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Fluent Mybatis實(shí)際開(kāi)發(fā)中的優(yōu)勢(shì)對(duì)比

 更新時(shí)間:2021年08月04日 15:28:36   作者:夜慬涼  
本文給大家介紹如何通過(guò)IQuery和IUpdate定義強(qiáng)大的動(dòng)態(tài)SQL語(yǔ)句,給大家分享Fluent Mybatis實(shí)際開(kāi)發(fā)中的優(yōu)勢(shì)講解,感興趣的朋友一起看看吧

之前文章介紹過(guò)了Fluent基本框架等,其中有幾個(gè)重要的方法用到了IQuery和IUpdate對(duì)象。 這2個(gè)對(duì)象是FluentMybatis實(shí)現(xiàn)復(fù)雜和動(dòng)態(tài)sql的構(gòu)造類,通過(guò)這2個(gè)對(duì)象fluent mybatis可以不用寫(xiě)具體的xml文件, 直接通過(guò)java api可以構(gòu)造出比較復(fù)雜的業(yè)務(wù)sql語(yǔ)句,做到代碼邏輯和sql邏輯的合一。下面接著介紹如何通過(guò)IQuery和IUpdate定義強(qiáng)大的動(dòng)態(tài)SQL語(yǔ)句。

表結(jié)構(gòu) 假如有學(xué)生成績(jī)表結(jié)構(gòu)如下:

create table `student_score`
(
    id           bigint auto_increment comment '主鍵ID' primary key,
    student_id   bigint            not null comment '學(xué)號(hào)',
    gender_man   tinyint default 0 not null comment '性別, 0:女; 1:男',
    school_term  int               null comment '學(xué)期',
    subject      varchar(30)       null comment '學(xué)科',
    score        int               null comment '成績(jī)',
    gmt_create   datetime          not null comment '記錄創(chuàng)建時(shí)間',
    gmt_modified datetime          not null comment '記錄最后修改時(shí)間',
    is_deleted   tinyint default 0 not null comment '邏輯刪除標(biāo)識(shí)'
) engine = InnoDB default charset=utf8;

統(tǒng)計(jì)2000年到2019年, 三門(mén)學(xué)科(‘英語(yǔ)', ‘?dāng)?shù)學(xué)', ‘語(yǔ)文')分?jǐn)?shù)按學(xué)期,學(xué)科統(tǒng)計(jì)最低分,最高分和平均分,統(tǒng)計(jì)結(jié)果按學(xué)期和學(xué)科排序
SQL:

select school_term, subject, count(score), min(score), max(score), avg(score)
from student_score
where school_term between 2000 and 2019
  and subject in ('英語(yǔ)', '數(shù)學(xué)', '語(yǔ)文')
  and is_deleted = 0
group by school_term, subject
order by school_term, subject
  1. 通過(guò)FluentMybatis來(lái)具體實(shí)現(xiàn)
  2. 在StudentScoreDao類上定義接口
@Data
public 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<StudentScoreEntity> {
    /**
     * 統(tǒng)計(jì)從fromYear到endYear年間學(xué)科subjects的統(tǒng)計(jì)數(shù)據(jù)
     *
     * @param fromYear 統(tǒng)計(jì)年份區(qū)間開(kāi)始
     * @param endYear  統(tǒng)計(jì)年份區(qū)間結(jié)尾
     * @param subjects 統(tǒng)計(jì)的學(xué)科列表
     * @return 統(tǒng)計(jì)數(shù)據(jù)
     */
    List<ScoreStatistics> statistics(int fromYear, int endYear, String[] subjects);
}

在StudentScoreDaoImpl上實(shí)現(xiàn)業(yè)務(wù)邏輯

@Repository
public class StudentScoreDaoImpl extends StudentScoreBaseDao implements StudentScoreDao {
    @Override
    public List<ScoreStatistics> 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()
        );
    }
}
  1. DaoImpl實(shí)現(xiàn)中,除了根據(jù)條件返回統(tǒng)計(jì)結(jié)果,還講結(jié)果按照下劃線轉(zhuǎn)駝峰的規(guī)則自動(dòng)轉(zhuǎn)換為ScoreStatistics對(duì)象返回。
  2. 測(cè)試
@RunWith(SpringRunner.class)
@SpringBootTest(classes = QuickStartApplication.class)
public class StudentScoreDaoImplTest {
    @Autowired
    private StudentScoreDao dao;

    @Test
    public void statistics() {
        List<ScoreStatistics> list = dao.statistics(2000, 2019, new String[]{"語(yǔ)文", "數(shù)學(xué)", "英語(yǔ)"});
        System.out.println(list);
    }
}

查看控制臺(tái)輸出結(jié)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), 語(yǔ)文(String), 數(shù)學(xué)(String), 英語(yǔ)(String)
DEBUG - <==      Total: 30
[ScoreStatistics(schoolTerm=2000, subject=數(shù)學(xué), count=17, minScore=1, maxScore=93, avgScore=36.0588),
 ...
 ScoreStatistics(schoolTerm=2009, subject=語(yǔ)文, count=24, minScore=3, maxScore=100, avgScore=51.2500)]

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