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  • Subquery vs Traditional join with WHERE clause?

    - by BradC
    When joining to a subset of a table, any reason to prefer one of these formats over the other? Subquery version: SELECT ... FROM Customers AS c INNER JOIN (SELECT * FROM Classification WHERE CustomerType = 'Standard') AS cf ON c.TypeCode = cf.Code INNER JOIN SalesReps s ON cf.SalesRepID = s.SalesRepID vs the WHERE clause at the end: SELECT ... FROM Customers AS c INNER JOIN Classification AS cf ON c.TypeCode = cf.Code INNER JOIN SalesReps AS s ON cf.SalesRepID = s.SalesRepID WHERE cf.CustomerType = 'Standard' The WHERE clause at the end feels more "traditional", but the first is arguably more clear, especially as the joins get increasingly complex. Only other reason I can think of to prefer the second is that the "SELECT *" on the first might be returning columns that aren't used later (In this case, I'd probably only need to return cf.Code and Cf.SalesRepID)

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  • ORA-00937 error during select subquery

    - by RedRaven
    I am attempting to write a query that returns the the number of employees, the average salary, and the number of employees paid below the average. The query I have so far is: select trunc(avg(salary)) "Average Pay", count(salary) "Total Employees", ( select count(salary) from employees where salary < (select avg(salary) from employees) ) UnderPaid from employees; But when I run this I get the ora-00937 error in the subquery. I had thought that maybe the "count" function is what is causing the issue, but even running a simpler sub query such as: select trunc(avg(salary)) "Average Pay", count(salary) "Total Employees", ( select avg(salary) from employees ) UnderPaid from employees; still returns the same error. As both AVG and COUNT seem to be aggregate functions, I'm not sure why I'm getting the error? Thanks

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  • Performance: Subquery or Joining

    - by Auro
    Hello I got a little question about performance of a subquery / joining another table INSERT INTO Original.Person ( PID, Name, Surname, SID ) ( SELECT ma.PID_new , TBL.Name , ma.Surname, TBL.SID FROM Copy.Person TBL , original.MATabelle MA WHERE TBL.PID = p_PID_old AND TBL.PID = MA.PID_old ); This is my SQL, now this thing runs around 1 million times or more. Now my question is what would be faster? if I change TBL.SID to (Select new from helptable where old = tbl.sid) or if I add helptable to the from and do the joining in the where? greets Auro

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  • Outer select column value in joined subquery?

    - by Michael DePetrillo
    Is it possible to use a column value from an outer select within a joined subquery? SELECT table1.id, table2.cnt FROM table1 LEFT JOIN (SELECT COUNT(*) as `cnt` FROM table2 where table2.lt > table1.lt and table2.rt < table1.rt) as table2 ON 1; This results in "Unknown column 'table1.lt' in 'where clause'". Here is the db dump. CREATE TABLE IF NOT EXISTS `table1` ( `id` int(1) NOT NULL, `lt` int(1) NOT NULL, `rt` int(4) NOT NULL) ENGINE=MyISAM DEFAULT CHARSET=latin1; CREATE TABLE IF NOT EXISTS `table2` ( `id` int(1) NOT NULL, `lt` int(1) NOT NULL, `rt` int(4) NOT NULL) ENGINE=MyISAM DEFAULT CHARSET=latin1; INSERT INTO `table1` (`id`, `lt`, `rt`) VALUES (1, 1, 4); INSERT INTO `table2` (`id`, `lt`, `rt`) VALUES (2, 2, 3);

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  • Beautifulsoup recursive attribute

