EJB-QL語法
該語句由如下4部分組成：
1.必須的Select從句
2.必須的From從句
3.可選的Where從句
4.可選的Order By從句


Where從句
例如：Select Object(o) from Order as o where o.name IS NOT EMPTY

處理輸入參數:

findProductByDescription(String s)

Select Object(p) from Product as p where p.description=?1


findUserByNameAndPwd(String name,String pwd)

Select Object(c) from Users as c where c.name=?1 and c.password=?2