I&#39;m not sure for JPA 1.0 but you can pass a `Collection` in JPA 2.0:

    String qlString = &quot;select item from Item item where item.name IN :names&quot;; 
    Query q = em.createQuery(qlString, Item.class);

    List&lt;String&gt; names = Arrays.asList(&quot;foo&quot;, &quot;bar&quot;);

    q.setParameter(&quot;names&quot;, names);
    List&lt;Item&gt; actual = q.getResultList();

    assertNotNull(actual);
    assertEquals(2, actual.size());

Tested with EclipseLInk. With Hibernate 3.5.1, you&#39;ll need to surround the parameter with parenthesis:

    String qlString = &quot;select item from Item item where item.name IN (:names)&quot;;

But this is a bug, the JPQL query in the previous sample is valid JPQL. See [HHH-5126][1].


  [1]: https://hibernate.atlassian.net/browse/HHH-5126

The oracle limit is 1000 parameters. The issue has been resolved by hibernate in version 4.1.7 although by splitting the passed parameter list in sets of 500
 [see JIRA HHH-1123][1]


  [1]: https://hibernate.atlassian.net/browse/HHH-1123

I had a problem with this kind of sql, I was giving empty list in IN clause(always check the list if it is not empty). Maybe my practice will help somebody.

I have written an R script that pulls some data from a database, performs several operations on it and post the output to a new database. 

I would like this script to run every day at a specific time but I can not find any way to do this effectively. 

Can anyone recommend a resource I could look at to solve this issue? I am running this script on a Windows machine.

Scheduling R Script

After finishing my C++ class it seemed to me the structs/classes are virtually identical except with a few minor differences.

I&#39;ve never programmed in C before; but I do know that it has structs. In C is it possible to inherit other structs and set a modifier of public/private?

If you can do this in regular C why in the world do we need C++? What makes classes different from a struct?

C/C++ Struct vs Class

I would like to load all objects that have a textual tag set to any of a small but arbitrary number of values from our database. The logical way to go about this in SQL would be to build an &quot;IN&quot; clause. JPQL allows for IN, but it seems to require me to specify every single parameter to IN directly (as in, &quot;in (:in1, :in2, :in3)&quot;).

Is there some way to specify an array, or a list (or some other container) that should be unrolled to the values of an IN clause?

JPQL IN clause: Java-Arrays (or Lists, Sets...)?

<p>I would like to load all objects that have a textual tag set to any of a small but arbitrary number of values from our database. The logical way to go about this in SQL would be to build an "IN" clause. JPQL allows for IN, but it seems to require me to specify every single parameter to IN directly (as in, "in (:in1, :in2, :in3)").</p>
<p>Is there some way to specify an array, or a list (or some other container) that should be unrolled to the values of an IN clause?</p>


I have a large number of rows that I would like to copy, but I need to change one field.

I can select the rows that I want to copy:

    select * from Table where Event_ID = &quot;120&quot;

Now I want to copy all those rows and create new rows while setting the `Event_ID` to `155`. How can I accomplish this?

MySQL: How to copy rows, but change a few fields?

I am trying to dump the contents of a table to a csv file using a MySQL SELECT INTO OUTFILE statement.  If I do:

    SELECT column1, column2
    INTO OUTFILE &#39;outfile.csv&#39;
    FIELDS TERMINATED BY &#39;,&#39;
    FROM table_name;

outfile.csv will be created on the server in the same directory this database&#39;s files are stored in.  

However, when I change my query to:

    SELECT column1, column2
    INTO OUTFILE &#39;/data/outfile.csv&#39;
    FIELDS TERMINATED BY &#39;,&#39;
    FROM table_name;

I get:

    ERROR 1 (HY000): Can&#39;t create/write to file &#39;/data/outfile.csv&#39; (Errcode: 13)

Errcode 13 is a permissions error, but I get it even if I change ownership of /data to mysql:mysql and give it 777 permissions.  MySQL is running as user &quot;mysql&quot;.

Strangely I can create the file in /tmp, just not in any other directory I&#39;ve tried, even with permissions set such that user mysql should be able to write to the directory.

This is MySQL 5.0.75 running on Ubuntu.  

How can I get around MySQL Errcode 13 with SELECT INTO OUTFILE?

I&#39;ve got a monitoring system that is collecting data every n seconds (n is approximately 10 but varies).  I&#39;d like to aggregate the collected data by 15 minute intervals.  Is there a way to consolidate the timestamp values into 15 minute chunks to allow for grouping to work?

Group mysql query by 15 min intervals

I&#39;m creating an SQL setup script and I&#39;m using someone else&#39;s script as an example.  Here&#39;s an example of the script:

    SET ANSI_NULLS ON
    GO
    SET QUOTED_IDENTIFIER ON
    GO
    CREATE TABLE [dbo].[be_Categories](
    	[CategoryID] [uniqueidentifier] ROWGUIDCOL  NOT NULL CONSTRAINT [DF_be_Categories_CategoryID]  DEFAULT (newid()),
    	[CategoryName] [nvarchar](50) NULL,
    	[Description] [nvarchar](200) NULL,
    	[ParentID] [uniqueidentifier] NULL,
     CONSTRAINT [PK_be_Categories] PRIMARY KEY CLUSTERED 
    (
    	[CategoryID] ASC
    )WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
    ) ON [PRIMARY]
    GO

Does anyone know what the ON [PRIMARY] command does?

