问个简单的有关问题动态sql语句的参数

问个简单的问题动态sql语句的参数
LsSQL = "update lxscq set zhshh = :maxzhshh where bh =:bh"
execute immediate :LsSQL using sqlca;

这样写有问题吗？怎么存不了数据呢？

------解决方案--------------------
有问题
要么这样：
update lxscq set zhshh = :maxzhshh where bh =:bh;
要么这样：
LsSQL = "update lxscq set zhshh = " + string(maxzhshh) + " where bh = " + string(bh)
execute immediate :LsSQL using sqlca;
------解决方案--------------------
LsSQL = "update lxscq set zhshh = '" + string(maxzhshh) + "' where bh = " + string(bh)
execute immediate :LsSQL using sqlca;