I'm using Hibernate and a MySql server. I use multiple databases as "namespaces" (e.g. users, transactions, logging etc.).
So, I configued Hibernate to NOT connect to a particular database :
url = jdbc:mysql://127.0.0.1/
The databases where tables are located are defined in the hbm files through the catalog attribute :
<class name="com.myApp.entities.User" table="user" schema="" catalog="users"> ...
When I want to load some data, everything works fine and Hibernate seems to generate the expected SQL queries (by using the catalog prefix in the table names) e.g. :
select id from users.user
However, when I try to add a new record, Hibernate don't use the from [catalog].[table_name] syntax anymore. So I get a MySQL error 'No database selected'.
select max(id) from user
Hibernate is trying the get the future id to create a new record, but it doesn't specify in which database is located the table, it should be :
select max(id) from users.user
Why is Hibernate generating this invalid query ? Have someone ever experienced this problem ?
You need to specify the schema for the generator. See this question on SO for a more detailed answer.
Related
I'm updating old libraries from a legacy system. Just now i'm trying to update Hibernate 3.4.0.GA to 4.3.11.Final, i just needed to change small things in the code, everything was fine. But when i put the system to run, i'm receiving a "schema "FOO" does not exist" while execute a query. Trying to isolate the problem, i discovered this happen from Hibernate 3.5.1 to 3.5.2 and the reasons.
Hibernate when generating the sql, is adding schema to functions. I show now the difference in two versions.
protocolo_1 is the alias of main schema, this is a subquery added by #Formula in Protocolo.java, the name of schema is protocolo too.
#Formula
select max (pm2.id) from protocolo.protocolomovimento pm2 where pm2.id_protocolo = id
Hibernate 3.5.1 SQL generated
select max (pm2.id) from protocolo.protocolomovimento pm2 where pm2.id_protocolo = protocolo1_.id
Hibernate 3.5.2 SQL generated
select protocolo_1.max (pm2.id) from protocolo.protocolomovimento pm2 where pm2.id_protocolo = protocolo1_.id
I'm using PostgreSQL 9.4.12 with respective driver and org.hibernate.dialect.PostgreSQLDialect (in this versions of hibernate, it's the unique dialect to PostgreSQL)
I found another guy with similar problem here Why is Hibernate adding schema name to Hsql functions? but i think its only similar, it's not my case.
Why is Hibernate doing this? How can i fix this?
Looks like hibernate don't understand space character between max and ( in expression max (pm2.id), so it thinks that max is column name and adds table alias there.
Removing space will solve the problem.
I have Workspace/Schema EDUCATION in Oracle XE.
In my Java code I want execute queries like this: SELECT * FROM Table instead of SELECT * FROM EDUCATION.Table.
When I write query without EDUCATION I have error: table or view does not exist.
I tried to set the default schema to % (screenshot), but it did not help.
How to avoid writing Workspace/Schema name?
If I understand correctly, you want to access tables in other schemas without using the schema name.
One simple way to do this uses synonyms. In the schema you are connect to:
create synonym table for education.table;
Then you can use table where you would use education.table.
I am using an APACHE DERBY database, and basing my database interactions on EntityManager, and I don't want to use JDBC class to build a query to change my tables' names (i just need to put a prefix to each new user to the application, but have the same structure of tables), such as:
//em stands for EntityManager object
Query tableNamesQuery= em.createNamedQuery("RENAME TABLE SCHEMA.EMP_ACT TO EMPLOYEE_ACT");
em.executeUpdate();
// ... rest of the function's work
// The command works from the database command prompt but i don't know how to use it in a program
//Or as i know you can't change system tables data, but here's the code
Query tableNamesQuery= em.createNamedQuery("UPDATE SYS.SYSTABLES SET TABLENAME='NEW_TABLE_NAME' WHERE TABLETYPE='T'");
em.executeUpdate();
// ... rest of the function's work
My questions are :
This syntax is correct?
Will it work?
Is there any other alternative?
Should I just use the SYS.SYSTABLES and find all the tables that has 'T' as tabletype and alter their name their, will it change the access name ?
I think you're looking for the RENAME TABLE statement: http://db.apache.org/derby/docs/10.10/ref/rrefsqljrenametablestatement.html
Don't just issue update statements against the system catalogs, you will corrupt your database.
I need to be able to refer to a table on a different schema, using OpenJPA to access a Sybase db.
So, for example, I need to select as follows:
SELECT name FROM SHARE.dbo.PROVINCE;
However, the generated SQL is:
SELECT name FROM "SHARE.dbo".PROVINCE;
which Sybase rejects. Without the quotes it works fine.
I'm using the following annotations on the class:
#Entity
#Table(name="PROVINCE", schema="SHARE.dbo")
using schema="SHARE" doesn't work, although it generates the sql without any quotes. (Sybase requires schema.owner.table, so SCHEMA.PROVINCES is an unknown object)
Any thoughts on how to resolve this issue?
Try concatenating the schema to the table name: #Table(name="SHARE.dbo.PROVINCE")
This is a bit of a shot in the dark, but you could try to disable delimited identifier support?
openjpa.DBDictionary=sybase(SupportsDelimitedIdentifiers=false)
This is a follow-on question to my earlier question about specifying multiple schemata in java using jooq to interact with H2.
My test H2 DB currently has 2 schemata, PUBLIC and INFORMATION_SCHEMA. PUBLIC is specified as the default schema by H2. When running a query that should extract information from eg INFORMATION_SCHEMA.TABLES the query fails with a "table unknown" SQL error. I am only able to execute such queries by executing a factory.use(INFORMATION_SCHEMA). There are no build errors etc and eclipse properly autocompletes eg TABLES.TABLE_NAME.
If I dont do this, jooq doesnt seem to prepend the appropriate schema even though I create the correct Factory object for the schema eg
InformationSchemaFactory info = new InformationSchemaFactory(conn);
I read about mapping but am a bit confused as to which schema I would use as the input/output.
By default, the InformationSchemaFactory assumes that the supplied connection is actually connected to the INFORMATION_SCHEMA. That's why schema names are not rendered in SQL. Example:
// This query...
new InformationSchemaFactory(conn).selectFrom(INFORMATION_SCHEMA.TABLES).fetch();
// ... renders this SQL (with the asterisk expanded):
SELECT * FROM "TABLES";
The above behaviour should be documented in your generated InformationSchemaFactory Javadoc. In order to prepend "TABLES" with "INFORMATION_SCHEMA", you have several options.
Use a regular factory instead, which is not tied to any schema:
// This query...
new Factory(H2, conn).selectFrom(INFORMATION_SCHEMA.TABLES).fetch();
// ... renders this SQL:
SELECT * FROM "INFORMATION_SCHEMA"."TABLES";
Use another schema's factory, such as the generated PublicFactory:
// This query...
new PublicFactory(conn).selectFrom(INFORMATION_SCHEMA.TABLES).fetch();
// ... renders this SQL:
SELECT * FROM "INFORMATION_SCHEMA"."TABLES";
Use Settings and an appropriate schema mapping to force the schema name to be rendered.
The first option is probably the easiest one.
This blog post here will give you some insight about how to log executed queries to your preferred logger output: http://blog.jooq.org/2011/10/20/debug-logging-sql-with-jooq/