3. 掌握在LambdaQueryWrapper中进行求和(sum)操作的方法 MyBatis-Plus本身并不直接提供在LambdaQueryWrapper中进行求和操作的方法,但你可以通过调用select方法来选择需要求和的字段,并在后续的查询中使用MyBatis的聚合函数来实现求和。 4. 结合分组和求和操作,编写LambdaQueryWrapper查询语句 下面是一个完整的示例,展示了如何...
5、【分组、排序:(group、having、order)】 groupBy(R... columns); // 等价于 GROUP BY 字段, ..., 例: groupBy("id", "name") ---> group by id,nameorderByAsc(R... columns); // 等价于 ORDER BY 字段, ... ASC, 例: orderByAsc("id", "name") ---> order by id ASC,name AS...
SUM(m.home_goal + m.away_goal) AS total_goals, SUM(m.home_goal + m.away_goal) - (SELECT AVG(goals) FROM (SELECT EXTRACT(MONTH FROM date) AS month, SUM(home_goal + away_goal) AS goals FROM match GROUP BY month)) AS avg_diff FROM match AS m GROUP BY month; 1. 2. 3. 4...
例: like("name", "媳妇") ---> name like '%媳妇%'notLike(R column, Object val); // 等价于 NOT LIKE '%值%'，例: notLike("name", "媳妇") -
public void selectByGroupAndCount() { // 1. 创建条件对象 QueryWrapper<User> userQueryWrapper = new QueryWrapper<>(); // 这里不用Lambda的原因是查询结果有一个不属于实体类 // 2. 设置条件 userQueryWrapper.select("gender", "count(*) as sum"); ...
name ASC orderByDesc(R... columns); // 等价于 ORDER BY 字段, ... DESC, 例: orderByDesc("id", "name") ---> order by id DESC,name DESC having(String sqlHaving, Object... params); // 等价于 HAVING ( sql语句 ), 例: having("sum(age) > {0}", 11) ---> having sum(age...
orderByDesc(R... columns); // 等价于 ORDER BY 字段, ... DESC, 例: orderByDesc("id", "name") ---> order by id DESC,name DESC having(String sqlHaving, Object... params); // 等价于 HAVING ( sql语句 ), 例: having("sum(age) > {0}", 11) ---> having sum(age) > 11 ...
例: orderByDesc("id", "name") ---> order by id DESC,name DESC having(String sqlHaving, Object... params);// 等价于 HAVING ( sql语句 ), 例: having("sum(age) > {0}", 11) ---> having sum(age) > 11 实现的java代码参考如下通过分组来查询分页的使用代码 ...
orderByDesc(R... columns); // 等价于 ORDER BY 字段, ... DESC, 例: orderByDesc("id", "name") ---> order by id DESC,name DESC having(String sqlHaving, Object... params); // 等价于 HAVING ( sql语句 ), 例: having("sum(age) > {0}", 11) ---> having sum(age) > 11 ...
orderByDesc(R... columns); // 等价于 ORDER BY 字段, ... DESC, 例: orderByDesc("id", "name") ---> order by id DESC,name DESC having(String sqlHaving, Object... params); // 等价于 HAVING ( sql语句 ), 例: having("sum(age) > {0}", 11) ---> having sum(age) > 11 ...