So, I am working with redshift and SQL for the first time. I have run into this problem due to my limted knowledge of SQL.
I have this first query which return me tables with the columnA. (TableX, TableY... etc)
SELECT tablename
FROM PG_TABLE_DEF
WHERE ("column" = 'columnA');
Also I have this second query which returns me all the rows from the table containig certain value of columnA.
SELECT *
FROM TableX
WHERE columnA='123934'
What I want to achieve is take the result from the first query which is list of tables, and for each table run the second query i.e. get the rows with value of columnA=123934 for each table returned from first query.
What you want to achieve is done using dynamic SQL. Dynamic queries let you run a query from a string.
I am not an Redshit user but to generate the SQL string you need to run you could use the following query:
SELECT 'SELECT * FROM '||tablename ||' WHERE ColumnA= ''123934''; '
FROM PG_TABLE_DEF
WHERE ("column" = 'columnA');
You can try running it manually.
Related
I want to select rows based on a column value. I know for a fact the column value exists. The first query returns 100 rows from the listing table. The second query, which looks for listings.OriginatingSystemName = 'mfrmls` returns nothing. Why?
(Removing the quotes or using double quotes does not work).
I am using pgAdmin4 to run these queries.
first query:
select * from listing limit 100;
second query:
select * from listing where 'listing.OriginatingSystemName' = 'mfrmls'
This produces a 'column does not exist' error:
select * from listing where OriginatingSystemName = 'mfrmls'
The correct syntax is to just write the column name in your WHERE statement:
SELECT * FROM listings WHERE "OriginatingSystemName" = 'mfrmls';
To elaborate further:
What your original query is doing is selecting every row in the listings table where the text string 'listings.OriginatingSystemName' is equal to this other text string 'mfrmls'. It is not actually grabbing the value from the column you want. No row in the table satisfies your where statement because your where statement is always false. Therefore, no rows are returned but the query was a success.
We need to implement the double quotes when dealing with case-sensitive identifiers. Here is some helpful documentation.
I have an interesting problem from work. I have an Oracle procedure written by someone else that returns a dataset (multi-column, multi-row) for a single input person ID. I need to use this procedure to get the dataset for all person IDs.
The procedure can be queried by casting the output as a table:
"select * from table (package.proc(in_ID))"
The only way I know how to query this is to make multiple proc calls like this:
select ID,
(select col1 from table(package.proc(persons.ID)) as col1,
(select col2 from table(package.proc(persons.ID)) as col2, --(etc...)
from persons
However, for the number of rows and columns I need to get from this thing, this is terribly inefficient and causes server timeouts. Also, the subselects can only get one row from the proc so I also have missing rows (or if it returns more than one row it errors on the subselect).
Is there a way to do this that doesn't involve rewriting the procedure to return the data for all person IDs?
Starting from Oracle 12c you could use CROSS/OUTER APPLY:
SELECT *
FROM persons p
OUTER APPLY(TABLE(package.proc(p.ID))) s;
I want to get the sequence for the id column in the tags table as
SELECT pg_get_serial_sequence(‘tags’, ‘id’);
And then I want to use the result from the above Query (the sequence) as an input to the second query. Let s say the first query is called sequence
I want to perform the second query as:
SELECT setval(**sequence**, SELECT max(id) FROM tags);
Any idea on how to do this ?
You can use ActiveRecord::Base.connection.execute("your SQL query here").
I have these queries:
SELECT *
FROM dbo.GRAUD_ProjectsByCostCategory
select right(CostCategoryId,14) as CostBreak
from dbo.GRAUD_ProjectsByCostCategory
They work well in that they give me the correct data, but I would like to know how to combine the new column CostBreak into the table of results rather than as a separate query result.
An example of the results I get are as below:
Where I want them in the same table
The data is coming from the same table so you should be able to just add that value to your initial query. You do not even have to perform a join to get it:
SELECT name,
description,
project,
CostCategoryId,
right(CostCategoryId,14) as CostBreak
FROM dbo.GRAUD_ProjectsByCostCategory
My stored procedure (SQL Server 2005) returns a dataset where one field depends, among other things, on the number of rows returned by the query. I can make a simplified first query that allows me to get ##ROWCOUNT but, in that case, the procedure returns the two sets, which is not what I want.
I tried putting the first query in a WITH statement but haven't found the syntax to extract the row count and put it in a variable that I could use in the second query. An alternative would be to get ##ROWCOUNT from the first query and tell the procedure to return only the result of the second query.
There are probably better ways to do that but my expertise in SQL is quite limited...
Thanks for any help!
Is this what you're looking for? If not, could you please describe your problem in more details (perhaps, with code snippets)
alter procedure ComplicatedStoredProcedure as
begin
declare #lastQueryRowCount int
-- Storing the number of rows returned by the first query into a variable.
select #lastQueryRowCount =
-- First resultset (not seen by caller).
(select count(*) from A where ID > 100)
-- Second resultset. This will be the actual result returned from the SP.
select * from B where SomeDependentField > #lastQueryRowCount
end