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update 优化文档细节及代码格式
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luozhan
parent
cfb77c493c
commit
c2eb57e102
@ -21,7 +21,7 @@ public class AccountController {
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@GetMapping("/accounts")
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List<Account> selectList() {
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//构造 QueryWrapper
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//构造 QueryWrapper，也支持使用 QueryWrapper.create() 构造，效果相同
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QueryWrapper query = new QueryWrapper();
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query.where(ACCOUNT.ID.ge(100));
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@ -51,7 +51,7 @@ where id >= 100
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## select *
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```java
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QueryWrapper query=new QueryWrapper();
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QueryWrapper query = new QueryWrapper();
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query.select(ACCOUNT.ID, ACCOUNT.USER_NAME)
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.from(ACCOUNT)
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```
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@ -49,8 +49,25 @@ MyBatis-Flex 主要是和 `MyBatis-Plus` 与 `Fluent-Mybatis` 对比，内容来
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**MyBatis-Flex：**
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一般方式：
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````java
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QueryCondition condition = EMPLOYEE.LAST_NAME.like("B")
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QueryWrapper query = QueryWrapper.create()
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.where(EMPLOYEE.LAST_NAME.like(searchWord)) //条件为null时自动忽略
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.and(EMPLOYEE.GENDER.eq(1))
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.and(EMPLOYEE.AGE.gt(24));
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List<Employee> employees = employeeMapper.selectListByQuery(query);
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````
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更简单一点：
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````java
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QueryWrapper query = select()
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.where(EMPLOYEE.LAST_NAME.like(searchWord))
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.and(EMPLOYEE.GENDER.eq(1))
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.and(EMPLOYEE.AGE.gt(24));
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List<Employee> employees = employeeMapper.selectListByQuery(query);
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````
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换一种方式：
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````java
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QueryCondition condition = EMPLOYEE.LAST_NAME.like(searchWord)
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.and(EMPLOYEE.GENDER.eq(1))
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.and(EMPLOYEE.AGE.gt(24));
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List<Employee> employees = employeeMapper.selectListByCondition(condition);
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@ -59,21 +76,19 @@ List<Employee> employees = employeeMapper.selectListByCondition(condition);
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**MyBatis-Plus：**
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````java
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QueryWrapper<Employee> queryWrapper = new QueryWrapper<>();
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queryWrapper
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.like("last_name","B")
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.eq("gender",1)
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.gt("age",24);
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QueryWrapper<Employee> queryWrapper = Wrappers.query()
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.like(searchWord != null, "last_name", searchWord)
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.eq("gender", 1)
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.gt("age", 24);
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List<Employee> employees = employeeMapper.selectList(queryWrapper);
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````
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或者 MyBatis-Plus 的另一种写法：
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或者 MyBatis-Plus 的lambda写法：
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```java
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LambdaQueryWrapper<Employee> queryWrapper = new LambdaQueryWrapper<>();
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queryWrapper
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.like(Employee::getUserName,"B")
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.eq(Employee::getGender,1)
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.gt(Employee::getAge,24);
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LambdaQueryWrapper<Employee> queryWrapper = Wrappers.<Employee>lambdaQuery()
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.like(StringUtils.isNotEmpty(searchWord), Employee::getUserName,"B")
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.eq(Employee::getGender, 1)
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.gt(Employee::getAge, 24);
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List<Employee> employees = employeeMapper.selectList(queryWrapper);
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```
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@ -82,7 +97,7 @@ List<Employee> employees = employeeMapper.selectList(queryWrapper);
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````java
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EmployeeQuery query = new EmployeeQuery()
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.where.lastName().like("B")
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.where.lastName().like(searchWord, If::notNull)
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.and.gender().eq(1)
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.and.age().gt(24)
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.end();
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@ -96,7 +111,7 @@ List<Employee> employees = employeeMapper.listEntity(query);
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**MyBatis-Flex：**
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````java
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QueryWrapper query = new QueryWrapper()
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QueryWrapper query = QueryWrapper.create()
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.select(
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ACCOUNT.ID,
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ACCOUNT.USER_NAME,
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@ -108,17 +123,16 @@ List<Employee> employees = employeeMapper.selectListByQuery(query);
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**MyBatis-Plus：**
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````java
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QueryWrapper<Employee> queryWrapper = new QueryWrapper<>();
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queryWrapper
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QueryWrapper<Employee> queryWrapper = Wrappers.query()
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.select(
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"id"
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,"user_name"
