如何在jdbc中获取记录相同的列名称值？

Question

I had retrieved all records from db which have fields name,email,id,manager and I need to get all data records which have same manager and save it to list how can I to do it?

I had retrieved values from db has

 List<Map<String, String> dbData=new ArrayList<>();
while(query.next()){
 LinkedHashMap<String,String> rowData=new LinkedHashMal<>();
 for(columns=1;columns<total columns; columns++){
 rowData.put(columnNames,query.getString(columnNames.get(columns));
 }
 dbData.add(rowData);
}

Where columnNames is header list which contains all headers of the column.

So I need to get all records of same manager and export it to separate Excel file

Answer 1

If you want to filter by a certain manager you have to include the manager as a WHERE clause of your query. Something like:

SELECT name, email, id, manager FROM Table WHERE manager = 'manager1'

Once you have all records you wanted you can iterate through your ResultSet and add them too your list.

For more info you can check this link

Answer 2

First, you read all the rows from the database into Java objects.

Assuming you read the data into a List<Record> , you can then group the data using Java 8 streams:

List<Record> rows = ...
Map<String, List<Record>> byManager = rows.stream()
        .collect(Collectors.groupingBy(Record::getManager, Collectors.toList()));

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UPDATE

If the record is a Map<String, String> mapping column name to stringified value, the code would be:

List<Map<String, String>> rows = ...
Map<String, List<Map<String, String>>> byManager = rows.stream()
        .collect(Collectors.groupingBy(row -> row.get("manager"), Collectors.toList()));