fix bug for statistic with delete statement:

[kenlee1988]

test case:

delete from tb1;
delete tb1 from tb1;

delete tb1 from tb1, tb2 where tb1.f1 = tb2.f1;
delete tb1 from tb1, tb2 where tb1.f1 = tb2.f1;
delete tb1, tb2 from tb1, tb2 where tb1.f1 = tb2.f1;

delete tb1 from tb1 left join tb2 on tb1.f1 = tb2.f1;
delete tb2 from tb1 left join tb2 on tb1.f1 = tb2.f1;
delete tb1, tb2 from tb1 left join tb2 on tb1.f1 = tb2.f1;

delete t1 from tb1 as t1, tb2 as t2 where t1.f1 = t2.f1;
delete t2 from tb1 as t1, tb2 as t2 where t1.f1 = t2.f1;
delete t1, t2 from tb1 as t1, tb2 as t2 where t1.f1 = t2.f1;

delete t1 from tb1 as t1 left join tb2 as t2 on t1.f1 = t2.f1;
delete t2 from tb1 as t1 left join tb2 as t2 on t1.f1 = t2.f1;
delete t1, t2 from tb1 as t1 left join tb2 as t2 on t1.f1 = t2.f1;