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,"max(birthday)"
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,"avg(birthday) as sex_avg"
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"id",
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"user_name",
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"max(birthday)",
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"avg(birthday) as sex_avg"
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);
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List<Employee> employees = employeeMapper.selectList(queryWrapper);
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````
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> 缺点：字段硬编码，容易错处。无法使用 ide 的字段进行重构，无法使用 IDE 自动提示，发生错误不能及时发现。
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> 缺点：字段硬编码，容易拼错。无法使用 ide 的字段进行重构，无法使用 IDE 自动提示，发生错误不能及时发现。
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**Fluent-MyBatis：**
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@ -153,16 +167,21 @@ OR (age IN (18,19,20) AND user_name LIKE "%michael%" )
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QueryWrapper query = QueryWrapper.create()
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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).and(ACCOUNT.USER_NAME.like("michael")));
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.or(ACCOUNT.AGE.in(18, 19, 20).and(ACCOUNT.USER_NAME.like("michael")));
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```
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**MyBatis-Plus：**
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```java
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QueryWrapper<Employee> query = new QueryWrapper<>();
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queryWrapper.ge("id",100)
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.and(i->i.eq("sex",1).or(x->x.eq("sex",2)))
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.or(i->i.in("age",{18,19,20}).like("user_name","michael"));
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QueryWrapper<Employee> query = Wrappers.query()
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.ge("id", 100)
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.and(i -> i.eq("sex", 1).or(x -> x.eq("sex", 2)))
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.or(i -> i.in("age", 18, 19, 20).like("user_name", "michael"));
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// or lambda
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LambdaQueryWrapper<Employee> query = Wrappers.<Employee>lambdaQuery()
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.ge(Employee::getId, 100)
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.and(i -> i.eq(Employee::getSex, 1).or(x -> x.eq(Employee::getSex, 2)))
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.or(i -> i.in(Employee::getAge, 18, 19, 20).like(Employee::getUserName, "michael"));
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```
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**Fluent-Mybatis：**
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89
readme_zh.md
89
readme_zh.md
@ -86,9 +86,9 @@ class HelloWorld {
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```java
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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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QueryWrapper query = QueryWrapper.create()
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.select()
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.from(ACCOUNT)
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.from(ACCOUNT) // 单表查询时表名可省略，自动使用Mapper泛型对应的表
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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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@ -96,7 +96,7 @@ QueryWrapper query=QueryWrapper.create()
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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 = mapper.selectListByQuery(query);
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List<Account> accounts = accountMapper.selectListByQuery(query);
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```
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示例3：分页查询
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@ -117,7 +117,7 @@ QueryWrapper query=QueryWrapper.create()
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// AND (user_name LIKE '%张%' OR user_name LIKE '%李%' )
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// ORDER BY `id` DESC
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// LIMIT 40,10
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Page<Account> accounts = mapper.paginate(5,10,query);
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Page<Account> accounts = mapper.paginate(5, 10, query);
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```
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## QueryWrapper 示例
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@ -125,20 +125,30 @@ Page<Account> accounts = mapper.paginate(5,10,query);
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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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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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也可以通过静态方法简写成如下两种形式，效果完全相同：
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```java
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// 方式1
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QueryWrapper query = QueryWrapper.create()
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.select().from(ACCOUNT);
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// 方式2
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QueryWrapper 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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简单示例：
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```java
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QueryWrapper query=new QueryWrapper();
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query.select(ACCOUNT.ID,ACCOUNT.USER_NAME)
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.from(ACCOUNT)
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QueryWrapper query = new QueryWrapper();
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query.select(ACCOUNT.ID, ACCOUNT.USER_NAME)
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.from(ACCOUNT);
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// SQL:
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// SELECT id, user_name
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@ -164,7 +174,7 @@ QueryWrapper query = new QueryWrapper()
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### select functions
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```java
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QueryWrapper query=new QueryWrapper()
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QueryWrapper query = new QueryWrapper()
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.select(
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ACCOUNT.ID,
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ACCOUNT.USER_NAME,
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@ -180,9 +190,10 @@ QueryWrapper query=new QueryWrapper()
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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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Integer num = 100;
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String userName = "michael";
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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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@ -221,6 +232,21 @@ QueryWrapper queryWrapper = QueryWrapper.create()
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// SELECT * FROM tb_account
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// WHERE user_name LIKE ?