What does ON [PRIMARY] mean?

In my table I have a field named `eventdate` in `datetime` format like `2010-05-11 00:00:00`.

How do i make a query so that it adds **one day** to the `eventdate` eg if today is `2010-05-11`, i want to show in `where` clause to return all records with tomorrow&#39;s date.

**Update:**

I tried this:

`select * from fab_scheduler where custid = 1334666058 and DATE_ADD(eventdate, INTERVAL 1 DAY)
`

But unfortunately it returns the same record even if i add an interval greater than 1.

**Result:**

`2010-05-12 00:00:00`

But i only want to select records with tomorrow&#39;s date.

MySQL: How to add one day to datetime field in query

What&#39;s the difference between `@Basic(optional = false)` and `@Column(nullable = false)` in JPA persistence?

@Basic(optional = false) vs @Column(nullable = false) in JPA

&gt; The no-argument constructor is a
&gt; requirement (tools like Hibernate use
&gt; reflection on this constructor to
&gt; instantiate objects).

I got this hand-wavy answer but could somebody explain further? Thanks

Why does Hibernate require no argument constructor?

My Java bean has a childCount property. This property is **not mapped to a database column**. Instead, it should be **calculated by the database with a `COUNT()` function** operating on the join of my Java bean and its children. It would be even better if this property could be calculated on demand / &quot;lazily&quot;, but this is not mandatory.

In the worst case scenario, I can set this bean&#39;s property with HQL or the Criteria API, but I would prefer not to.

The Hibernate `@Formula` annotation may help, but I could barely find any documentation.

Any help greatly appreciated. Thanks.

How to map calculated properties with JPA and Hibernate

To empty a database table, I use this SQL Query:

    TRUNCATE TABLE `books`

How to I truncate a table using Django&#39;s models and ORM?

I&#39;ve tried this, but it doesn&#39;t work:

    Book.objects.truncate()

How to TRUNCATE TABLE using Django&#39;s ORM?

I am a newbie to Java Persistence API and Hibernate. 

What is the difference between [`FetchType.LAZY`](http://docs.oracle.com/javaee/7/api/javax/persistence/FetchType.html) and [`FetchType.EAGER`](http://docs.oracle.com/javaee/7/api/javax/persistence/FetchType.html) in Java Persistence API? 

Difference between FetchType LAZY and EAGER in Java Persistence API?

I am trying to introduce a multi-key constraint on a JPA-mapped entity:

    public class InventoryItem {
        @Id
        private Long id;
 
        @Version 
        private Long version;

        @ManyToOne
        @JoinColumn(&quot;productId&quot;)
        private Product product;

        @Column(nullable=false);
        private long serial;
    }

Basically (product, serial) pair should be unique, but I only found a way to say that serial should be unique.  This obviously isn&#39;t a good idea since different products might have same serial numbers.  

Is there a way to generate this constraint via JPA or am I forced to manually create it to DB?

How to introduce multi-column constraint with JPA annotations?

I&#39;m using JPA 2.0/Hibernate validation to validate my models. I now have a situation where the combination of two fields has to be validated:


    public class MyModel {
        public Integer getValue1() {
            //...
        }
        public String getValue2() {
            //...
        }
    }

The model is *invalid* if both `getValue1()` and `getValue2()` are `null` and valid otherwise.

How can I perform this kind of validation with JPA 2.0/Hibernate? With a simple `@NotNull` annotation both getters must be non-null to pass validation.






How can I validate two or more fields in combination?

I want to use JPA (eclipselink) to get data from my database. The database is changed by a number of other sources and I therefore want to go back to the database for every find I execute. I have read a number of posts on disabling the cache but this does not seem to be working. Any ideas?

I am trying to execute the following code:
 

            EntityManagerFactory entityManagerFactory =  Persistence.createEntityManagerFactory(&quot;default&quot;);
            EntityManager em = entityManagerFactory.createEntityManager();
            
            MyLocation one = em.createNamedQuery(&quot;MyLocation.findMyLoc&quot;).getResultList().get(0);
    
            MyLocation two = em.createNamedQuery(&quot;MyLocation.findMyLoc&quot;).getResultList().get(0);    
    
            System.out.println(one==two);

one==two is true while I want it to be false.

