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Set random seed on Postgres using hibernate

I'm not very familiar with Hibernate, but I need to set the random seed on a PostgreSQL database using Hibernate.
This is what I'm trying to run:
String seedSql = "select setseed(0.123)";
Query seedQuery = entityManager.createQuery(seedSql);
seedQuery.getSingleResult();
However, this query does not return any entity mapped by Hibernate, thus I'm receiving the following error:
org.hibernate.QueryException: No data type for node: org.hibernate.hql.internal.ast.tree.MethodNode (...)
Any suggestions?

According to the docs, createQuery() takes a JPQL string, and apparently doesn't know what to do with your Postgres function call.
To run an SQL query, use createNativeQuery() instead.

After some trial and error I noticed that I had to use .createNativeQuery() since setseed() is a function from PostgreSQL:
String seedsql = "select cast(setseed(0.123) as text)";
Query seedQuery = DatabaseInterface.getEm().createNativeQuery(seedsql);
seedQuery.setMaxResults(1).getSingleResult();
I used cast(setseed(0.123) as text) to avoid another error:
org.hibernate.MappingException: No Dialect mapping for JDBC type: 1111

JPA: Equivalent for Oracle's REGEXP_SUBSTR

I have following Oracle SQL query:
SELECT SUBSTR(col, 0, INSTR(col, REGEXP_SUBSTR(col, '\.\d+$')) -1) AS col_new, col as col_orig AS col_orig FROM tab;
I have data in table like:
col
ABC.A.01
ABC.A.02
Above query returns results like:
col_new col_orig
ABC.A ABC.A.01
ABC.A ABC.A.02
I am trying to migrate it to JPA named query. Till now I could make query only like this:
SELECT SUBSTRING(f.col, 0, LENGTH(f.col) - LOCATE('.', REVERSE(f.col))), f.col FROM tab f;
I did this as I was not able to find equivalent in JPA for Oracle's REGEXP_SUBSTR. My JPA named query fails in data examples like ABC.A.P01.
Can you please let me know how can I migrate my SQL query to JPA named query using equivalent for REGEXP_SUBSTR.

I found that there is no equivalent for REGEXP_SUBSTR in JPA. So I decided to stick to native query execution.

If you are using eclipselink, use SQL to integrate SQL within a JPQL statement. This provides an alternative to using native SQL queries simply because the query may require a function not supported in JPQL.
The SQL function includes both the SQL string (to inline into the JPQL statement) and the arguments to translate into the SQL string. Use a question mark character ( ? ) to define parameters within the SQL that are translated from the SQL function arguments.
You can use SQL to call database functions with non standard syntax, embed SQL literals, and perform any other SQL operations within JPQL. With SQL, you can still use JPQL for the query.
Example
select o from Entity o order by SQL('REGEXP_SUBSTR(?, ''[0-9]+'', 1, 1)', o.code)

Get dynamic SQL column names from Hibernate

I have an Oracle table that has a CLOB in it. Inside this CLOB can be a SQL statement. This can be changed at any time.
I am currently trying to dynamically run these SQL statements and return the column names and data back. This is to be used to dynamically create a table on the web page.
Using Hibernate, I create the query and get the data like so:
List<Object[]> queryResults = null;
SQLQuery q = session.createSQLQuery(sqlText);
queryResults = q.list();
This gets the data I need, but not the column names. I have tried using the getReturnAliases() method, but it throws an error that the "java.lang.UnsupportedOperationException: SQL queries do not currently support returning aliases"
So my question is: Is there a way through Hibernate to get these values dynamically?

You can use :
q.setResultTransformer(AliasToEntityMapResultTransformer.INSTANCE);
List<Map<String,Object>> aliasToValueMapList=query.list();
to get column names in createSQLQuery.
For more details please refer to this question.

You can use the addScalar method to define the columns.
Look at 16.1.1
https://docs.jboss.org/hibernate/orm/3.3/reference/en-US/html/querysql.html

You could implement a ResultTransformer ( http://docs.jboss.org/hibernate/orm/4.3/javadocs/org/hibernate/transform/ResultTransformer.html ) and set it on the native query. I think with a native SQL query you get the aliases as specified in the SQL as alias parameter in the callback method.

In 2018 I would suggest using NativeQueryTupleTransformer with native queries.
query.setResultTransformer(new NativeQueryTupleTransformer());
The result format is List<Tuple>. This format is very convenient to work with native SQL queries.

hibernate HQL query that supports multiple databases oracle and mysql

I have an application that should support oracle and mysql databases.
I will get different configuration for different database.
But i want all HSQL used in the code to be intact.
But i am not able to do so bcoz of below :
I have created a query like below:
String SQL_QUERY = "select count(log) from dbtable where created_date='"+ givenDate
Query query = session.createQuery(SQL_QUERY);
query.uniqueResult();
This works very well in mysql
but not in oracle
because oracle db expects formatting the value of created_date column with
to_date(givenDate,"yyyy-MM-dd")
so i have to change the above query as :
String SQL_QUERY = "select count(log) from dbtable where created_date=to_date('"+ givenDate+","yyyy-MM-dd")
Can I avoid this multiple query declarations in any way for mysql and oracle ??

Create a java.sql.Date out of that String and pass it to the query; don't embed the conversion in the database.
Better yet, bind the String to a Date long before it gets to the persistence tier. Java's an object-oriented language; think in terms of objects.

Hibernate session.createQuery error while replace method with single quote

I got very typical issue. My dynamically generated query like this...
UPDATE Templates t SET t.TEMPLATE_DATA = replace(t.TEMPLATE_DATA, 'Test\'s Test', 'Kent"s Test'), t.TEMPLATE_DATA = replace(t.TEMPLATE_DATA, 'Test"s Test', 'Kent"s Test'), UPDATE_DATE = NOW() where PRACTICE_ID = 1 AND CATEGORY_ID IN (1)
This works perfect when I explictily fire this query in db. but by using hibernate's session.createQuery(-- my query --) if thwows an error QueryTranslatorException.
Database : Mysql 5.3
Have any one faced this issue?
Thanks in advance.

Try to run this in Hibernate as native SQL query:
session.createSQLQuery(-- query text --);
Because if you use
session.createQuery(-- query text --);
Hibernate will try to execute it as HQL query which differs from usual SQL query.
HQL is object oriented query language. It operates in terms of objects rather then in terms of tables. Here posted a brief description of difference between SQL and HQL. But if you have time better to read appropriate sections of hibernate's documentation about HQL and Native SQL usage.

If you want to execute SQL Query in hibernate, Use : session.createSQLQuery(String query);