从SQL中的日期时间戳中提取年份

Question

I am trying to convert a column in a database into a timestamp format, then I want to see the number of counts for each year.

I have:

SELECT
    (column_name::date), count(*)
    EXTRACT(YEAR FROM column_name)
FROM table
GROUP BY column_name;

'I get an error message that says no function matches the given name and argument types. You might need to add explicit type casts.'

Is extract the wrong function?

Answer 1

You probably want something like this if column_name is timestamp

search for EXTRACT documentation

SELECT
    EXTRACT(YEAR FROM column_name), count(*)        
FROM table
GROUP BY EXTRACT(YEAR FROM column_name);

if column_name is string you need to_timestamp() function