    - by Marcos Placona
    Hi, trying to parse an XML with Beautifulsoup, but hit a brick wall when trying to use the "recursive" attribute with findall() I have a pretty odd xml format shown below: <?xml version="1.0"?> <catalog> <book id="bk101"> <author>Gambardella, Matthew</author> <title>XML Developer's Guide</title> <genre>Computer</genre> <price>44.95</price> <publish_date>2000-10-01</publish_date> <description>An in-depth look at creating applications with XML.</description> <catalog>true</catalog> </book> <book id="bk102"> <author>Ralls, Kim</author> <title>Midnight Rain</title> <genre>Fantasy</genre> <price>5.95</price> <publish_date>2000-12-16</publish_date> <description>A former architect battles corporate zombies, an evil sorceress, and her own childhood to become queen of the world.</description> <catalog>false</catalog> </book> </catalog> As you can see, the catalog tag repeats inside the book tag, which causes an error when I try to to something like: from BeautifulSoup import BeautifulStoneSoup as BSS catalog = "catalog.xml" def open_rss(): f = open(catalog, 'r') return f.read() def rss_parser(): rss_contents = open_rss() soup = BSS(rss_contents) items = soup.findAll('catalog', recursive=False) for item in items: print item.title.string rss_parser() As you will see, on my soup.findAll I've added recursive=false, which in theory would make it no recurse through the item found, but skip to the next one. This doesn't seem to work, as I always get the following error: File "catalog.py", line 17, in rss_parser print item.title.string AttributeError: 'NoneType' object has no attribute 'string' I'm sure I'm doing something stupid here, and would appreciate if someone could give me some help on how to solve this problem. Changing the HTML structure is not an option, this this code needs to perform well as it will potentially parse a large XML file. Thanks in advance, Marcos

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  • Return pre-UPDATE column values in PostgreSQL without using triggers, functions or other "magic"

    - by Python Larry
    I have a related question, but this is another part of MY puzzle. I would like to get the OLD VALUE of a Column from a Row that was UPDATEd... WITHOUT using Triggers (nor Stored Procedures, nor any other extra, non-SQL/-query entities). The query I have is like this: UPDATE my_table SET processing_by = our_id_info -- unique to this instance WHERE trans_nbr IN ( SELECT trans_nbr FROM my_table GROUP BY trans_nbr HAVING COUNT(trans_nbr) > 1 LIMIT our_limit_to_have_single_process_grab ) RETURNING row_id If I could do "FOR UPDATE ON my_table" at the end of the subquery, that'd be devine (and fix my other question/problem). But, that won't work: can't have this AND a "GROUP BY" (which is necessary for figuring out the COUNT of trans_nbr's). Then I could just take those trans_nbr's and do a query first to get the (soon-to-be-) former processing_by values. I've tried doing like: UPDATE my_table SET processing_by = our_id_info -- unique to this instance FROM my_table old_my_table JOIN ( SELECT trans_nbr FROM my_table GROUP BY trans_nbr HAVING COUNT(trans_nbr) > 1 LIMIT our_limit_to_have_single_process_grab ) sub_my_table ON old_my_table.trans_nbr = sub_my_table.trans_nbr WHERE my_table.trans_nbr = sub_my_table.trans_nbr AND my_table.processing_by = old_my_table.processing_by RETURNING my_table.row_id, my_table.processing_by, old_my_table.processing_by But that can't work; "old_my_table" is not viewable outside of the join; the RETURNING clause is blind to it. I've long since lost count of all the attempts I've made; I have been researching this for literally hours. If I could just find a bullet-proof way to lock the rows in my subquery - and ONLY those rows, and WHEN the subquery happens - all the concurrency issues I'm trying to avoid disappear... UPDATE: [WIPES EGG OFF FACE] Okay, so I had a typo in the non-generic code of the above that I wrote "doesn't work"; it does... thanks to Erwin Brandstetter, below, who stated it would, I re-did it (after a night's sleep, refreshed eyes, and a banana for bfast). Since it took me so long/hard to find this sort of solution, perhaps my embarrassment is worth it? At least this is on SO for posterity now... : What I now have (that works) is like this: UPDATE my_table SET processing_by = our_id_info -- unique to this instance FROM my_table AS old_my_table WHERE trans_nbr IN ( SELECT trans_nbr FROM my_table GROUP BY trans_nbr HAVING COUNT(*) > 1 LIMIT our_limit_to_have_single_process_grab ) AND my_table.row_id = old_my_table.row_id RETURNING my_table.row_id, my_table.processing_by, old_my_table.processing_by AS old_processing_by The COUNT(*) is per a suggestion from Flimzy in a comment on my other (linked above) question. (I was more specific than necessary. [In this instance.])

