Check to see if customer exist in second table. Help needs withpsql

psql
I have two tables , table A and Table b. Table A has list of about 60000
customers ID with all their details and Table B had customer is and age for
over 500000 rows of customers.

I need a query that will take a customer from table a and if that customer
exists in table B then insert a yes in a new column in table a. Basically
what I want to end up with in table a , is all the customers in this table
and if they exist in table B then yes in a column. I.e the final result will
be 60000 customers and additional column at the end with yes or no depending
if they exist in table B.

Any help is appreciate it



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