英文:
How to override duplicate keys in Java Map
问题
我有这个作为我的查询。
select a.cust_id,a.cust_name,b.cust_id,b.cust_name
from acustomer a,bcustomer b
DaoImp 使用 Spring NamedJdbcparameterTemplate
方法:
NamedJdbcparameterTemplate temp= new NJPT(datasource);
List<Map<String,Object>> out=temp.quertForList(query,parametermap);
但问题是，每当我在数据库工具中获得这个查询的输出时，我得到4列，但在程序输出中，我只得到2列，即由于Map中具有相同键名，a 的 cust_id 和 cust_name 被b覆盖。
我应该如何修复这个问题，请注意查询每次都会不同，因为我将这个方法用作我的程序的通用方法，输出将是值的列表，因此无法为输出映射任何模型类。
请注意，我希望这个函数是通用的，这意味着查询每次都会改变，输出将是不同类型的。
英文:
I have this as my query.
select a.cust_id,a.cust_name,b.cust_id,b.cust_name
from acustomer a,bcustomer b
DaoImp using Spring NamedJdbcparameterTemplate
method:
NamedJdbcparameterTemplate temp= new NJPT(datasource);
List<Map<String,Object>> out=temp.quertForList(query,parametermap);
But the problem is that whenever I get the output for this query in db tool, I get 4 columns but in program output I am only getting 2 columns, i.e cust_id and cust_name of a is getting overridden by b due to same key name in Map.
How can I fix this, please note the query will be different each time as I am using this method as a general one for my program and output will be a list of values, so cannot map any model class for the output.
Please note I want this function to be generic one which means the query will be changing each time and output will be of different types.
答案1
得分: 5
"Well the easy solution would be to give your fields aliases, so that their keys would be different."
select a.cust_id a_cust_id, a.cust_name a_cust_name, b.cust_id b_cust_id, b.cust_name b_cust_name
from acustomer a, bcustomer b
where a.cust_id=b.cust_id
Then in the map you would find the aliases, a_cust_id, a_cust_name, b_cust_id, b_cust_name.
英文:
Well the easy solution would be to give your fields aliases, so that their keys would be different.
select a.cust_id a_cust_id, a.cust_name a_cust_name, b.cust_id b_cust_id, b.cust_name b_cust_name
from acustomer a, bcustomer b
where a.cust_id=b.cust_id
Then in the map you would find the aliases, a_cust_id, a_cust_name, b_cust_id, b_cust_name.
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