SQL查询中的多个过滤器（JDBC）

Question

I came up with the solution and wanted to know any other better approach to handle this problem ?

I am not using hibernate instead using JDBC template.

I've Employee table with following attributes

1. id (Auto generated Primary key)
2. first_name
3. last_name
4. salary

Requirement : 1.Write getByFilter API in EmployeeDAO. 2.If any of the field is null in the filter object ignore that in the query.

Solution : I came up with following generic solution.

public List<Employee> getByFilter(Employee filter){
NamedParameterJdbcTemplate namedParameterJdbcTemplate = new NamedParameterJdbcTemplate(
            getDataSource());

String query = "SELECT ID as id,"+
               "first_name as firstName,"+
               "last_name as lastName,"+
               "dob as dob ,"+
               "department_name as departmentName,"+
               "salary as salary"+
               "FROM employee "+
               "WHERE "+
               "(:id IS NULL OR id = :id ) AND"+ // Handling second requirement if field is null
               "(:first_name IS NULL or first_name = :firstName  ) AND"+      
               "(:last_name  IS NULL or first_name = :lastName) AND"+
               "(:salary     IS NULL OR salary = :salary)";

    Map<String, Object> aMap = new HashMap<String, Object>();
    aMap.put("id", filter.getId());
    aMap.put("firstName", filter.getFirstName());
    aMap.put("lastName",  filter.getLastName());
    aMap.put("salary", filter.getSalary());
    return namedParameterJdbcTemplate.query(getQuery, aMap,
            new BeanPropertyRowMapper<Employee>(Employee.class));
}

Answer 1

A better option can be to use hibernate criteria so that it will reduce the query

Criteria criteria = session.createCriteria(classname);
criteria.add(Restrictions.eq("first_name", firstName));
criteria.add(Restrictions.eq("last_name", lastName));
//same for all properties
//for checking null it will be like
    criteria.add(Restrictions.isNotNull("id "));

//same for others

hibernate criteria provides better options to write the database query and easier and cleaner approach