我有一个数据表,其中包含设置和释放列,两者都包含时间戳。我的目标是使用CriteriaQuery创建下面的SQL查询的等效项。
SQL 查询:SELECT TIMESTAMPDIFF(SECOND, setup, released)) as sum_duration FROM calls
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,当我尝试运行此代码时,它抛出了一个异常;似乎文本不是呈现为常量,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}
所以我尝试匿名覆盖 LiteralExpression#render 以直接将我提供的字符串返回给该方法,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:我如何修复我正在尝试做的这个操作,或者实现最初的目标?
我正在使用Hibernate,我的数据库是MySQL。
以下是等效 JPA 标准查询的说明
从 TIMESTAMPDIFF(秒、设置、释放(<3600 的调用中选择 *;
首先,您必须创建单位表达式并将其从将"SECOND"参数作为单位并仅覆盖其rendor(RenderingContext renderingContext)
方法的BasicFunctionExpression
扩展。
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);
它正在工作。
我遇到了同样的问题:SECOND
将被撇号包围,查询将引发异常。
我通过以下代码解决了它:
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
用案例陈述来模拟它。
这是一个比Kalid Shah的解决方案稍微通用的解决方案。
基本上,我们需要的是一个自定义的"不透明文字"Expression
类,它能够通过任意令牌表达式(如MONTH
、YEAR
、INTERVAL 1 DAY
等(作为函数参数传递给MySQL:
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());