12장 조인 - case문

1) 단순한 조건

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

        for (String s : result) {
            System.out.println("s = " + s);
        }
    }

2) 복잡한 조건

    @Test
    public void complexCase(){
        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();

        for (String s : result) {
            System.out.println("s = " + s);
        }
    }

3) orderBy에서 Case 문 함께 사용하기 예제

NumberExpression<Integer> rankPath = new CaseBuilder()
 .when(member.age.between(0, 20)).then(2)
 .when(member.age.between(21, 30)).then(1)
 .otherwise(3);
List<Tuple> result = queryFactory
 .select(member.username, member.age, rankPath)
 .from(member)
 .orderBy(rankPath.desc())
 .fetch();
for (Tuple tuple : result) {
 String username = tuple.get(member.username);
 Integer age = tuple.get(member.age);
 Integer rank = tuple.get(rankPath);
 System.out.println("username = " + username + " age = " + age + " rank = "
+ rank);
}