一文掌握MyBatis Plus的条件构造器方法

@Test
void contextLoads() {
    // 查询用户名包含a，年龄在 10 - 20 之间并且邮箱不为空的用户
    QueryWrapper<User> wrapper = new QueryWrapper<>();
    wrapper.like("name","a")
            .between("age",10,20)
            .isNotNull("email");
    List<User> users = userMapper.selectList(wrapper);
    users.forEach(System.out::println);
}

==>  Preparing: SELECT id,name,age,email,is_delete FROM user WHERE is_delete=0 AND (name LIKE ? AND age BETWEEN ? AND ? AND email IS NOT NULL)
==> Parameters: %a%(String), 10(Integer), 20(Integer)
<==    Columns: id, name, age, email, is_delete
<==        Row: 2, dada, 11, 111@qq.com, 0
<==        Row: 4, dahe, 12, 34567@qq.com, 0
<==      Total: 2

@Test
void contextLoads() {
    // 查询用户信息，按照年龄的降序排序，若年龄相同，则按照id升序排序
    QueryWrapper<User> wrapper = new QueryWrapper<>();
    wrapper.orderByDesc("age").orderByAsc("id");
    List<User> users = userMapper.selectList(wrapper);
    users.forEach(System.out::println);
}

==>  Preparing: SELECT id,name,age,email,is_delete FROM user WHERE is_delete=0 ORDER BY age DESC,id ASC
==> Parameters: 
<==    Columns: id, name, age, email, is_delete
<==        Row: 3, dahe, 33, 34567@qq.com, 0
<==        Row: 4, dahe, 12, 34567@qq.com, 0
<==        Row: 2, dada, 11, 111@qq.com, 0
<==      Total: 3

@Test
void contextLoads() {
    // 将用户名中包含有a并且（年龄大于20或邮箱为null）的用户信息查询出来
    QueryWrapper<User> wrapper = new QueryWrapper<>();
    wrapper.like("name", "a")
            .and(i -> i.gt("age", 20).or().isNull("email"));
    List<User> users = userMapper.selectList(wrapper);
    users.forEach(System.out::println);
}

==>  Preparing: SELECT id,name,age,email,is_delete FROM user WHERE is_delete=0 AND (name LIKE ? AND (age > ? OR email IS NULL))
==> Parameters: %a%(String), 20(Integer)
<==    Columns: id, name, age, email, is_delete
<==        Row: 3, dahe, 33, 34567@qq.com, 0
<==      Total: 1

@Test
void contextLoads() {
    QueryWrapper<User> wrapper = new QueryWrapper<>();
    wrapper.select("name","email");
    List<Map<String, Object>> maps = userMapper.selectMaps(wrapper);
    maps.forEach(System.out::println);
}

==>  Preparing: SELECT name,email FROM user WHERE is_delete=0
==> Parameters: 
<==    Columns: name, email
<==        Row: dada, 111@qq.com
<==        Row: dahe, 34567@qq.com
<==        Row: dahe, 34567@qq.com
<==      Total: 3
Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@237add]
{name=dada, email=111@qq.com}
{name=dahe, email=34567@qq.com}
{name=dahe, email=34567@qq.com}

@Test
void contextLoads() {
    QueryWrapper<User> wrapper = new QueryWrapper<>();
    wrapper.inSql("id","select id from user where id > 1");
    List<User> users = userMapper.selectList(wrapper);
    users.forEach(System.out::println);
}

==>  Preparing: SELECT id,name,age,email,is_delete FROM user WHERE is_delete=0 AND (id IN (select id from user where id > 1))
==> Parameters: 
<==    Columns: id, name, age, email, is_delete
<==        Row: 2, dada, 11, 111@qq.com, 0
<==        Row: 3, dahe, 33, 34567@qq.com, 0
<==        Row: 4, dahe, 12, 34567@qq.com, 0
<==      Total: 3

@Test
void contextLoads() {
    // 将名字中包含a的记录修改
    UpdateWrapper<User> wrapper = new UpdateWrapper<>();
    wrapper.like("name","a");
    wrapper.set("name","hello").set("age",18);
    userMapper.update(null, wrapper);
}

JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@36c07c75] will not be managed by Spring
==>  Preparing: UPDATE user SET name=?,age=? WHERE is_delete=0 AND (name LIKE ?)
==> Parameters: hello(String), 18(Integer), %a%(String)
<==    Updates: 3

@Test
 void contextLoads() {
     String name = null;
     Integer ageBegin = 18;
     Integer ageEnd = 28;
     QueryWrapper<User> wrapper = new QueryWrapper<>();
     if (StringUtils.isNotBlank(name)) {
         wrapper.like("name", name);
     }
     if (ageBegin != null) {
         wrapper.ge("age", ageBegin);
     }
     if (ageEnd != null) {
         wrapper.le("age", ageEnd);
     }
     List<User> users = userMapper.selectList(wrapper);
     users.forEach(System.out::println);
 }

==>  Preparing: SELECT id,name,age,email,is_delete FROM user WHERE is_delete=0 AND (age >= ? AND age <= ?)
==> Parameters: 18(Integer), 28(Integer)
<==    Columns: id, name, age, email, is_delete
<==        Row: 3, hello, 18, 34567@qq.com, 0
<==        Row: 4, hello, 18, 34567@qq.com, 0
<==      Total: 2

@Test
void contextLoads() {
    String name = null;
    Integer ageBegin = 18;
    Integer ageEnd = 28;
    QueryWrapper<User> wrapper = new QueryWrapper<>();
    wrapper.like(StringUtils.isNotBlank(name), "name", name);
    wrapper.ge(ageBegin != null, "age", ageBegin);
    wrapper.le(ageEnd != null, "age", ageEnd);
    List<User> users = userMapper.selectList(wrapper);
    users.forEach(System.out::println);
}

==>  Preparing: SELECT id,name,age,email,is_delete FROM user WHERE is_delete=0 AND (age >= ? AND age <= ?)
==> Parameters: 18(Integer), 28(Integer)
<==    Columns: id, name, age, email, is_delete
<==        Row: 3, hello, 18, 34567@qq.com, 0
<==        Row: 4, hello, 18, 34567@qq.com, 0
<==      Total: 2

@Test
 void contextLoads() {
     String name = null;
     Integer ageBegin = 18;
     Integer ageEnd = 28;
     LambdaQueryWrapper<User> wrapper = new LambdaQueryWrapper<>();
     wrapper.like(StringUtils.isNotBlank(name), User::getName, name);
     wrapper.ge(ageBegin != null, User::getAge, ageBegin);
     wrapper.le(ageEnd != null, User::getAge, ageEnd);
     List<User> users = userMapper.selectList(wrapper);
     users.forEach(System.out::println);
 }

==>  Preparing: SELECT id,name,age,email,is_delete FROM user WHERE is_delete=0 AND (age >= ? AND age <= ?)
==> Parameters: 18(Integer), 28(Integer)
<==    Columns: id, name, age, email, is_delete
<==        Row: 3, hello, 18, 34567@qq.com, 0
<==        Row: 4, hello, 18, 34567@qq.com, 0
<==      Total: 2