复杂查询

QuickDAO提供了丰富的单表查询操作.

Person实体类

  1. public class Person {
  2.     @Id(strategy = IdStrategy.AutoIncrement)
  3.     private long id;
  4.     private String username;
  5.     private String password;
  6.     private int type;
  7. }

Condition对象

调用dao.query(Person.class);就得到了Person类的Condition对象,Condition接口定义了大量添加条件查询的方法.

  1. Condition condition = dao.query(Person.class)
  2.     //添加distinct关键字
  3.     .distinct()
  4.     //username is null
  5.     .addNullQuery("username")
  6.     //username is not null
  7.     .addNotNullQuery("username")
  8.     //username is not null and username = ''
  9.     .addEmptyQuery("username")
  10.     //username is not null and username != ''
  11.     .addNotEmptyQuery("username")
  12.     //type in (1,2)
  13.     .addInQuery("type","1","2")
  14.     //type not in (3,4)
  15.     .addNotInQuery("type","3","4")
  16.     //type between 1 and 2
  17.     .addBetweenQuery("type",1,2)
  18.     //username like 'quickdao%'
  19.     .addLikeQuery("username","quickdao%")
  20.     //type >= 1
  21.     .addQuery("type",">=","1")

这些方法名见名知义,同时也有详细的JavaDoc文档.所有的查询条件接口以addXXXQuery命名,您可以很方便的分辨出哪些是查询方法接口.

or查询

您可以添加or查询条件

  1. //select distinct id,username,password,type from person where username like 'a%' or username like 'b%' 
  2. Condition condition = dao.query(Person.class)
  3.            .distinct()
  4.             .addLikeQuery("username","a%");
  5. condition.or().addQuery("username","b%")
  6. Response response = condition.execute();

union查询

您可以union多个表,但是您需要保证union关联的表的返回的字段个数保持一致.

您可以指定使用union或者union all类型进行连接,union方法默认采用union连接方式.

  1. Condition unionCondition1 = dao.query(Person.class)
  2.     .addQuery("username","a")
  3.     .addColumn("username","password");
  5. Condition unionCondition2 = dao.query(Person.class)
  6.     .addQuery("username","b")
  7.     .addColumn("username","password");
  9. Response response = dao.query(Person.class)
  10.                     .union(unionCondition1)
  11.                     .union(unionCondition2,UnionType.UnionAll)
  12.                     .addColumn("username","password")
  13.                     .execute();

addRawQuery

addRawQuery方法将给定的参数直接拼接到SQL语句上,适用于查询条件无法用现有API生成的情况

  1. Condition condition = dao.query(Person.class)
  2.      .addRawQuery("username = (select max(username) from person where age = t.age) ")

Response 对象

调用Condition实例的execute()方法就得到Response实例对象.Response接口定义获取返回结果的方法.不同的返回结果对应着不同的查询条件.

  1. Condition condition = dao.query(User.class);
  2. Response response = condition.execute();
  3. List<User> userList = response.getList();

clone方法

Condition实现了Cloneable接口.