How to Extract Year from DATE in POSTGRESQL

Date is in 'YYYY-MM-DD' text format, now I need to extract the year part which must be in numeric. I need this conversion to be done in single step, Since I need to use in other application where i cannot create new variable.

TO_DATE(t0.AESTDTC,'YYYY-MM-DD'),'YYYY-MM-DD' with this i was able to convert to date but Now i need to Extract the year from this date in single step? can any one help me?

Try

select date_part('year', your_column) from your_table;

or

select extract(year from your_column) from your_table;

This line solved my same problem in postgresql:

SELECT DATE_PART('year', column_name::date) from tableName;

If you want month, then simply replacing year with month solves that as well and likewise.