how to use querydsl instead of SQL

Question

Recently, I wrote a program which is connection database!

I think that replace sql to querydsl;

For example SQL:

SELECT"MAX"(aa) AS big,"MIN"(aa) AS small FROM (
SELECT
    "TO_NUMBER"(MONITOR_INFO."VALUE") aa
FROM
    MONITOR_INFO
WHERE
    MONITOR_INFO.DSID IN (9211)
AND MONITOR_INFO."TIME" BETWEEN "TO_DATE" (
    '2013-09-03 00:00:00',
    'yyyy-mm-dd hh24:mi:ss'
)
AND TO_DATE (
    '2013-09-04 00:00:00',
    'yyyy-mm-dd hh24:mi:ss'
)
)

How can I use Querydsl to replace?

Timo Westkämper · Accepted Answer · 2013-09-16 10:23:59Z

1

Let's assume you are using Querydsl SQL and you have generated your metamodel for Querydsl. Then you could describe the given query as

QMonitorInfo monitorInfo = QMonitorInfo.monitorInfo;
List<Tuple> result = query.from(monitorInfo)
      .where(
         monitorInfo.dsid.eq(9211),
         monitorInfo.time.between(start, end))
      .list(monitorInfo.value.castToNum(Integer.class).max(), 
            monitorInfo.value.castToNum(Integer.class).min());

answered Sep 16, 2013 at 10:23

Timo Westkämper

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2 Comments

boy Over a year ago

Thank you for your answer. But your information is similer to List<Tuple> result = query.from(monitorInfo).where(monitorInfo.dsid.eq(9211)).where(monitorInfo.time.between(start, end)).uniqueResult(monitorInfo.value.castToNum(Integer.class).max(),monitorInfo.value.castToNum(Integer.class).min()); with two method ,I get the return data is null. why I use nest SQL ? because monitorInfo.value isn't number ,it's varchar.

Timo Westkämper Over a year ago

Are you using Querydsl with JPA or SQL? Do you get null or an empty list or a list with null as the only entry?

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