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305 lines
7.8 KiB
Markdown
305 lines
7.8 KiB
Markdown
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# Mybatis-Flex 一个优雅的 Mybatis 增强框架
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## 特征
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- 1、很轻量，整个框架只依赖 Mybatis 再无其他第三方依赖
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- 2、Entity 类的基本增删改查、以及分页查询
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- 3、Row 通用映射支持，可以无需实体类对数据库进行增删改查
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- 4、支持多种数据库类型，自由通过方言持续扩展
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- 5、支持联合主键，以及不同的主键内容生成策略
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- 6、极其友好的 SQL 联动查询，IDE 自动提示不再担心出错
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- 7、更多小惊喜
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## hello world
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**第一步：编写 Entity 实体类**
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```java
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@Table("tb_account")
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public class Account {
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@Id()
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private Long id;
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private String userName;
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private Date birthday;
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private int sex;
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//getter setter
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}
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```
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**第二步，编写 Mapper 类，并继承 BaseMapper**
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```java
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public interface AccountMapper extends BaseMapper<Account> {
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//只需定义 Mapper 接口即可，可以无任何内容。
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}
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```
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**第三步：开始查询数据**
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示例 1：查询 1 条数据
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```java
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class HelloWorld {
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public static void main(String... args) {
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HikariDataSource dataSource = new HikariDataSource();
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dataSource.setJdbcUrl("jdbc:mysql://127.0.0.1:3306/mybatis-flex");
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dataSource.setUsername("username");
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dataSource.setPassword("password");
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MybatisFlexBootstrap.getInstance()
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.setDatasource(dataSource)
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.addMapper(AccountMapper.class)
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.start();
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//示例1：查询 id=100 条数据
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Account account = MybatisFlexBootstrap.getInstance()
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.execute(AccountMapper.class, mapper ->
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mapper.selectOneById(100)
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);
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}
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}
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```
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示例2：查询列表
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```java
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class HelloWorld {
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public static void main(String... args) {
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HikariDataSource dataSource = new HikariDataSource();
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dataSource.setJdbcUrl("jdbc:mysql://127.0.0.1:3306/mybatis-flex");
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dataSource.setUsername("username");
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dataSource.setPassword("password");
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MybatisFlexBootstrap.getInstance()
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.setDatasource(dataSource)
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.addMapper(AccountMapper.class)
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.start();
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//示例2：通过 QueryWrapper 构建条件查询数据列表
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QueryWrapper query = QueryWrapper.create()
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.select()
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.from(ACCOUNT)
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.where(ACCOUNT.ID.ge(100))
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.and(ACCOUNT.USER_NAME.like("张").or(ACCOUNT.USER_NAME.like("李")));
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// 执行 SQL：
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// ELECT * FROM `tb_account`
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// WHERE `tb_account`.`id` >= 100
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// AND (`tb_account`.`user_name` LIKE '%张%' OR `tb_account`.`user_name` LIKE '%李%' )
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List<Account> accounts = MybatisFlexBootstrap.getInstance()
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.execute(AccountMapper.class, mapper ->
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mapper.selectListByQuery(query)
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);
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}
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}
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```
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示例3：分页查询
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```java
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class HelloWorld {
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public static void main(String... args) {
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HikariDataSource dataSource = new HikariDataSource();
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dataSource.setJdbcUrl("jdbc:mysql://127.0.0.1:3306/mybatis-flex");
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dataSource.setUsername("username");
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dataSource.setPassword("password");
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MybatisFlexBootstrap.getInstance()
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.setDatasource(dataSource)
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.addMapper(AccountMapper.class)
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.start();
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// 示例3：分页查询
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// 查询第 5 页，每页 10 条数据，通过 QueryWrapper 构建条件查询
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QueryWrapper query = QueryWrapper.create()
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.select()
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.from(ACCOUNT)
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.where(ACCOUNT.ID.ge(100))
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.and(ACCOUNT.USER_NAME.like("张").or(ACCOUNT.USER_NAME.like("李")))
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.orderBy(ACCOUNT.ID.desc());
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// 执行 SQL：
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// ELECT * FROM `tb_account`
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// WHERE `tb_account`.`id` >= 100
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// AND (`tb_account`.`user_name` LIKE '%张%' OR `tb_account`.`user_name` LIKE '%李%' )
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// ORDER BY `tb_account`.`id` DESC
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// LIMIT 40,10
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Page<Account> accounts = MybatisFlexBootstrap.getInstance()
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.execute(AccountMapper.class, mapper ->
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mapper.paginate(5, 10, query)
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);
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}
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}
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```
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## QueryWrapper 示例
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### select *
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```java
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QueryWrapper query=new QueryWrapper();
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query.select().from(ACCOUNT)
