all people who where born in September, if the date of birth is stored in a timestamp table column called ‘dob’.
The second param is the date format pattern. All typical patterns should be supported.
E.g.:

select * from people where to_char(dob, 'MON') = 'SEP'; 

would do the same.

look here for timestamp format patterns in Postgres: