我一直在使用mariaDB,现在我正在转向postgres。 我在JPA中有一个查询
select count(<primarykeycolumn>) from tablename where condition
但是Postgres给出了一个错误,说明需要group by
条款。
我不想添加组,代码已启动并与mariaDB一起运行。
以下是错误:
Internal Exception: org.postgresql.util.PSQLException: ERROR: column "app_movie_summary.creationdate" must appear in the GROUP BY clause or be used in an aggregate function
Position: 55
Error Code: 0
Call: SELECT COUNT(id) FROM mytable ORDER BY CREATIONDATE DESC
Query: ReportQuery(name="App_Movie_Summary.findAllByCreationDateCount" referenceClass=App_Movie_Summary sql="SELECT COUNT(Id) FROM mytable ORDER BY CREATIONDATE DESC")
at org.eclipse.persistence.exceptions.DatabaseException.sqlException(DatabaseException.java:340)
at org.eclipse.persistence.internal.databaseaccess.DatabaseAccessor.basicExecuteCall(DatabaseAccessor.java:684)
at org.eclipse.persistence.internal.databaseaccess.DatabaseAccessor.executeCall(DatabaseAccessor.java:560)
at org.eclipse.persistence.internal.sessions.AbstractSession.basicExecuteCall(AbstractSession.java:2055)
at org.eclipse.persistence.sessions.server.ServerSession.executeCall(ServerSession.java:570)
at org.eclipse.persistence.internal.queries.DatasourceCallQueryMechanism.executeCall(DatasourceCallQueryMechanism.java:242)
at org.eclipse.persistence.internal.queries.DatasourceCallQueryMechanism.executeCall(DatasourceCallQueryMechanism.java:228)
at org.eclipse.persistence.internal.queries.DatasourceCallQueryMechanism.executeSelectCall(DatasourceCallQueryMechanism.java:299)
at org.eclipse.persistence.internal.queries.DatasourceCallQueryMechanism.selectAllRows(DatasourceCallQueryMechanism.java:694)
at org.eclipse.persistence.internal.queries.ExpressionQueryMechanism.selectAllRowsFromTable(ExpressionQueryMechanism.java:2740)
at org.eclipse.persistence.internal.queries.ExpressionQueryMechanism.selectAllReportQueryRows(ExpressionQueryMechanism.java:2677)
at org.eclipse.persistence.queries.ReportQuery.executeDatabaseQuery(ReportQuery.java:852)
at org.eclipse.persistence.queries.DatabaseQuery.execute(DatabaseQuery.java:904)
at org.eclipse.persistence.queries.ObjectLevelReadQuery.execute(ObjectLevelReadQuery.java:1134)
at org.eclipse.persistence.queries.ReadAllQuery.execute(ReadAllQuery.java:460)
at org.eclipse.persistence.queries.ObjectLevelReadQuery.executeInUnitOfWork(ObjectLevelReadQuery.java:1222)
at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.internalExecuteQuery(UnitOfWorkImpl.java:2896)
at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1857)
at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1839)
at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1804)
at org.eclipse.persistence.internal.jpa.QueryImpl.executeReadQuery(QueryImpl.java:258)
at org.eclipse.persistence.internal.jpa.QueryImpl.getSingleResult(QueryImpl.java:521)
at org.eclipse.persistence.internal.jpa.EJBQueryImpl.getSingleResult(EJBQueryImpl.java:400)
答案 0 :(得分:0)
在PostgreSQL中,除非count
未聚合列,否则不能将聚合函数(如creationdates
)与非聚合列(GROUP BY
)混合使用。在这种情况下,看起来你不需要分组,因为你不需要ORDER BY creationdate
。订单与count(*)
无关。此查询完全有效:
SELECT count(*) FROM mytable
如果您确实需要creationdate
,则必须 GROUP BY
。当你这样做时,ORDER BY
也有意义:
SELECT creationdate, count(*) from mytable
GROUP BY creationdate
ORDER BY creationdate