I have a stored procedure that is performing two different queries. When the stored procedure is complete I see both result sets. Is there a way to suppress the first result set, and only have the second one display without combining the information?
select info
from table
where (select * from othertable)
This statement causes me to end up with two different result sets. I want to suppress the results from the "othertable" query.
Is this possible?
Note: This is the answer, but not the answer. While going over #Jeroen's response I decided to go into my sproc and include more information in the original post. Upon doing that I came across a "stray" select statement I was using in conjunction with print for debugging purposes. I commented out that line and the additional result set went away. Problem solved! Thank you #Jeoroen!!
Related
I need to replace all occurrences "google.com" that are met in the SQL db table Column1 with "newurl". It can be a full cell value, a part of it (substring of varchar()), can be met even several times in a cell.
Based on SO answer search-and-replace-part-of-string-in-database
this is what I need:
UPDATE
MyTable
SET
Column1 = Replace(Column, 'google.com', 'newurl')
WHERE
xxx
However, in that answer it is mentioned that
You will want to be extremely careful when doing this! I highly recommend doing a backup first.
What are the pitfalls of doing this query? Looks like it does the same what any texteditor would do by clicking on Replace All button. I don't think it is possible in my case to check the errors even with reserve copy as I would like to know possible errors in advance.
Any reasons to be careful with this query?
Again, I expect it replaces all occurences of google.com with 'newurl' in the Column1 of MyTable table in the SQL db.
Thank you.
Just create a test table, as a replica of your original source table, complete the update on there and check results.
You would want to do this as good SQL programming practice to ensure you don't mess up columns that should not be updated.
Another thing you can do is get a count of the records before hand that fit the criteria using a SELECT statement.
Run your update statement and if it's a 1-1 match on count, you should be good to go.
The only thing i can think of that would happen negatively in this respect is that additional columns get updated. Your WHERE clause is not specific for us to see, so there's no way to validate that what you're doing will do what you expect it to.
I think the person posting the answer is just being cautious - This will modify the value in Column1 for every row in MyTable, so make sure you mean it when you execute. Another way to be cautious would be to wrap it in a transaction so you could roll it back if you don't like the results.
I want write a query with active record and seems it never respect what I want to do. So, here are my example:
Phonogram.preload(:bpms).includes(:bpms).select("phonograms.id", "bpms.bpm")
This query returns all my fields from phonograms and bpms. The problem is that I need put more 15 relationships in this query.
I also tried use joins but didn't work properly. I've 10 phonograms and returns just 3.
Someone experienced that? How did you solve it properly?
Cheers.
select with includes does not produce consistent behavior. It appears that if the included association returns no results, select will work properly, if it returns results, the select statement will have no effect. In fact, it will be completely ignored, such that your select statement could reference invalid table names and no error would be produced. select with joins will produce consistent behavior.
That's why you better go with joins like:
Phonogram.joins(:bpms).select("phonograms.id", "bpms.bpm")
Need help. This problem blowed my mind.
My problems is almost the same as in the question Lookup values in one table and add to dataset according to IF condition (MERGE/SQL)?
I am using one of the code from answers:
proc sql;
update master as a
set loadport=(select loadport from lookup as b
where a.LoadCountry=b.LoadCountry and a.LoadArea=b.LoadArea)
where lportmiss=1;
quit;
However I faced with error "Subquery evaluated to more than one row". As far as I find out it means that there are more than one loadports with equal loadports name in lookup dataset and sql does not know which one to choose.
My question is what refinements should be made to choose first met loadport in lookup dataset?
Thanks!
Something like this will work. You need to use a summary function to reduce to one row. If you're confident one loadCountry/loadArea combination will always have only one port, this is safe; if you're not, then you need to think about how to do this properly (whether max or min is okay, or if you need to flag an error or something else if this happens). Almost any summary function will do here.
proc sql;
update master as a
set loadport=(select max(loadport) from lookup as b
where a.LoadCountry=b.LoadCountry and a.LoadArea=b.LoadArea
group by b.loadCountry,b.loadArea)
where lportmiss=1;
quit;
I am wondering how others would handle a scenario like such:
Say I have multiple choices for a user to choose from.
