我有一个数据表,其中包含设置和释放列,两者都保存时间戳。我的目标是使用 CriteriaQuery 创建与下面的 SQL 查询等效的内容。
SQL查询:
SELECT TIMESTAMPDIFF(SECOND, setup, released)) as sum_duration FROM calls
CriteriaBuilder#diff()函数显然不起作用,因为它需要数字参数,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,当我尝试运行这段代码时,它抛出了异常;看来文字没有呈现为常量,而是呈现为参数:
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}
因此,我尝试匿名重写 LiteralExpression#render 以直接返回我提供给该方法的字符串,但是出现了此异常。
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:我怎样才能修复我正在尝试做的这个操作,或者达到最初的目标?
我使用的是Hibernate,我的数据库是MySQL。
这里是
的等效 JPA Criteria Query 的解释从 TIMESTAMPDIFF(SECOND, setup,release) 的调用中选择 * < 3600;
首先,您必须创建单位表达式并从
BasicFunctionExpression
扩展它,其中以“SECOND”参数作为单位并仅覆盖其 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();
}
}
然后您可以在 JPA 标准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);
它正在工作。
我遇到了同样的问题:
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();
这给了我同样的结果。
CASE WHEN 1=1 THEN TIMESTAMPDIFF(SECOND,startDatetime,endDatetime) ELSE 0 END
用 case 语句模拟它。
这是一个比 Kalid Shah 的解决方案稍微更通用的解决方案。
基本上,我们需要的是一个自定义的“不透明文字”
Expression
类,它能够将任意标记表达式(如MONTH
、YEAR
、INTERVAL 1 DAY
等)传递给MySQL作为函数参数:
import javax.persistence.criteria.CriteriaBuilder;
import org.hibernate.query.criteria.internal.CriteriaBuilderImpl;
import org.hibernate.query.criteria.internal.compile.RenderingContext;
import org.hibernate.query.criteria.internal.expression.LiteralExpression;
/**
* Represents an opaque literal that gets pass through JPA unaltered into SQL.
*/
@SuppressWarnings("serial")
public class OpaqueLiteralExpression extends LiteralExpression<Void> {
private final String value;
public OpaqueLiteralExpression(CriteriaBuilderImpl builder, String value) {
super(builder, Void.class, null);
if (value == null)
throw new IllegalArgumentException("null value");
this.value = value;
}
// ExpressionImpl
@Override
public String render(RenderingContext renderingContext) {
return this.value;
}
}
然后你可以像这样使用它:
final Expression<LocalDate> birthDate = student.get(Student_.birthDate);
final Expression<Integer> age = builder.function("TIMESTAMPDIFF", Integer.class,
new OpaqueLiteralExpression(builder, "YEAR"), birthDate, LocalDate.now());
我在这里遇到了一个类似的问题,但有一个变体 - Hibernate 6 已经发生了足够的变化,以至于“OpaqueLiteralExpression”答案建议的内部 API 不再适用。
我设法使用原始休眠标准构建器解决了这个问题
cb as HibernateCriteriaBuilder
val duration = cb.durationBetween(startTime, endTime)
val overlap = cb.greaterThanOrEqualTo(cb.durationByUnit(TemporalUnit.MINUTE, duration), 10)