Caused by: org.hibernate.hql.internal.ast.QuerySyntaxException: User is not mapped

Caused by: org.hibernate.hql.internal.ast.QuerySyntaxException: User is not mapped [SELECT count(u.id) FROM User u WHERE u.platform = :platform AND u.updatedDate <= :updatedDate]
	at org.hibernate.hql.internal.ast.QuerySyntaxException.generateQueryException(QuerySyntaxException.java:79) ~[hibernate-core-5.3.9.Final.jar:5.3.9.Final]
	at org.hibernate.QueryException.wrapWithQueryString(QueryException.java:103) ~[hibernate-core-5.3.9.Final.jar:5.3.9.Final]
	at org.hibernate.hql.internal.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:219) ~[hibernate-core-5.3.9.Final.jar:5.3.9.Final]
	at org.hibernate.hql.internal.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:143) ~[hibernate-core-5.3.9.Final.jar:5.3.9.Final]
	at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:119) ~[hibernate-core-5.3.9.Final.jar:5.3.9.Final]
	at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:80) ~[hibernate-core-5.3.9.Final.jar:5.3.9.Final]
	at org.hibernate.engine.query.spi.QueryPlanCache.getHQLQueryPlan(QueryPlanCache.java:153) ~[hibernate-core-5.3.9.Final.jar:5.3.9.Final]
	at org.hibernate.internal.AbstractSharedSessionContract.getQueryPlan(AbstractSharedSessionContract.java:605) ~[hibernate-core-5.3.9.Final.jar:5.3.9.Final]
	at org.hibernate.internal.AbstractSharedSessionContract.createQuery(AbstractSharedSessionContract.java:714) ~[hibernate-core-5.3.9.Final.jar:5.3.9.Final]
	... 79 common frames omitted

解决办法：

原因是你的SQL写错了。

SELECT count(u.id) FROM user u;

这里的表名不是你数据库的表名，而是你写的类名User

正确做法：

SELECT count(u.id) FROM User u;