oracle sql 游标的简单用法（tip:sql中两个单引号表示一个单引号）

--游标遍历某个字段 （打印出来）
declare
            res_sql varchar2(2000);
cursor cur is
            select f_dcname from W_EC_PLACESTATION_COLLECT t
            where f_collectdate >= TRUNC(TO_DATE('2018-09-01','yyyy-MM-dd'),'month') AND f_collectdate < TO_DATE('2018-09-30','yyyy-MM-dd')+1
            group by f_dcname;
begin
             for i in cur loop
                 res_sql :=i.f_dcname;
                 dbms_output.put_line(res_sql);
             end loop;
end;

--变形

declare
res_sql varchar2(2000);
cursor cur is
select f_dcname from W_EC_PLACESTATION_COLLECT t
where f_collectdate >= TRUNC(TO_DATE('2018-09-01','yyyy-MM-dd'),'month')
AND f_collectdate < TO_DATE('2018-09-30','yyyy-MM-dd')+1
group by f_dcname;
begin
for i in cur loop
res_sql :=i.f_dcname;
res_sql :='select count(*) from W_EC_PLACESTATION_COLLECT '||
'where f_collectdate >= TRUNC(TO_DATE(''2018-09-01'',''yyyy-MM-dd''),''month'') '||
'AND f_collectdate < TO_DATE(''2018-09-30'',''yyyy-MM-dd'')+1 '||
'and f_dcname='||i.f_dcname;
dbms_output.put_line(res_sql);
end loop;
end;