querydsl case문

Case

• 조건에 따른 값을 지정해주는 문법
• select, where, order by 절에서 사용 가능

simple case

List<String> result = queryFactory
    .select(member.age
        .when(10).then("열살")
        .when(20).then("스무살")
        .otherwise("기타"))
    .from(member)
    .fetch();

complex case

 List<String> result = queryFactory
    .select(
        new CaseBuilder()
            .when(member.age.between(0, 20)).then("0 ~ 20살")
            .when(member.age.between(21, 30)).then("21 ~ 30살")
            .otherwise("기타")
    )
    .from(member)
    .fetch();

With orderBy

NumberExpression<Integer> ageCase = new CaseBuilder()
    .when(member.age.between(0, 20)).then(0)
    .when(member.age.between(21, 30)).then(1)
    .otherwise(2);

 List<Tuple> fetch = queryFactory
    .select(member.username, member.age, ageCase)
    .from(member)
    .orderBy(ageCase.desc())
    .fetch();

• 위와 같이 복잡한 케이스를 변수로 선언하여 select, orderBy절에서 사용할 수 있다.

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참고: 실전! Querydsl - Case문