execute a query using entity manager

Question

I have a query to get the size of databases I have. I have written the following:

@SuppressWarnings("unchecked")
List<Long> results = (List<Long>) em.createQuery("SELECT sum( data_length + index_length ) / 1024 / 1024 \"DataBaseSizeinMB\" FROM information_schema.TABLES GROUP BY table_schema ").getResultList();

where em is the EntityManager. The query on its own runs successfully in phpadmin. But when I run it in my java code, I get exception.

EDIT: The answer is this:

List<Object> list = (List<Object>) em.createNativeQuery(
         "SELECT sum( data_length + index_length ) / 1024 / 1024 FROM information_schema.TABLES GROUP BY table_schema "
).getResultList();


for (Object record : list) {
    double sum = (double) Double.parseDouble(record.toString());
    System.out.println(sum);
}

What exception do you get?

LHA
– LHA

2016-03-16 13:23:10 +00:00
Commented Mar 16, 2016 at 13:23 — LHA
– LHA, Commented Mar 16, 2016 at 13:23
add StackTrace Please .. :)

Vikrant Kashyap
– Vikrant Kashyap

2016-03-16 13:24:51 +00:00
Commented Mar 16, 2016 at 13:24 — Vikrant Kashyap
– Vikrant Kashyap, Commented Mar 16, 2016 at 13:24
the trace is there now.

Pegah
– Pegah

2016-03-16 13:57:49 +00:00
Commented Mar 16, 2016 at 13:57 — Pegah
– Pegah, Commented Mar 16, 2016 at 13:57

kai · Accepted Answer · 2016-03-16 13:32:10Z

3

It works on phpmyadmin because it's a native query. Try using em.createNativeQuery(). That method should be used for plain SQL queries. em.createQuery() accept queries written in JPQL (Java Persistence Query Language).

Docs of createNativeQuery(String sqlString):

@param sqlString a native SQL query string

Docs of createQuery(String qlString):

@param qlString a Java Persistence query string

answered Mar 16, 2016 at 13:32

kai

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Comments

Simon Martinelli · Accepted Answer · 2016-03-16 13:24:57Z

0

It probably the \"DataBaseSizeinMB\"

Try to remove this.

Additionally you should always post the Stack Trace here

answered Mar 16, 2016 at 13:24

Simon Martinelli

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