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  • Ordering recursive result set in SQL Server

    - by Ben
    I am having extreme difficulty constructing a query which returns an XML style hierarchy. We have a database table which contains a hierarchy of URLs for our website. The table contains the columns: ID, URL, DisplayName, ParentID, ItemOrder The parent ID forms a recursive relationship between the current item and it's parent. The item should site below it's parent in the hierarchy and it should also be ordered using the item order against items at the same level in the hierarchy. I have managed to get a recursive query working so it drills down the hierarchy sequentially but I cannot order this by the item order as well. My current query is below: WITH Parents AS ( SELECT MenuItemId, URL, ParentItemId, ItemOrder FROM CambsMenu UNION ALL SELECT si.MenuItemId, si.URL, si.ParentItemId, si.ItemOrder FROM CambsMenu si INNER JOIN Parents p ON si.ParentItemId = p.MenuItemId ) SELECT DISTINCT * FROM Parents

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  • recursive program

    - by wilson88
    I am trying to make a recursive program that calculates interest per year.It prompts the user for the startup amount (1000), the interest rate (10%)and number of years(1).(in brackets are samples) Manually I realised that the interest comes from the formula YT(1 + R)----- interest for the first year which is 1100. 2nd year YT(1 + R/2 + R2/2) //R squared 2nd year YT(1 + R/3 + R2/3 + 3R3/) // R cubed How do I write a recursive program that will calculate the interest? Below is the function which I tried double calculateInterest(double startUp, double rate, double duration) { double cpdInterest = (duration*startUp)*(1 + rate); if (duration == 0) { return cpdInterest; } else if (duration < 0) { cout << "Please enter a valid year"; } else { calculateInterest(cpdInterest,rate,duration); } return cpdInterest; }

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  • Updating rows using "in" operator in "where" clause

    - by doublep
    Hi. I stumbled upon SQL behavior I don't understand. I needed to update several rows in a table at once; started with just finding them: SELECT * FROM some_table WHERE field1 IN (SELECT ...) This returned a selection of about 60 rows. Now I was pretty confident I got the subquery right, so I modified the first part only: UPDATE some_table SET field2 = some_value WHERE field1 IN (SELECT ...) In other words, this was exactly as the first query after the WHERE. However, it resulted in 0 rows updated, whereas I would expect those 60. Note that the statement above would change field2, i.e. I verified that some_value was not present in the selected rows. The subquery was a modestly complicated SQL piece with 2 (different) tables, 1 view, joins and its own WHERE clause. In case this matters, it happened with Oracle Database 10g. So, the question is, why UPDATE didn't touch the rows returned by SELECT?

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  • Time Complexities of recursive algorithms

    - by Peter
    Whenever I see a recursive solution, or I write recursive code for a problem, it is really difficult for me to figure out the time complexity, in most of the cases I just say its exponential? How is it exponential actually? How people say it is 2^n, when it is n!, when it is n^n or n^k. I have some questions in mind, let say find all permutations of a string (O(n!)) find all sequences which sum up to k in an array (exponential, how exactly do I calculate). Find all subsets of size k whose sum is 0 (will k come somewhere in complexity , it should come right?). Can any1 help me how to calculate the exact complexity of such questions, I am able to wrote code for them , but its hard understanding the exact time complexity.

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  • recursive program

    - by wilson88
    I am trying to make a recursive program that calculates interest per year.It prompts the user for the startup amount (1000), the interest rate (10%)and number of years(1).(in brackets are samples) Manually I realised that the interest comes from the formula YT(1 + R)----- interest for the first year which is 1100. 2nd year YT(1 + R/2 + R2/2) //R squared 2nd year YT(1 + R/3 + R2/3 + 3R3/) // R cubed How do I write a recursive program that will calculate the interest? Below is the function which I tried //Latest after editing double calculateInterest2(double start, double rate, int duration) { if (0 == duration) { return start; } else { return (1+rate) * calculateInterest2(start, rate, duration - 1); } }

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  • Recursive Functions for Beginners?

    - by cam
    I'm looking for a few recursive function examples, preferably ones that show increase in complexity. I understand basic recursive functions, but I'm having trouble implementing them in my code. I've never used them in my code before, and I know it doesn't always call for it, but I'd like to try. Is there a good resource with examples, and maybe challenges of some sort? Or even some simple math problems (Project Euler-style?) that I could use recursion on? For examples, I prefer C#, but anything works.

