I need to get complete list of external tables in db2 database. I have defined schema called DB2INST1. How to get complete list of external tables information using system tables?
The information lives in syscat.tables (documentation here) for Db2-LUW databases that support external tables, which have their PROPERTY column with value Y in position 27 of that column.
Example query returns the fully qualified name of external tables:
select trim(tabschema)||'.'||rtrim(tabname)
from syscat.tables
where substr(property,27,1)='Y'
with ur;
In general, the best and most reliable way to retrieve all information and to recreate the DDL statements for tables is to use the db2look tool. If you want to extract the metadata on your own, there are some catalog views to start with:
SYSCAT.TABLES holds the table information. Look for the PROPERTY column and check there if it is an external table.
SYSCAT.COLUMNS has the basic column information. But there are more related tables depending on types and attributes.
SYSCAT.EXTERNALTABLEOPTIONS shows the actual options for an external table, the things in addition to what makes a regular table.
There are many more tables to hold table properties, depending on the complexity of the table and column definitions.
I have a data anonymization process that takes a production copy of a database and turns it into an anonymized copy by UPDATE-ing some columns.
Some of the tables contain several million rows so instead of UPDATE-ing the columns, which is very log intensive, I went down the way of
SELECT
Id,
CAST('Redacted' AS NVARCHAR(255)) [ColumnRequiringAnonymization]
INTO MyTable_New
FROM MyTable
EXEC sp_rename MyTable, MyTable_old
EXEC sp_rename MyTable_new, MyTable
DROP TABLE MyTable_old
The problem with this approach is that the "new" table no longer has any of the keys, indices and other dependent objects. I have figured out the keys and indices using SPs to generate the DROP and CREATE scripts. The SPs are based on manually written SQL as can be seen e.g. in this answer.
The next problem is that we have a schemabound view on top of this table, which has indices and a full-text index on its own. The number of SPs to generate scripts is growing and I am sure there will be mistakes.
Is there a way to completely script a table/view by using SQL commands only? ie. just like SSMS does when you click "Script table as - CREATE to" but within a stored procedure?
Right-click on the database, select Tasks; there is Generate Scripts there. Just follow prompts or Google for additional information.
I would like to link a MS Access table to a table in PG admin if it is possible for use in a Postgres query. I have searched for an answer but all I can find is answers for listing postgres tables in Access which is almost the opposite of what I want to do.
I want to be able to access the data entered in an access form without having to continually import the data into a table in PG Admin.
I'm not even sure that is possible but any method that is easier than importing the table into PG Admin every day would be useful.
Thanks
Gary
Try the PostgreSQL OGR Foreign Data Wrapper. Its built for spatial data, but it works perfectly well with non-spatial tables. If you have the PostGIS extension installed you will already have it.
https://github.com/pramsey/pgsql-ogr-fdw
There are several examples on that page, but the command
ogr_fdw_info -s <pathToAccessFile> -l <tablename>
will return create server and a create foreign table statements which you can edit as required then run in pgAdmin.
I have created a table, but is not listed on DataStudio 4101(tables node)
I can insert data by sql commands and drop/create the table, but can not find it on the server Database Node, under tables.
Other tables are displayed, but not the new ones I made.
IF you are using DB2 for i, with "system naming" mode, then your tables may have been created in schema QGPL (the General Purpose Library) by default. Your DB2 session would find them by using its "library list", similar to a path list.
Is it possible to JOIN rows from two separate postgres databases?
I am working with system with couple databases in one server and sometimes I really need such a feature.
According to http://wiki.postgresql.org/wiki/FAQ
There is no way to query a database other than the current one.
Because PostgreSQL loads database-specific system catalogs, it is
uncertain how a cross-database query should even behave.
contrib/dblink allows cross-database queries using function calls. Of
course, a client can also make simultaneous connections to different
databases and merge the results on the client side.
EDIT: 3 years later (march 2014), this FAQ entry has been revised and is more helpful:
How do I perform queries using multiple databases?
There is no way to directly query a database other than the current
one. Because PostgreSQL loads database-specific system catalogs, it is
uncertain how a cross-database query should even behave.
The SQL/MED support in PostgreSQL allows a "foreign data wrapper" to
be created, linking tables in a remote database to the local database.
The remote database might be another database on the same PostgreSQL
instance, or a database half way around the world, it doesn't matter.
postgres_fdw is built-in to PostgreSQL 9.3 and includes read/write
support; a read-only version for 9.2 can be compiled and installed as
a contrib module.
contrib/dblink allows cross-database queries using function calls and
is available for much older PostgreSQL versions. Unlike postgres_fdw
it can't "push down" conditions to the remote server, so it'll often
land up fetching a lot more data than you need.
Of course, a client can also make simultaneous connections to
different databases and merge the results on the client side.
