使用TIMESTAMPDIFF和JPA条件查询并使用hibernate作为提供程序-Java 学习之路

我有一个包含列设置和释放的数据表，两者都有时间戳 . 我的目标是使用CriteriaQuery在下面创建一个等价的SQL查询 .

SQL查询： SELECT TIMESTAMPDIFF(SECOND, setup, released)) as sum_duration FROM calls

CriteriaBuilder#diff()函数显然不起作用，因为它需要参数是Numbers，所以我尝试使用CriteriaBuilder#function：

EntityManager entityManager = emProvider.get();

CriteriaBuilder criteriaBuilder = entityManager.getCriteriaBuilder();

CriteriaQuery<Integer> query = criteriaBuilder.createQuery();

Root<Thingy> thingyRoot = query.from(Thingy.class);

Path<DateTime> setup = root.get("setup");
Path<DateTime> release = root.get("release");

Expression secondLiteral = criteriaBuilder.literal("SECOND");

Expression func = criteriaBuilder.function("TIMESTAMPDIFF", Integer.class, secondLiteral, setup, release);

entityManager.createQuery(query).getResultList();

但是，当我尝试运行此代码时，它抛出异常;似乎文字不是作为常量呈现，而是作为参数呈现：

java.lang.IllegalStateException: No data type for node: org.hibernate.hql.internal.ast.tree.MethodNode 
 \-[METHOD_CALL] MethodNode: '('
    +-[METHOD_NAME] IdentNode: 'TIMESTAMPDIFF' {originalText=TIMESTAMPDIFF}
    \-[EXPR_LIST] SqlNode: 'exprList'
       +-[NAMED_PARAM] ParameterNode: '?' {name=param0, expectedType=null}
       +-[DOT] DotNode: 'cdr0_.setup' {propertyName=setup,dereferenceType=ALL,propertyPath=setup,path=generatedAlias0.setup,tableAlias=cdr0_,className=com.vtsl.domain.CDR,classAlias=generatedAlias0}
       |  +-[ALIAS_REF] IdentNode: 'cdr0_.id' {alias=generatedAlias0, className=com.vtsl.domain.CDR, tableAlias=cdr0_}
       |  \-[IDENT] IdentNode: 'setup' {originalText=setup}
       \-[DOT] DotNode: 'cdr0_.release' {propertyName=release,dereferenceType=ALL,propertyPath=release,path=generatedAlias0.release,tableAlias=cdr0_,className=com.vtsl.domain.CDR,classAlias=generatedAlias0}
          +-[ALIAS_REF] IdentNode: 'cdr0_.id' {alias=generatedAlias0, className=com.vtsl.domain.CDR, tableAlias=cdr0_}
          \-[IDENT] IdentNode: 'release' {originalText=release}

所以我试图匿名覆盖LiteralExpression#render直接返回我提供给该方法的字符串，但是这个例外 .

java.lang.IllegalStateException: No data type for node: org.hibernate.hql.internal.ast.tree.MethodNode 
 \-[METHOD_CALL] MethodNode: '('
    +-[METHOD_NAME] IdentNode: 'TIMESTAMPDIFF' {originalText=TIMESTAMPDIFF}
    \-[EXPR_LIST] SqlNode: 'exprList'
       +-[IDENT] IdentNode: 'SECOND' {originalText=SECOND}
       +-[DOT] DotNode: 'cdr0_.setup' {propertyName=setup,dereferenceType=ALL,propertyPath=setup,path=generatedAlias0.setup,tableAlias=cdr0_,className=com.vtsl.domain.CDR,classAlias=generatedAlias0}
       |  +-[ALIAS_REF] IdentNode: 'cdr0_.id' {alias=generatedAlias0, className=com.vtsl.domain.CDR, tableAlias=cdr0_}
       |  \-[IDENT] IdentNode: 'setup' {originalText=setup}
       \-[DOT] DotNode: 'cdr0_.release' {propertyName=release,dereferenceType=ALL,propertyPath=release,path=generatedAlias0.release,tableAlias=cdr0_,className=com.vtsl.domain.CDR,classAlias=generatedAlias0}
          +-[ALIAS_REF] IdentNode: 'cdr0_.id' {alias=generatedAlias0, className=com.vtsl.domain.CDR, tableAlias=cdr0_}
          \-[IDENT] IdentNode: 'release' {originalText=release}

所以问题是：我如何修复我正在尝试的操作，或者实现最初的目标？

我正在使用Hibernate，我的数据库是MySQL .

3 回答

我碰到了同样的问题： SECOND 将被撇号包围，查询将抛出异常 .

我通过以下代码解决了这个问题：

CriteriaBuilder builder = em.getCriteriaBuilder();
CriteriaQuery<MyEntity> cq = builder.createQuery( MyEntity.class );
Root<MyEntity> root = cq.from( MyEntity.class );

javax.persistence.criteria.Expression<java.sql.Time> timeDiff = builder.function(
            "TIMEDIFF",
            java.sql.Time.class,
            root.<Date>get( "endDate" ),
            root.<Date>get( "startDate" ) );
javax.persistence.criteria.Expression<Integer> timeToSec = builder.function(
            "TIME_TO_SEC",
            Integer.class,
            timeDiff );

//lessThanOrEqualTo 60 minutes
cq.where( builder.lessThanOrEqualTo( timeToSec, 3600 ) );

return em.createQuery( cq ).getResultList();

这给了我相同的结果 .

回复于 2024-04-27T01:34:35+08:00

这是对等效JPA标准查询的解释

来自TIMESTAMPDIFF（SECOND，设置，发布）<3600的呼叫的SELECT *;

首先，您必须创建单位表达式并从 BasicFunctionExpression 扩展它，以"SECOND"参数为单位，并仅覆盖其 rendor(RenderingContext renderingContext) 方法 .

import java.io.Serializable;
import org.hibernate.query.criteria.internal.CriteriaBuilderImpl;
import org.hibernate.query.criteria.internal.compile.RenderingContext;
import org.hibernate.query.criteria.internal.expression.function.BasicFunctionExpression;

public class UnitExpression extends BasicFunctionExpression<String> implements Serializable {

  public UnitExpression(CriteriaBuilderImpl criteriaBuilder, Class<String> javaType,
      String functionName) {
    super(criteriaBuilder, javaType, functionName);
  }

  @Override
  public String render(RenderingContext renderingContext) {
    return getFunctionName();
  }
}

然后在JPA条件查询中使用此单位表达式 .

EntityManager entityManager = emProvider.get();
CriteriaBuilder criteriaBuilder = entityManager.getCriteriaBuilder();
Root<Calls> thingyRoot = query.from(Calls.class);

    Expression<String> second = new UnitExpression(null, String.class, "SECOND");
    Expression<Integer> timeInSec = cb.function(
        "TIMESTAMPDIFF",
        Integer.class,
        second ,
        root.<Timestamp>get("setup"),
        root.<Timestamp>get("release"));
    List<Predicate> conditions = new ArrayList<>();
    conditions.add(cb.lessThan(timeInSec, 3600));
    cq.where(conditions.toArray(new Predicate[]{}));
    return session.createQuery(cq);

这是工作 .

回复于 2024-04-27T01:34:35+08:00

CASE WHEN 1=1 THEN TIMESTAMPDIFF(SECOND,startDatetime,endDatetime) ELSE 0 END

用案例陈述嘲笑它 .

回复于 2024-04-27T01:34:35+08:00

使用TIMESTAMPDIFF和JPA条件查询并使用hibernate作为提供程序

3 回答

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