SQL 带有复合主键查询的 JPA COUNT 不起作用
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JPA COUNT with composite primary key query not working
提问by victorio
In my db, I have a table (Defaults), and when I generate an entity from table, I get these two classes:
在我的数据库中，我有一个表（默认值），当我从表中生成一个实体时，我得到了这两个类：
@Entity
public class Defaults implements Serializable {
private static final long serialVersionUID = 1L;
@EmbeddedId
protected DefaultsPK DefaultsPK;
@Column(name = "ERTEK")
private String ertek;
getter/setter...
}
@Embeddable
public class DefaultsPK implements Serializable {
@Basic(optional = false)
@Column(name = "VALUE_1")
private String value1;
@Basic(optional = false)
@Column(name = "TYPE")
private String type;
@Basic(optional = false)
@Column(name = "VALID_FROM")
@Temporal(TemporalType.TIMESTAMP)
private Date validFrom;
@Basic(optional = false)
@Column(name = "VALID_TO")
@Temporal(TemporalType.TIMESTAMP)
private Date validTo;
getter/setter...
}
That is why becaues the primary key is including the values. I want to count all the rows in the table, so I use this code:
这就是为什么因为主键包含值。我想计算表中的所有行，所以我使用以下代码：
String sql = "SELECT COUNT(d) FROM Defaults d";
Query q = em.createQuery(sql);
long count = (long)q.getSingleResult();
But I am getting this error:
但我收到此错误：
org.hibernate.exception.SQLGrammarException: could not execute query
...
java.sql.SQLSyntaxErrorException: ORA-00907: The right expression is missing from the arithmetic expression
What is the problem? The other count queries with other entities are working.
问题是什么？与其他实体的其他计数查询正在工作。
I am using hibernate.
我正在使用休眠。
回答by Sabuj Hassan
Use count(d.ertek)or count(d.id)instead of count(d). This can be happen when you have composite primary key at your entity.
使用count(d.ertek)或count(d.id)代替count(d)。当您的实体具有复合主键时，就会发生这种情况。