Forget about dblink!
Say hello to Postgres_FDW:
To prepare for remote access using postgres_fdw:
Install the postgres_fdw extension using CREATE EXTENSION.
Create a foreign server object, using CREATE SERVER, to represent each remote database you want to connect to. Specify connection
information, except user, and password, as options of the server
object.
Create a user mapping, using CREATE USER MAPPING, for each database user you want to allow to access each foreign server. Specify
the remote user name and password to use as user and password options
of the user mapping.
Create a foreign table, using CREATE FOREIGN TABLE or IMPORT FOREIGN SCHEMA, for each remote table you want to access. The columns
of the foreign table must match the referenced remote table. You can,
however, use table and/or column names different from the remote
table's, if you specify the correct remote names as options of the
foreign table object.
Now you need only SELECT from a foreign table to access the data
stored in its underlying remote table.
It's really useful even on large data.
Yes, it is possible to do this using dblink albeit with significant performance considerations.
The following example will require the current SQL user to have permissions on both databases. If db2 is not located on the same cluster, then you will need to replace dbname=db2 with the full connection string defined in the dblink documentation.
SELECT *
FROM table1 tb1
LEFT JOIN (
SELECT *
FROM dblink('dbname=db2','SELECT id, code FROM table2')
AS tb2(id int, code text);
) AS tb2 ON tb2.column = tb1.column;
If table2 is very large, you could have performance issues because the sub-query loads up the entire table2 before performing the join.
No you can't. You could use dblink to connect from one database to another database, but that won't help if you're looking for JOIN's.
You can't use different SCHEMA's within a single database to store all you data?
Just a few steps and You can reach the goal:
follow this reference step by step
WE HAVE BEEN CONNECTED TO DB2 WITH TABLE TBL2 AND COLUMN COL2
ALSO THERE IS DB1 WITH TBL1 AND COLUMN COL1
*** connecting to second db ie db2
Now just **copy paste the 1-7 processes** (make sure u use correct username and password and ofcourse db name)
1.**CREATE EXTENSION dblink;**
2.**SELECT pg_namespace.nspname, pg_proc.proname
FROM pg_proc, pg_namespace
WHERE pg_proc.pronamespace=pg_namespace.oid
AND pg_proc.proname LIKE '%dblink%';**
3.**SELECT dblink_connect('host=localhost user=postgres password=postgres dbname=db1');**
4.**CREATE FOREIGN DATA WRAPPER postgres VALIDATOR postgresql_fdw_validator;**
5.**CREATE SERVER postgres2 FOREIGN DATA WRAPPER postgres OPTIONS (hostaddr '127.0.0.1', dbname 'db1');**
6.**CREATE USER MAPPING FOR postgres SERVER postgres2 OPTIONS (user 'postgres', password 'postgres');**
7.**SELECT dblink_connect('postgres2');**
---Now, you can SELECT the data of Database_One from Database_Two and even join both db results:
**SELECT * FROM public.dblink
('postgres2','SELECT col1,um_name FROM public.tbl1 ')
AS DATA(um_userid INTEGER),tbl2 where DATA.col1=tbl2.col2;**
You can also Check this :[How to join two tables of different databases together in postgresql [\[working finely in version 9.4\]][1]
You need to use dblink...as araqnid mentioned above, something like this works fine:
select ST.Table_Name, ST.Column_Name, DV.Table_Name, DV.Column_Name, *
from information_schema.Columns ST
full outer join dblink('dbname=otherdatabase','select Table_Name,
Column_Name from information_schema.Columns') DV(Table_Name text,
Column_Name text)
on ST.Table_Name = DV.Table_name
and ST.Column_Name = DV.Column_Name
where ST.Column_Name is null or DV.Column_Name is NULL
You have use dblink extension of postgresql.
Reference take from this Article:
DbLink extension of PostgreSQL which is used to connect one database to another database.
Install DbLink extension.
CREATE EXTENSION dblink;
Verify DbLink:
SELECT pg_namespace.nspname, pg_proc.proname
FROM pg_proc, pg_namespace
WHERE pg_proc.pronamespace=pg_namespace.oid
AND pg_proc.proname LIKE '%dblink%';
I have already prepared full demonstration on this. Please visit my post to learn step by step for executing cross database query in Postgresql.
Cannot be done? Of course we can, without special extensions. In our case, we had to compare two tables from different database servers, e.g. ACC and PROD, hence an even harder case than from most answers. Especially because ACC and PROD are deliberately on different servers to create a barrier, so you will not easily gain enough rights to perform a GRANT USAGE ON FOREIGN SERVER.
The obvious solution is to export both tables, and import both in the same database, e.g. DEV, or your own local db, under appropriate names, e.g. table1_acc and table1_prod, or schemas like acc and prod. Then, you may JOIN those with no special problems.