Is there a lightweight sql statement that I can against an oracle database to test if the database is up, available and able to exceute sql?
SELECT 1
FROM dual
is a common one. You could select any constant value from DUAL as well.
If you don't want to connect first, you could query through a link, for example, I have a set of links to an external system and I run SQL of the following form:
select * from global_name#myLink01.WORLD;
If you write the sql statement to describe dual table, then also you will get to know it whether db is up and running.
desc dual;
Related
I am writing a performance/system monitoring tool to augment load testing for my team's product and I am trying to store database system information with the results bundle but do not know how to write the query to capture this in Oracle (I'm a developer not a DBA).
I have this all working the way I want for SQL Server, but I need to do the same for Oracle. Below is a query I found online for this is SQL Server:
SELECT CONVERT(varchar(128),SERVERPROPERTY('ComputerNamePhysicalNetBIOS')) AS 'computerNamePhysicalNetBIOS',
CONVERT(varchar(128),SERVERPROPERTY('MachineName')) AS 'machineName',
CONVERT(varchar(128),SERVERPROPERTY('Edition')) AS 'edition',
CONVERT(varchar(128),SERVERPROPERTY('ProductLevel')) AS 'productLevel',
CONVERT(varchar(128),SERVERPROPERTY('ProductVersion')) AS 'productVersion',
CONVERT(varchar(128),SERVERPROPERTY('BuildClrVersion')) AS 'buildClrVersion',
CONVERT(INT,SERVERPROPERTY('ProcessID')) AS 'processID',
CONVERT(INT,SERVERPROPERTY('EngineEdition')) AS 'engineEdition',
CONVERT(INT,SERVERPROPERTY('HadrManagerStatus')) AS 'hadrManagerStatus',
CONVERT(INT,SERVERPROPERTY('IsHadrEnabled')) AS 'hadrEnabled',
CONVERT(INT,SERVERPROPERTY('IsAdvancedAnalyticsInstalled')) AS 'advancedAnalyticsInstalled',
CONVERT(INT,SERVERPROPERTY('IsClustered')) AS 'clustered',
CONVERT(INT,SERVERPROPERTY('IsPolybaseInstalled')) AS 'polybaseInstalled',
CONVERT(INT,SERVERPROPERTY('IsXTPSupported')) AS 'xtpSupported',
CONVERT(INT,SERVERPROPERTY('LCID')) AS 'lcid',
CONVERT(varchar(128),SERVERPROPERTY('ResourceVersion')) AS 'resourceVersion',
CONVERT(varchar(128),SERVERPROPERTY('ServerName')) AS 'serverName',
CONVERT(varchar(128),APP_NAME() )AS 'appName',
CONVERT(INT,DB_ID()) AS 'dbId',
CONVERT(varchar(128),DB_NAME()) AS 'dbName'
I don't really expect a one-to-one column match between the above query and Oracle's version, but in general, how can I get very similar information from Oracle?
I don't really expect a one-to-one column match between the above
query and Oracle's version, but in general, how can I get very similar
information from Oracle?
Most of that stuff, if it exists at all in the Oracle database, will be accessible through V$ views in the Oracle database. To get you started, here are some that are going to be most relevant to answering your question:
select * from v$instance;
select * from v$version;
select * from v$sql_feature;
select * from v$license;
select * from v$option;
If you want to get a complete list of V$ views to look around better,
select * from dict where table_name like 'V$%';
Some of those things are specific to MSSQL and have no meaning in Oracle. But you can get many of them with sys_context() using the userenv namespace.
For instance, to get the database name:
select sys_context('userenv', 'DB_NAME') as db_name
from dual;
Platform: SQL Server 2008
Language: TSQL
I have a number of queries that currently take the general form of (for simplicity sake)
-- Sample begin results
SELECT * from DB01.dbo.table UNION ALL
SELECT * from DB02.dbo.table UNION ALL --many other databases follow with same syntax
How can I modify these queries such that, when a new database comes into existence (named, say DB39C), I ensure that my queries already includes those new records?
--Sample end results
SELECT * from DB01.dbo.table UNION ALL
SELECT * from DB02.dbo.table UNION ALL
SELECT * from DB39C.dbo.table -- this was created as soon as a new database came into existence
I am looking to make sure programmatically, that this happens without my awareness as new databases are added quite regularly and I need the queries I rely on to keep pace.
You might want to have a look at using something like
SELECT name AS DATABASENAME
FROM master.dbo.sysdatabases
and creating dynamic queries
sys.databases (Transact-SQL)
I need a common select statement that returns a fixed value / row without the need of tables, which has to work with both Oracle & Sql Server.
eg for Oracle I know I can use:
select 'O' AS INDICATOR from DUAL;
But this won't work on Sql Server.
Can this be done with the same SQL on both Oracle & SQL Server?
AFAIK, you'll need different queries, unless you can find a table that exists both on the SQL Server and on the Oracle Server.
Oracle uses the DUAL table for dummy queries, while the syntax to just select a constant on SQL server is a bit simpler:
select 'O' as Indicator
will return a one-row recordset.
P.S. If you intend to write just standard SQL and have it work on both SQL Server and Oracle, note that there are lots and lots of differences, even if you do not use database-side code (stored procedures and functions).
Off the top of my head, some things that are different:
Case statement syntax
NVL vs IsNull
Null sorting behaviour
Data conversion functions
String manipulation functions
etc, etc.
You can't select data in Oracle without from statement. So you need to have a table in Oracle (common practice is to use standard table - Dual). The best solution if you really need to run same query on both database servers is to create Dual table with only one row in MS SQL. But really it's better to use different queries for different servers (maybe via some abstraction layer).
Use a common table expression (CTE) e.g.
WITH D (INDICATOR)
AS
(
SELECT *
FROM (
VALUES ('O')
) T (c1)
)
SELECT INDICATOR
FROM D;
Or more simply in line:
SELECT *
FROM (
VALUES ('O')
) D (INDICATOR)
You can create the DUAL table in SQL Server:
CREATE TABLE DUAL (DUMMY NVARCHAR(1) NOT NULL);
INSERT INTO DUAL VALUES ('X');
and then use the same query as in Oracle:
select 'O' AS INDICATOR from DUAL;
I need to test the connection to a db2 database.
With oracle databases I'd execute a 'select * from dual' in order to do this.
But dual is specific for oracle. Is there a similar canonical test sql statement for db2?
SELECT 1 FROM SYSIBM.SYSDUMMY1
cheaper then
SELECT CURRENT SQLID FROM SYSIBM.SYSDUMMY1
I ended up using
SELECT CURRENT SQLID FROM SYSIBM.SYSDUMMY1
which seems to work nice.
LIST DB DIRECTORY
or
LIST TABLES
I'm looking for a simple DB2 query that can be used to test if a database connection in pool is still valid. It needs to be a generic query that would execute regardless of which databases exist.
For other database servers, I've used something like 'SELECT 1' or 'SELECT version();'
What would be an equivalent for DB2?
Thanks!
Try values 1.
Also, you can get the current date as
VALUES current date
or
SELECT current date FROM sysibm.sysdummy1
You can also get the version info as follows
SELECT service_level, fixpack_num, bld_level
FROM TABLE (sysproc.env_get_inst_info()) as A;