Delete query

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What is wrong with following queries?

Query1:
delete from zuser where userid = 1 and user_setid = 1;

ERROR:   ERROR:  Unable to identify an operator '&&' for types 'int4' and
'int4'
        You will have to retype this query using an explicit cast

Query2:
delete from zuser where userid = '1'::int4 and user_setid = '1'::int4;

ERROR:   ERROR:  Unable to identify an operator '&&' for types 'int4' and
'int4'
        You will have to retype this query using an explicit cast

Query3:
delete from zuser where userid = '1'::integer and user_setid =
'1'::integer;

ERROR:   ERROR:  Unable to identify an operator '&&' for types 'int4' and
'int4'
        You will have to retype this query using an explicit cast


thanks,
sandeep