All
I am trying to use dblink in PostgreSQL to run query on different databases. The following works if the table "user" is under the public schema:
select * from dblink(
'hostaddr=1.2.3.4 port=5434 dbname=dbname user=username password=password',
'select id from user')
as t1(
id bigint
);
However, I need to run the query on some other defined schemas. Does anyone know how to add the schema information in the above query? I can't figure it out from the PostgreSQL docs.
When you write SQL query like
SELECT id FROM user
PostgreSQL will resolve table name like user into fully qualified name like schema.tablename using schema search path, which by default is set to "$user",public.
In other words, user will resolve into public.user unless you tweaked server configuration.
However, you can specify schema explicitly in your statement, like this:
SELECT id FROM otherschema.user
Related
I am new with DB2.
I am not able to get data from a table without using the schema name. If I use a schema name with table name, I am able to fetch data.
Example:
SELECT * FROM TABLE_NAME;
It is giving me error, while
SELECT FROM SCHEMA_NAME.TABLE_NAME;
is fetching a result.
What do I have to set up not to always have to use the schema name?
By default, your username is used as the schema name for unqualified object names. You can see the current schema with, e.g. VALUES CURRENT SCHEMA. You can change the current schema for you current session with SET SCHEMA new_schema_name, or via e.g. a JDBC connection parameter. Most query tools also have a place to specify/change the current schema.
See the manual page for SET SCHEMA https://www.ibm.com/support/knowledgecenter/en/SSEPGG_11.1.0/com.ibm.db2.luw.sql.ref.doc/doc/r0001016.html
The full rules for the qualification of unqualified objects is here https://www.ibm.com/support/knowledgecenter/en/SSEPGG_11.1.0/com.ibm.db2.luw.sql.ref.doc/doc/r0000720.html#r0000720__unq-alias
E.g.
Unqualified alias, index, package, sequence, table, trigger, and view names are implicitly qualified by the default schema.
However, you can create a public alias for a table, module or sequence if you wish to be able to reference it regardless of your CURRENT SCHEMA value.
https://www.ibm.com/support/knowledgecenter/SSEPGG_11.5.0/com.ibm.db2.luw.sql.ref.doc/doc/r0000910.html
(P.S. all the above assumes you are using Db2 LUW)
Try using SET SCHEMA to set the default schema to be used in the session:
SET SCHEMA SCHEMA_NAME;
SELECT * FROM TABLE_NAME;
When using DBeaver - right click on connection > Connection Settings > Initialization, and select your default DB and default Schema:
After that, open your SQL Script and select Active DB:
Whenever i have to execute sql commands in pgAdmin 4 i have to append schema_name with tables.
Eg :-
SELECT * FROM my_schema.users //where myschema is schema name
ORDER BY id ASC
Is there any way to execute sql commands in pgAdmin 4 without schema name, by setting a default schema in advance.
Some thing like this
SELECT * FROM programme
ORDER BY id ASC
- without specifying schema name with table.
Is there a way to set default schema in pgAdmin 4 for querying in sql tool?
You can do it in 2 ways:
SET search_path = my_schema, "$user", public; -- For current session only
ALTER ROLE your_role SET search_path = my_schema, "$user", public; -- Persistent, for role
You can also set it for whole database, same way as for role.
EDIT: Just to explain what this does - it will change where and in what order Postgres will search for objects matching object identifiers that did not get prefixed with schema name.
You might need also to restart pgAdmin4 in order for the search_path to start working. At least it was my case.
A good double check if the search_path was set in pgAdmin4 is to go to:
Login/Group Roles -> Right click on the user (by default it is 'postgres') -> Properties -> Parameters tab. Here you should see your new parameter 'search_path' with the value 'your_schema_name'.
Simple question, however google can't help in reasonable time.
Ok, I have user table in my_db database with id column.
I want to run very simple query
SELECT id FROM user;
but it fails.
ERROR: column "id" does not exist LINE 1: SELECT id FROM user;
Can you imagine?
Ok, Running
SELECT * FROM user;
outputs the list of internal postgresql database users, which is nothing to do with my users, it's data from completely another [internal] database.
However, connection with my_db was established.
user is an internal function (and a reserved word) returning the currently logged in user.
To use that as your own identifier, you need to quote it:
select id
from "user"
or
select id
from public."user".
But you should really avoid reserved words as table names (or any name that requires quoting the identifier)
The following query can be rewritten as
SELECT id FROM my_db.public.user;
Where id is column, my_db is database, user is table name, public - is the schema. More about schemas:
http://www.postgresql.org/docs/9.1/static/ddl-schemas.html
So you don't have to rename the table name.
I'm currently using a schema that will be changed to another schema in a couple of months. I do not not want to have to remove the SCHEMA_NAME multiple times from each report. All the reports so far have this format:
SELECT
COLUMN_NAME1,
SCHEMA_NAME.USER_DEFINED_FUNCTION(COLUMN_NAME2),
COLUMN_NAME3
FROM
SCHEMA_NAME.TABLE_NAME
I want to remove the schema name from the query so it looks like this:
SET SCHEMA LROUIM;
SET PATH LROUIM;
SELECT
COLUMN_NAME1,
USER_DEFINED_FUNCTION(COLUMN_NAME2),
COLUMN_NAME3
FROM
TABLE_NAME
I need the "SET SCHEMA" for the table name and "SET PATH" for the User Defined Function. This code works in Squirrel SQL, but if I insert this code into a Birt data set of type SQL SELECT QUERY, I get an error because of
SET SCHEMA LROUIM;
SET PATH LROUIM;
How do I implement SET SCHEMA and SET PATH in a SQL Select Query in Birt?
I think BIRT uses a JDBC connexion, and you can modify the connection parameters by specifying a default schema.
I have a schema called application. Is there a way that, rather than using the syntax
SELECT * FROM application.table
I can set the default schema so that I can just use
SELECT * FROM table
It would be the same idea as a using statement I suppose.
The default schema for all sql server users is "dbo", You can alter the default schema for a user by using commands ALTER USER
ALTER USER UserName WITH DEFAULT_SCHEMA = application;
It will be great to have a use statement for schemas.
You can vote the feature suggestion on Microsoft connect.