我可以将此SQL代码重写为querydsl吗？

Question

我有sql代码，用于计算不同谓词在db中的记录数

    SELECT
    count(*) as total_count,
    count(notAided) as not_aided_count,
    count(chatAided) as chat_aided_count
FROM (
    SELECT
        CASE WHEN aided_with IS NULL THEN 1 END notAided,
        CASE WHEN aided_with = 'CHAT' THEN 1 END chatAided
    FROM sessions
) sessions

我可以用querydsl重写它吗？我看了一下CaseBuilder，但不知道如何在选择查询中使用它

Answer 1

一个人可以写：

query.select(
     QSession.session.id.count().as("total_count"),
     new CaseBuilder().when(QSession.session.aidedWith.isNotNull()).then(1).otherwise(Expressions.<Integer> nullExpression()).count().as("not_aided_count"),
     new CaseBuilder().when(QSession.session.aidedWith.eq("CHAT")).then(1).otherwise(Expressions.<Integer> nullExpression()).count().as("chat_aided_count")
)

与SQL等效：

SELECT
    count(*) as total_count,
    count(CASE WHEN aided_with IS NULL THEN 1 END) as not_aided_count,
    count(CASE WHEN aided_with = 'CHAT' THEN 1 END) as chat_aided_count
FROM sessions