两张表，如何把B表中的billmoney字段的合计数更新到A表中的bxmoney

tableA 字段 billid bxmoney
2001

tableB 字段 billid billmoney
2001 100
2001 150
2001 300

update tableA set bxmoney = (select sum(billmoney) from tableB where tableb.billid = tablea.billid GROUP BY tableb.billid);

update tableA set bxmoney = (select sum(billmoney) from tableB where tableB.billid = tableA.billid GROUP BY tableB.billid);