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```
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### where 自动忽略 null 值
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当遇到条件值为 null 时，会自动忽略该条件，不会拼接到 SQL 中
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```java
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Integer num = null;
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String userName = "michael";
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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(num))
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.and(ACCOUNT.USER_NAME.like(userName));
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// SQL:
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// SELECT * FROM tb_account
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// WHERE user_name LIKE '%michael%'
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```
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### where select
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@ -262,7 +288,7 @@ QueryWrapper queryWrapper=QueryWrapper.create()
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### and (...) or (...)
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```java
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QueryWrapper queryWrapper=QueryWrapper.create()
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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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@ -279,7 +305,7 @@ QueryWrapper queryWrapper=QueryWrapper.create()
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### group by
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```java
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QueryWrapper queryWrapper=QueryWrapper.create()
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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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@ -292,7 +318,7 @@ QueryWrapper queryWrapper=QueryWrapper.create()
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### having
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```java
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QueryWrapper queryWrapper=QueryWrapper.create()
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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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@ -307,7 +333,7 @@ QueryWrapper queryWrapper=QueryWrapper.create()
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### orderBy
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```java
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QueryWrapper queryWrapper=QueryWrapper.create()
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QueryWrapper queryWrapper = QueryWrapper.create()
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.select()
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.from(ACCOUNT)
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.orderBy(ACCOUNT.AGE.asc()
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@ -321,7 +347,7 @@ QueryWrapper queryWrapper=QueryWrapper.create()
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### join
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```java
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QueryWrapper queryWrapper=QueryWrapper.create()
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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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@ -400,31 +426,31 @@ Db + Row 工具类，提供了在 Entity 实体类之外的数据库操作能力
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```java
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//使用原生 SQL 插入数据
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String sql="insert into tb_account(id,name) value (?, ?)";
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Db.insertBySql(sql,1,"michael");
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Db.insertBySql(sql, 1, "michael");
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//使用 Row 插入数据
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Row account=new Row();
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account.set("id",100);
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account.set("name","Michael");
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Db.insert("tb_account",account);
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Row account = new Row();
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account.set("id", 100);
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account.set("name", "Michael");
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Db.insert("tb_account", account);
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//根据主键查询数据
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Row row=Db.selectOneById("tb_account","id",1);
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Row row = Db.selectOneById("tb_account", "id", 1);
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//Row 可以直接转换为 Entity 实体类，且性能极高
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Account account=row.toEntity(Account.class);
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Account account = row.toEntity(Account.class);
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//查询所有大于 18 岁的用户
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String listsql="select * from tb_account where age > ?"
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List<Row> rows=Db.selectListBySql(sql,18);
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String listsql = "select * from tb_account where age > ?"
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List<Row> rows = Db.selectListBySql(sql, 18);
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//分页查询：每页 10 条数据，查询第 3 页的年龄大于 18 的用户
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QueryWrapper query=QueryWrapper.create()
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QueryWrapper query = QueryWrapper.create()
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.where(ACCOUNT.AGE.ge(18));
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Page<Row> rowPage=Db.paginate("tb_account",3,10,query);
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Page<Row> rowPage = Db.paginate("tb_account", 3, 10, query);
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```
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> Db 工具类还提供了更多 增、删、改、查和分页查询等方法。
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@ -444,7 +470,7 @@ update(T entity)
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有些场景下，我们可能希望只更新 几个 字段，而其中个别字段需要更新为 null。此时需要用到 `UpdateEntity` 工具类，以下是示例代码：
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```java
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Account account=UpdateEntity.of(Account.class);
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Account account = UpdateEntity.of(Account.class);
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account.setId(100);
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account.setUserName(null);
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account.setSex(1);
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@ -466,7 +492,7 @@ set user_name = ?, sex = ? where id = ?
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## 自定义 TypeHandler
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使用 @column 注解：
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使用 @Column 注解：
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```java
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@Table("tb_account")
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@ -488,7 +514,6 @@ public class Account {
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}
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options.put(key, value);
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}
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}
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```
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@ -545,7 +570,7 @@ public class UUIDKeyGenerator implements IKeyGenerator {
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第 2 步：注册 UUIDKeyGenerator
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```java
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KeyGeneratorFactory.register("myUUID",new UUIDKeyGenerator());
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KeyGeneratorFactory.register("myUUID", new UUIDKeyGenerator());
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```
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第 3 步：在 Entity 里使用 "myUUID" 生成器：
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