friends! I have these entities: Document: and ChangeNotice: And these are my repositories: For Document: and for ChangeNotice: So, when i want to get Document with changeNotices, thats not a problem, i have only one select. But when i want to get ChangeNotice with documents – i have (n + 1), first for d…
Tag: hibernate
JPA batch_size property does not work for native query
I’m trying to make a bulk insert with a native query. I’ve added batch_size property to the application.properties file But in the logs, I see that every insert processed separately. Is it possible to apply batching to native query? Answer If the entities use GenerationType.IDENTITY identifier gen…
Case condition in hql
What I’m trying to achieve with this query is: always do the “mother” conditional, but if there isn’t mother, then do the “dad” conditional, is this posible? Answer This query: will try to join first by matching the column idMother to :idMother. If this is not possible then…
SQL / Hibernate insert only if url not exists
I have a list of urls and a table that contains urls. I want to only insert if the url is not in the table. After the insert the Data-table should be contain: My current attempt is to have a method findByURL(url):List and a call this method for every URL in the list. If the returned list is empty I
Are these SQL queries equivalent? And which is better or is there a better option?
I am working on a Spring web application that utilizes hibernate to connect to a DB2 database. I am try to optimize a service method that gets called may times during a wed service call by reducing …
Can somebody help to translate this MySql query to JPQL or HQL?
Don’t forget to check the image below Objects: 1) Question 2) Tags The relationship is ManyToMany The MySql query is following: Need to translate to JPQL or HQL The main goal is to get list of the most frequency tags like:enter image description here Answer Try: The given JPA query is translated to SQL …
ERROR 1054 (42S22): Unknown column ‘pc.project_id’ in ‘on clause’ even when column project_id exists
I am trying to get a sum from my DB with a query written in hibernate @Query(value = “SELECT COALESCE(sum(charge),0) FROM initial_charge I INNER JOIN task T ON T.id = I.task_id ” +” …
[21000][1242] Subquery returns more than 1 row
My Query: Here I get the error – [21000][1242] Subquery returns more than 1 row By the method of exceptions, I determined that the error in this query string: How to make the correct request so that there is no this error? Thank! Answer Two common ways are aggregation and limiting: However, those are re…
How to compare timestamp in HIBERNATE query?
I have one value of timestamp that I retrieve from the database and then compare it with the current timestamp. I actually want to retrieve data of people who have been logged in for the last two hours. Unfortunately, I am facing this error. please help me, guys. I shall be thankful to you. I have stuck in th…
What to use: sql migration or entity setups in Spring/Hibernate?
I am little confused, when see, why most programmers use annotation-based setup for database table constraints. For example @Column(unique=true, nullable=false) Why do we need that, if(as I heard) …