Honestly, you do it in PostgreSQL the same way you do it in all the other SQL RDBMSs.
Emphasizing "in PostgreSQL" is nonsensical - it isn't like the OP specified that they know how to do it in some other RDBMS and are trying to convert their knowledge to PostgreSQL.
On 11/24/22 06:01, Rama Krishnan wrote:
I want to get the unique wallet_id from this table even it was repeated on multiple occasions I should calculate only once as well as if the wallet_id was calculated on previous month it shouldn't be calculate on next months
You need a subquery to compute the month in which each wallet_id should appear (group by wallet_id with min(date) probably), then you can group on the min(date) column and count the wallets.