jpa、querydsl常用查询以及对照sql

项目源码

一、动态条件查询

平时使用最多的场景，根据传入的条件动态拼接查询，类似mybatis中的if标签。根据条件判断是否添加条件查询，添加exist子句查询，根据关键字模糊查询id和关键字等。如下所示：

public Predicate buildPredicate() {
    QWxUser qWxUser = QWxUser.wxUser;
    QUserTag qUserTag = QUserTag.userTag;
    QTag qTag = QTag.tag;
    BooleanBuilder predicate = new BooleanBuilder();
    if (StrUtil.isNotBlank(appId)) {
        predicate.and(qWxUser.appId.eq(appId));
    }
    if (StrUtil.isNotBlank(keyword)) {
        String fuzzKeyword = "%" + keyword + "%";
        predicate.and(qWxUser.wxUserId.stringValue().like(fuzzKeyword).or(qWxUser.nickname.like(fuzzKeyword)));
    }
    if (StrUtil.isNotBlank(openId)) {
        predicate.and(qWxUser.openId.eq(openId));
    }
    if (StrUtil.isNotBlank(unionId)) {
        predicate.and(qWxUser.unionId.eq(unionId));
    }
    Optional.ofNullable(status).ifPresent(status -> predicate.and(qWxUser.status.eq(status)));
    Optional.ofNullable(subscribeStartTime).ifPresent(subscribeStartTime ->
            predicate.and(qWxUser.subscribeTime.gt(subscribeStartTime.atStartOfDay(BEIJING_ZONE).toEpochSecond())));
    Optional.ofNullable(subscribeEndTime).ifPresent(subscribeEndTime ->
            predicate.and(qWxUser.subscribeTime.lt(subscribeEndTime.plusDays(1).atStartOfDay(BEIJING_ZONE).toEpochSecond())));
    Optional.ofNullable(subscribe).ifPresent(subscribe -> predicate.and(qWxUser.subscribe.eq(subscribe)));

    Optional.ofNullable(tagId).ifPresent(tagId ->
            predicate.and(JPAExpressions.selectFrom(qUserTag)
                    .where(qWxUser.wxUserId.eq(qUserTag.wxUserId).and(qUserTag.tagId.eq(tagId))).exists()));

    return predicate;
}

public List list(WxUserVO vo) {
    QWxUser qWxUser = QWxUser.wxUser;
    PageRequest pageRequest = vo.toPageRequest();
    List fetch = jpaQueryFactory.selectFrom(qWxUser).where(vo.buildPredicate())
            .offset(pageRequest.getOffset())
            .limit(pageRequest.getPageSize())
            .orderBy(qWxUser.createTime.asc()).fetch();
    return fetch;
}

对应的原生SQL如下：

SELECT *
FROM wx_user u
WHERE u.app_id = '1111111'
AND (cast(u.wx_user_id AS CHAR) LIKE '张三' OR u.nickname LIKE '张三')
AND u.open_id = 'openid11111'
AND u. STATUS = 0
AND u.subscribe_time > 1586069773
AND u.subscribe_time < 1586269773
AND u.subscribe = 1
AND (
    EXISTS (
        SELECT 1
        FROM wx_user_tag ut
        WHERE u.wx_user_id = ut.wx_user_id AND ut.tag_id = 1
    )
)
ORDER BY u.create_time ASC
LIMIT 0, 20

二、多表关联查询

多表关联查询也是比较常用的查询，如下所示：

public List listByWxUserId(Long wxUserId) {
    QTag qTag = QTag.tag;
    QUserTag qUserTag = QUserTag.userTag;
    List list = jpaQueryFactory.selectFrom(qTag)
            .innerJoin(qUserTag).on(qTag.tagId.eq(qUserTag.tagId))
            .where(qUserTag.wxUserId.eq(wxUserId)).fetch();
    return list;
}

对应的原生SQL如下：

select * 
from wx_tag t 
inner join wx_user_tag ut on (t.tag_id=ut.tag_id)
where ut.wx_user_id= 1

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