求PL/SQL的一条语句

[bibidog]

我现在想写一个过程，过程中需要做一个判断表内是否存在一条记录
Create Procedure produce11
(
V_TableID in integer,
V_key1 in integer,
V_key2 in integer,
V_key3 in varchar2,
V_key4 in varchar2,
V_num out integer)
As
V_cnt integer;
Begin
if (V_key2 is not null) and exists(select 1 from table where BMID V_key2 and CWareID = V_key1) then
V_num:=1;
else
V_num:=0;
end if;
end produce11;
就是中间的那条exists语句