Like, Color, Size, Make, Model, etc.
What is the best solution or practice for handling the build of your query for this scneario?
so if they select 6 of the 8 possible colors, 4 of the possible 7 makes, and 8 of the 12 possible brands?
You could do dynamic OR statements or dynamic IN Statements, but I am trying to figure out if there is a better solution for handling this "WHERE" criteria type logic?
EDIT:
I am getting some really good feedback (thanks everyone)...one other thing to note is that some of the selections could even be like (40 of the selections out of the possible 46) so kind of large. Thanks again!
Thanks,
S
What I would suggest doing is creating a function that takes in a delimited list of makeIds, colorIds, etc. This is probably going to be an int (or whatever your key is). And splits them into a table for you.
Your SP will take in a list of makes, colors, etc as you've said above.
YourSP '1,4,7,11', '1,6,7', '6'....
Inside your SP you'll call your splitting function, which will return a table-
SELECT * FROM
Cars C
JOIN YourFunction(#models) YF ON YF.Id = C.ModelId
JOIN YourFunction(#colors) YF2 ON YF2.Id = C.ColorId
Then, if they select nothing they get nothing. If they select everything, they'll get everything.
What is the best solution or practice for handling the build of your query for this scenario?
Dynamic SQL.
A single parameter represents two states - NULL/non-existent, or having a value. Two more means squaring the number of parameters to get the number of total possibilities: 2 yields 4, 3 yields 9, etc. A single, non-dynamic query can contain all the possibilities but will perform horribly between the use of:
ORs
overall non-sargability
and inability to reuse the query plan
...when compared to a dynamic SQL query that constructs the query out of only the absolutely necessary parts.
The query plan is cached in SQL Server 2005+, if you use the sp_executesql command - it is not if you only use EXEC.
I highly recommend reading The Curse and Blessing of Dynamic SQL.
For something this complex, you may want a session table that you update when the user selects their criteria. Then you can join the session table to your items table.
This solution may not scale well to thousands of users, so be careful.
If you want to create dynamic SQL it won't matter if you use the OR approach or the IN approach. SQL Server will process the statements the same way (maybe with little variation in some situations.)
You may also consider using temp tables for this scenario. You can insert the selections for each criteria into temp tables (e.g., #tmpColor, #tmpSize, #tmpMake, etc.). Then you can create a non-dynamic SELECT statement. Something like the following may work:
SELECT <column list>
FROM MyTable
WHERE MyTable.ColorID in (SELECT ColorID FROM #tmpColor)
OR MyTable.SizeID in (SELECT SizeID FROM #tmpSize)
OR MyTable.MakeID in (SELECT MakeID FROM #tmpMake)
The dynamic OR/IN and the temp table solutions work fine if each condition is independent of the other conditions. In other words, if you need to select rows where ((Color is Red and Size is Medium) or (Color is Green and Size is Large)) you'll need to try other solutions.
I use PostgreSQL database and C to connect to it. With a help from dyntest.pgc I can access to number of columns and their (SQL3) types from a result table of a query.
Problem is that when result table is empty, I can't fetch a row to get this data. Does anyone have a solution for this?
Query can be SELECT 1,2,3 - so, I think I can't use INFORMATION SCHEMA for this because there is no base table.
I'm not familiar with ecpg, but with libpq you should be able to call PQnfields to get the number of fields and then call various PQf* routines (like PQftype, PQfname) to get detailed info. Those functions take a PGResult, which you have even if there are no rows.
Problem is that when result table is empty, I can't fetch a row to get this data. Does anyone have a solution for this?
I am not sure to really get what you want, but it seems the answer is in the question. If the table is empty, there are no rows...
The only solution here seems you must wait a non empty result table, and then get the needed informations.