I am trying to do insert using hibernate and am running into an issue. When I use the following code
#Override
public Serializable addTestResult(Result test_result) {
// TODO Auto-generated method stub
return getCurrentSession().save(test_result);
}
the end query looks like this:
mysql> insert into test_results (db, host) values ('db1', 'host1');
which gets rejected by mysql since there are left tick missing in the column name. How can I have hibernate add quotes around the column name so that the query looks like this:
mysql> insert into test_results (`db`, `host`) values ('db1', 'host1');
Quote the table/ column names you need quoted with ` back-ticks in your .hbm.xml or mapping annotations.
For example:
<property name='DB" column='`db`' />
#Column(name="`db`")
This tells Hibernate to quote these identifiers to the database. I use this, for example, with a `USER` table. As with any app, most table & column-names are not conflicting but user tends to be a SQL keyword.
You don't need to switch on quoting globally.
Try to add the option hibernate.globally_quoted_identifiers=true.
Source: Automatic reserved word escaping for Hibernate tables and columns
Related
I am using JPA to generate a script for creating database tables based on my entities:
javax.persistence.schema-generation.scripts.action=create
javax.persistence.schema-generation.scripts.create-target=db_setup.sql
The file is generated with the correct tables, however the statements do not end with a semicolon, for example:
create table hibernate_sequence (next_val bigint)
insert into hibernate_sequence values ( 1 )
insert into hibernate_sequence values ( 1 )
I assume this is valid in standard SQL? However, it is not valid in MySQL. Is there a way to tell JPA to add the semicolons to the end of the line? Or what else could be the reason that it is missing?
Since Hibernate 5.1.0, the line delimiter for the generated SQL can be defined by setting the hibernate.hbm2ddl.delimiter property, e.g.
hibernate.hbm2ddl.delimiter=";"
The default is no delimiter.
See also comments on this ticket.
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)
If I have a SQL table with columns:
NR_A, NR_B, NR_C, NR_D, R_A, R_B, R_C
and on runtime, I add columns following the column's sequence such that the next column above would be R_D followed by R_E.
My problem is I need to reset the values of columns that starts with R_ (labeled that way to indicate that it is resettable) back to 0 each time I re-run my script . NR_ columns btw are fixed, so it is simpler to just say something like:
UPDATE table set col = 0 where column name starts with 'NR_'
I know that is not a valid SQL but I think its the best way to state my problem.
Any thoughts?
EDIT: btw, I use postgres (if that would help) and java.
SQL doesn't support dynamically named columns or tables--your options are:
statically define column references
use dynamic SQL to generate & execute the query/queries
Java PreparedStatements do not insulate you from this--they have the same issue, just in Java.
Are you sure you have to add columns during normal operations? Dynamic datamodels are most of the time a realy bad idea. You will see locking and performance problems.
If you need a dynamic datamodel, take a look at key-value storage. PostgreSQL also has the extension hstore, check the contrib.
If you don't have many columns and you don't expect the schema to change, just list them explicitly.
UPDATE table SET NR_A=0;
UPDATE table SET NR_B=0;
UPDATE table SET NR_C=0;
UPDATE table SET NR_D=0;
Otherwise, a simple php script could dynamically build and execute your query:
<?php
$db = pg_connect("host=localhost port=5432 user=postgres password=mypass dbname=mydb");
if(!$db) die("Failed to connect");
$reset_cols = ["A","B","C","D"];
foreach ($col in $reset_cols) {
$sql = "UPDATE my_table SET NR_" . $col . "=0";
pg_query($db,$sql);
}
?>
You could also lookup table's columns in Postgresql by querying the information schema columns tables, but you'll likely need to write a plpgsql function to loop over the query results (one row per table column starting with "NR_").
if you rather using sql query script, you should try to get the all column based on given tablename.
maybe you could try this query to get all column based on given tablename to use in your query.
SELECT attname FROM
pg_attribute, pg_type
WHERE typname = 'tablename' --your table name
AND attrelid = typrelid
AND attname NOT IN ('cmin', 'cmax', 'ctid', 'oid', 'tableoid', 'xmin', 'xmax')
--note that this attname is sys column
the query would return all column with given tablename except system column