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.
Related
I have a parent table (parent_table) and few children tables inherit from it (child_one_table and child_two_table).
I want to query data using columns belong to the parent table only (the data itself is inserted to the children tables), when I run an explain on my query I see that there are sequence scans running on all the tables (parent_table, child_one_table and child_two_table).
Is there a more efficient way to do this? When I try to query using ONLY on parent_table I get back 0 result since the data was inserted to children table.
Thanks in advance!
Thanks for clarifying your question!
When I query the data for SELECT * FROM parent_table WHERE name = 'joe'; I see that it actually go over all 3 tables and query for that.
This seems to be standard behaviour from PostgreSQL. According to the 5.10.1. Caveats section of https://www.postgresql.org/docs/current/ddl-inherit.html
Note that not all SQL commands are able to work on inheritance hierarchies. Commands that are used for data querying, data modification, or schema modification (e.g., SELECT, UPDATE, DELETE, most variants of ALTER TABLE, but not INSERT or ALTER TABLE ... RENAME) typically default to including child tables and support the ONLY notation to exclude them.
So really what you want to do is explore the usage of ONLY to specify the scope of your query.
I hope this can help!
How to get the name of the schema, tables and primary keys?
How to know his authorizations?
The only information I have is obtained by the command below:
db2 => connect
Database Connection Information
Database server = DB2/AIX64 11.1.3.3
SQL authorization ID = mkrugger
Local database alias = DBRCF
You can use the command line (interactive command line processor), if you want, but if you are starting out then it is easier to use a GUI tool.
Example free GUI, IBM Data Studio, and there are many more (any GUI that works with JDBC should work with Db2 on Linux/Unix/Windows). These are easy to find online and download if you are permitted.
To use the Db2 command-line (clp) which is what you show in your question,
Example command lines:
list tables for all
list tables for user
list tables for schema ...
describe table ...
describe indexes for table ...
Reference for LIST TABLES command
You can also use plain SQL to read the catalog views, which describes the schemas, tables, primary keys as a series of views.
Look in the online free documentation for details of views like SYSCAT.TABLES, SYSCAT.COLUMNS , SYSCAT.INDEXES and hundreds of other views.
Depending on which Db2 product is installed locally, there are a range of other command-line based tools. One in particular is db2look which lets you extract all of the DDL of the database (or a subset of it) into a plain text file if you prefer that.
What is the difference between these two queries:
select * from syscat.tabauth
select * from sysibm.systabauth where tcreator='SYSCAT' and ttname='TABAUTH'
Are they same ?
EDIT:
1. select grantee from sysibm.systabauth where tcreator='SYSCAT' and ttname='TABAUTH' and selectauth='Y'
select grantee from syscat.tabauth where selectauth='Y'
Would there be any difference in the value of these two queries ???
If I change selectauth to 'N' using sysibm.systabauth. Does that reflect in query 2?
The main difference is that one is a table and the other is a readonly view.
Other differences exist, and they can be version specific.
Different permissions can apply also.
When your target database are always on Linux/Unix/Windows , use SYSCAT schema as IBM tries to keep that unchanged even if the underlying objects change between versions (except where new columns get added ). IBM describes the SYSCAT schema here.
The SYSCAT schema contains many views and is relevant for Linux/Unix/Windows versions of Db2-Servers.
The SYSIBM schema contains many tables and is present on both Z/OS and LUW versions of Db2-servers.
So SYSCAT.TABAUTH is only a view on SYSIBM.SYSTABAUTH and you can see the definition of the view in the catalog with a query like this:
"select substr(text,1,4096) from syscat.views where viewschema='SYSCAT' and viewname='TABAUTH'"
You use GRANT and REVOKE statements to alter the contents of the SYSIBM.TABAUTH table directly, other statements like CREATE/DROP/ALTER table can indirectly change its contents.
I have an Access query, which references a table: dbo_table2
However, I have moved this table to another database, so I need to fully qualify to restore the links.
SELECT table1.x, table1.y, table2.z
FROM dbo_table1
INNER JOIN dbo_table2
ON (dbo_ID = dbo_ID)
Both tables are being pulled from SQL tables.
In my Access query I have added table2 as a Linked Table.
But I'm unsure of Access syntax. If I was using SQL, I would simply use "newdatabaseDB.dbo.table2".
My question is how can I correctly name the table2 reference by fully qualifying the database and table name.
If you moved your table to another db, just Link that table in your current db. This way you can use just as it was local.
There is another option, using IN:
select * from clients in 'c:\test\mydb.mdb'
Also see https://stackoverflow.com/a/3123395/78522
Cracked it!
By creating a link to an external table in the database where the query was created, Access then treats the table in the queries as if it were local (so no fully qualification needed).
What I am trying to do is verify a URL. I just need to be able to select that single value from all databases that we have currently in SQL Server 2008. All the databases are the same, just multiple instances of the same database for different users.
I am looking to pull one item from one table in each database.
Each database contains a table SETTINGS and within that table a value for MapIconURL. I need that value from each table from within each database. I am looking at around 30 or so databases that would have this value.
So I found the "undocumented" Stored Proc sp_MsForEachDb and have working....to a point.
The code I am using is this:
EXEC sp_MsForEachDb 'use ?; SELECT "?" as databasename,SETTINGSKEYID, SECTION, NAME, INIVALUE, DESCRIPTION
FROM ?.dbo.SETTINGS
WHERE [NAME] = "MapIconURL"'
I have noticed that it is not selecting all the databases, but that it is also selecting the master table as well as other system tables, and am thinking that may be why it is not selecting all tables. Is there a way to exclude the system related tables?
If the number (and name) of the databases is fixed, then you could simply do:
SELECT MapIconUrl FROM db1.dbo.SETTINGS
UNION ALL
SELECT MapIconUrl FROM db2.dbo.SETTINGS
...
However, if either the number or names of the databases is not fixed, then you have to build the query dynamically.
First, run a query such as SELECT name FROM master..sysdatabases to get the names of the databases.
Then, loop over the result set (in T-SQL, use a CURSOR) and build your query and execute it (in T-SQL, use sp_executesql).