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// SQL:
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// SELECT * FROM tb_account
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```
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### select columns
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```java
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QueryWrapper query=new QueryWrapper();
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query.select(ACCOUNT.ID,ACCOUNT.USER_NAME).from(ACCOUNT)
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// SQL:
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// SELECT tb_account.id, tb_account.user_name
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// FROM tb_account
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```
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```java
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QueryWrapper query=new QueryWrapper();
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query.select(ACCOUNT.ALL_COLUMNS).from(ACCOUNT)
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// SQL:
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// SELECT tb_account.id, tb_account.user_name, tb_account.birthday,
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// tb_account.sex, tb_account.is_normal
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// FROM tb_account
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```
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### select functions
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```java
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QueryWrapper query=new QueryWrapper()
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.select(ACCOUNT.ID
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,ACCOUNT.USER_NAME
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,max(ACCOUNT.BIRTHDAY)
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,avg(ACCOUNT.SEX).as("sex_avg"))
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.from(ACCOUNT);
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// SQL:
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// SELECT tb_account.id, tb_account.user_name,
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// MAX(tb_account.birthday),
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// AVG(tb_account.sex) AS sex_avg
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// FROM tb_account
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```
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### where
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```java
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QueryWrapper queryWrapper=QueryWrapper.create()
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.select()
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.from(ACCOUNT)
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.where(ACCOUNT.ID.ge(100))
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.and(ACCOUNT.USER_NAME.like("michael"));
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// SQL:
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// SELECT * FROM tb_account
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// WHERE tb_account.id >= ?
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// AND tb_account.user_name LIKE ?
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```
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### exists, not exists
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```java
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QueryWrapper queryWrapper=QueryWrapper.create()
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.select()
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.from(ACCOUNT)
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.where(ACCOUNT.ID.ge(100))
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.and(
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exist(
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selectOne().from(ARTICLE).where(ARTICLE.ID.ge(100))
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)
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);
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// SQL:
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// SELECT * FROM tb_account
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// WHERE tb_account.id >= ?
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// AND EXIST (
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// SELECT 1 FROM tb_article WHERE tb_article.id >= ?
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// )
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```
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### and (...) or (...)
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```java
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QueryWrapper queryWrapper=QueryWrapper.create()
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.select()
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.from(ACCOUNT)
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.where(ACCOUNT.ID.ge(100))
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.and(ACCOUNT.SEX.eq(1).or(ACCOUNT.SEX.eq(2)))
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.or(ACCOUNT.AGE.in(18,19,20).or(ACCOUNT.USER_NAME.like("michael")));
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// SQL:
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// SELECT * FROM tb_account
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// WHERE tb_account.id >= ?
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// AND (tb_account.sex = ? OR tb_account.sex = ? )
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// OR (tb_account.age IN (?,?,?) OR tb_account.user_name LIKE ? )
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```
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### group by
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```java
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QueryWrapper queryWrapper=QueryWrapper.create()
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.select()
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.from(ACCOUNT)
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.groupBy(ACCOUNT.USER_NAME);
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// SQL:
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// SELECT * FROM tb_account
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// GROUP BY tb_account.user_name
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```
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### having
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```java
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QueryWrapper queryWrapper=QueryWrapper.create()
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.select()
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.from(ACCOUNT)
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.groupBy(ACCOUNT.USER_NAME)
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.having(ACCOUNT.AGE.between(18,25));
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// SQL:
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// SELECT * FROM tb_account
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// GROUP BY tb_account.user_name
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// HAVING tb_account.age BETWEEN ? AND ?
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```
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### jion
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```java
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QueryWrapper queryWrapper = QueryWrapper.create()
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.select()
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.from(ACCOUNT)
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.leftJoin(ARTICLE).on(ACCOUNT.ID.eq(ARTICLE.ACCOUNT_ID))
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.where(ACCOUNT.AGE.ge(10));
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// SQL:
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// SELECT * FROM tb_account
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// LEFT JOIN tb_article
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// ON tb_account.id = tb_article.account_id
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// WHERE tb_account.age >= ?
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```
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### 可能存在问题
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**如何通过实体类 Account.java 生成 QueryWrapper 所需要的 "ACCOUNT" 类 ?**
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答：通过开发工具构建项目（如下图），或者执行 maven 编译命令: `mvn clean package`
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## 更多示例
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- 1、[Mybatis-Flex 原生（无其他依赖）](./mybatis-flex-test/mybatis-flex-native-test)
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- 2、[Mybatis-Flex with Spring](./mybatis-flex-test/mybatis-flex-spring-test)
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- 3、[Mybatis-Flex with Spring boot](./mybatis-flex-test/mybatis-flex-spring-boot-test)
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