I have tried adding each/all the following to my persistence.xml

    &lt;property name=&quot;eclipselink.cache.shared.default&quot; value=&quot;false&quot;/&gt;
    &lt;property name=&quot;eclipselink.cache.size.default&quot; value=&quot;0&quot;/&gt;
    &lt;property name=&quot;eclipselink.cache.type.default&quot; value=&quot;None&quot;/&gt;

I have also tried adding the @Cache annotation to the Entity itself:

    @Cache(
      type=CacheType.NONE, // Cache nothing
      expiry=0,
      alwaysRefresh=true
    )

Am I misunderstanding something?


Disable caching in JPA (eclipselink)

What exactly does setting the length on a column do in JPA?

	@Column(name = &quot;middle_name&quot;, nullable = false, length = 32)
	public String getMiddleName() {
		return this.middleName;
	}

I understand that you can use the annotations to generate the database schema (DDL) based on the entity objects, but does length do any sort of check or truncation when persistence happens, or it solely used for schema creation?

I also realize that JPA can sit on top of various implementations, the implementation I am concerned with in this case is Hibernate.

What does the length attribute do when set on the @Column JPA annontation?

How it is possible to limit the number of results retrieved from a database?


&lt;pre&gt;&lt;code&gt;select e from Entity e /* I need only 10 results for instance */&lt;/code&gt;&lt;/pre&gt;

Limit number of results in JPQL

My Java application is using JPA for object persistence. The business domain is very simple (just three classes are persistent, with 3-5 properties in each). Queries are simple as well. The question is which approach I should use: JPQL or Criteria API?

What to use: JPQL or Criteria API?

I have built a NamedQuery that looks like this:

    @NamedQuery(name = &quot;EventLog.viewDatesInclude&quot;,
            query = &quot;SELECT el FROM EventLog el WHERE el.timeMark &gt;= :dateFrom AND &quot;
            + &quot;el.timeMark &lt;= :dateTo AND &quot;
            + &quot;el.name IN (:inclList)&quot;)

What I want to do is fill in the parameter :inclList with a list of items instead of one item.  For example if I have a `new List&lt;String&gt;() { &quot;a&quot;, &quot;b&quot;, &quot;c&quot; }` how do I get that in the :inclList parameter?  It only lets me codify one string.   For example:

    setParameter(&quot;inclList&quot;, &quot;a&quot;) // works
    
    setParameter(&quot;inclList&quot;, &quot;a, b&quot;) // does not work
    
    setParameter(&quot;inclList&quot;, &quot;&#39;a&#39;, &#39;b&#39;&quot;) // does not work
    
    setParameter(&quot;inclList&quot;, list) // throws an exception

I know I could just build a string and build the whole Query from that, but I wanted to avoid the overhead.   Is there a better way of doing this?

Related question: if the List is very large, is there any good way of building query like that? 

Adding IN clause List to a JPA Query

I&#39;m using Toplink essentials (JPA) + GlassFish v3 + NetBean 6.9

I have one table with composite primary key:

    table (machine)
    ----------------
    |PK machineId  |
    |PK workId     |
    |              |
    |______________|

I created 2 entity classes one for entity itself and second is PK class.

    public class Machine {
       @EmbeddedId
       protected MachinePK machinePK;
    
       //getter setters of fields..
    }
    
    public class MachinePK {
        @Column(name = &quot;machineId&quot;)
        private String machineId;
    
        @Column(name = &quot;workId&quot;)
        private String workId;
    
    }

Now.. **how do I write SELECT clause with JPQL with WHERE???**

This fails.

    SELECT m FROM Machine m WHERE m.machineId = 10

http://www.mail-archive.com/users@openjpa.apache.org/msg03073.html

According to the web page, add &quot;val&quot;? No it fails too.

       SELECT m FROM Machine m WHERE m.machineId.val = 10

In both case, the error is:

        Exception Description: Error compiling the query 
    [SELECT m FROM Machine m WHERE m.machineId.val = 10], 
    line 1, column 30: unknown state or association field 
    [MachineId] of class [entity.Machine].

How to write JPQL SELECT with embedded id?

I have the following parametrised JPA, or Hibernate, query:

    SELECT entity FROM Entity entity WHERE name IN (?)

I want to pass the parameter as an ArrayList&amp;lt;String&gt;, is this possible? Hibernate current tells me, that

    java.lang.ClassCastException: java.util.ArrayList cannot be cast to java.lang.String

Is this possible at all?

**ANSWER**: Collections as parameters only work with named parameters like &quot;`:name`&quot;, not with JDBC style parameters like &quot;`?`&quot;.

Content Type	Original Author	Original Content on Stackoverflow
Question	Bernd Haug	View Question on Stackoverflow
Solution 1 - Sql	Pascal Thivent	View Answer on Stackoverflow
Solution 2 - Sql	Ashish Thukral	View Answer on Stackoverflow
Solution 3 - Sql	Vahan Yeghyan	View Answer on Stackoverflow

JPQL IN clause: Java-Arrays (or Lists, Sets...)?

Sql Problem Overview

Sql Solutions

Solution 1 - Sql

Solution 2 - Sql

Solution 3 - Sql

C/C++ Struct vs Class

Scheduling R Script

Attributions