Fluent|Fluent Mybatis实际开发中的优势对比 FluentMybatis实际开发中的优势对

【Fluent|Fluent Mybatis实际开发中的优势对比】之前文章介绍过了Fluent基本框架等，其中有几个重要的方法用到了IQuery和IUpdate对象。这2个对象是FluentMybatis实现复杂和动态sql的构造类，通过这2个对象fluent mybatis可以不用写具体的xml文件，直接通过java api可以构造出比较复杂的业务sql语句，做到代码逻辑和sql逻辑的合一。下面接着介绍如何通过IQuery和IUpdate定义强大的动态SQL语句。
表结构假如有学生成绩表结构如下:

create table `student_score`(idbigint auto_increment comment '主键ID' primary key,student_idbigintnot null comment '学号',gender_mantinyint default 0 not null comment '性别, 0:女; 1:男',school_termintnull comment '学期',subjectvarchar(30)null comment '学科',scoreintnull comment '成绩',gmt_createdatetimenot null comment '记录创建时间',gmt_modified datetimenot null comment '记录最后修改时间',is_deletedtinyint default 0 not null comment '逻辑删除标识') engine = InnoDB default charset=utf8;

统计2000年到2019年, 三门学科(‘英语', ‘数学', ‘语文')分数按学期,学科统计最低分，最高分和平均分,统计结果按学期和学科排序
SQL：

select school_term, subject, count(score), min(score), max(score), avg(score)from student_scorewhere school_term between 2000 and 2019and subject in ('英语', '数学', '语文')and is_deleted = 0group by school_term, subjectorder by school_term, subject

通过FluentMybatis来具体实现
在StudentScoreDao类上定义接口

@Datapublic class ScoreStatistics {private int schoolTerm; private String subject; private long count; private Integer minScore; private Integer maxScore; private BigDecimal avgScore; }

public interface StudentScoreDao extends IBaseDao {/*** 统计从fromYear到endYear年间学科subjects的统计数据** @param fromYear 统计年份区间开始* @param endYear统计年份区间结尾* @param subjects 统计的学科列表* @return 统计数据*/List statistics(int fromYear, int endYear, String[] subjects); }

在StudentScoreDaoImpl上实现业务逻辑

@Repositorypublic class StudentScoreDaoImpl extends StudentScoreBaseDao implements StudentScoreDao {@Overridepublic List statistics(int fromSchoolTerm, int endSchoolTerm, String[] subjects) {return super.listPoJos(ScoreStatistics.class, super.query().select.schoolTerm().subject().count("count").min.score("min_score").max.score("max_score").avg.score("avg_score").end().where.isDeleted().isFalse().and.schoolTerm().between(fromSchoolTerm, endSchoolTerm).and.subject().in(subjects).end().groupBy.schoolTerm().subject().end().orderBy.schoolTerm().asc().subject().asc().end()); }}

DaoImpl实现中，除了根据条件返回统计结果，还讲结果按照下划线转驼峰的规则自动转换为ScoreStatistics对象返回。
测试

@RunWith(SpringRunner.class)@SpringBootTest(classes = QuickStartApplication.class)public class StudentScoreDaoImplTest {@Autowiredprivate StudentScoreDao dao; @Testpublic void statistics() {List list = dao.statistics(2000, 2019, new String[]{"语文", "数学", "英语"}); System.out.println(list); }}

查看控制台输出结果：

DEBUG - ==>Preparing: SELECT school_term, subject, count(*) AS count, MIN(score) AS min_score, MAX(score) AS max_score, AVG(score) AS avg_score
FROM student_score
WHERE is_deleted = ?
AND school_term BETWEEN ? AND ?
AND subject IN (?, ?, ?)
GROUP BY school_term, subject
ORDER BY school_term ASC, subject ASC
DEBUG - ==> Parameters: false(Boolean), 2000(Integer), 2019(Integer), 语文(String), 数学(String), 英语(String)
DEBUG - <==Total: 30
[ScoreStatistics(schoolTerm=2000, subject=数学, count=17, minScore=1, maxScore=93, avgScore=36.0588),
...
ScoreStatistics(schoolTerm=2009, subject=语文, count=24, minScore=3, maxScore=100, avgScore=51.2500)]

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