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  • Get recursive data with sql server

    - by user228777
    I am trying to get recursive data. Following code returns all parents on the top and then the children. I would like to get data Parent 1 – his children then parent 2 - his children then parent3 – his children. How do I do this? USE Subscriber GO WITH Parent (ParentId, Id, Name,subscriberID) AS ( -- Anchor member definition SELECT A.ParentId,A.id, A.name,A.SubscriberId FROM Subscriber.Budget.SubscriberCategory AS A WHERE ParentId IS NULL UNION ALL -- Recursive member definition SELECT B.ParentId, B.id, B.name,B.SubscriberId FROM Subscriber.Budget.SubscriberCategory AS B INNER JOIN Parent AS P ON B.ParentId = P.Id ) -- Statement that executes the CTE SELECT parentId, id, name FROM Parent where subscriberID = '1C18093B-5031-42E4-9251-CEF69114365F' GO

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  • Are conditional subqueries optimized out, if the condition is false?

    - by Tobias Schulte
    I have a table foo and a table bar, where each foo might have a bar (and a bar might belong to multiple foos). Now I need to select all foos with a bar. My sql looks like this SELECT * FROM foo f WHERE [...] AND ($param IS NULL OR (SELECT ((COUNT(*))>0) FROM bar b WHERE f.bar = b.id)) with $param being replaced at runtime. The question is: Will the subquery be executed even if param is null, or will the dbms optimize the subquery out? We are using mysql, mssql and oracle. Is there a difference between these regarding the above?

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  • What does this recursive function do?

    - by null
    What does this function do? And how do you evaluate it? How to trace it? How to understand recursive method? I just can't understand the recursion, and the exam date is coming soon, and I know in order to understand recursion, I must first understand recursion. But I just can't write a slightly complex recursive method, can anyone help me out using the simplest English words. public class BalancedStrings { public static void printBalanced(String prefix, int a, int b) { if (a > 0) printBalanced(prefix + "a", a - 1, b); if (b > 0) printBalanced(prefix + "b", a, b - 1); if (a == 0 && b == 0) System.out.println(prefix); } public static void printBalanced(int n) { if (n % 2 == 0) { printBalanced("", n / 2, n / 2); } } public static void main(String[] args) { printBalanced(4); } }

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  • Subquery max sequence number

    - by Andy Levesque
    I'm hesitant to ask because I'm sure it's out there, but I just can't seem to come up with the keywords to find the answer. I'm stepping outside my boundaries by starting with subqueries (normally an Access user). I have a query that has TECH_ID, SEQ_NBR, and PELL_FT_AWD_AMT SELECT ISRS_V_NEED_ANAL_RESULT_PARENT.TECH_ID, ISRS_V_NEED_ANAL_RESULT_PARENT.AWD_YR, ISRS_V_NEED_ANAL_RESULT_PARENT.PELL_FT_AWD_AMT, ISRS_V_NEED_ANAL_RESULT_PARENT.SEQ_NBR FROM ISRS_V_NEED_ANAL_RESULT_PARENT GROUP BY ISRS_V_NEED_ANAL_RESULT_PARENT.TECH_ID, ISRS_V_NEED_ANAL_RESULT_PARENT.AWD_YR, ISRS_V_NEED_ANAL_RESULT_PARENT.PELL_FT_AWD_AMT, ISRS_V_NEED_ANAL_RESULT_PARENT.SEQ_NBR HAVING (((ISRS_V_NEED_ANAL_RESULT_PARENT.AWD_YR)="2013")) ORDER BY ISRS_V_NEED_ANAL_RESULT_PARENT.TECH_ID; What I want to return is add a subquery that selects only the max SEQ_NUM for each record, but I can't seem to get the syntax right. In the past I would cheat and have a separate query that first gave me the TECH_ID and max SEQ_NUM, and then have a second query that use the original table and the first query in a join to get the rest. How can I do this in one query? Example: TECH_ID SEQ_NUM PELL 1 1 4000 1 2 4000 1 3 5000 Using just the max of the sequence number still returns: 1; 2; 4000 and 1; 3; 5000 when I'm only wanting the latter.

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  • A typical mysql query( how to use subquery column into main query)

    - by I Like PHP
    I HAVE TWO TABLES shown below table_joining id join_id(PK) transfer_id(FK) unit_id transfer_date joining_date 1 j_1 t_1 u_1 2010-06-05 2010-03-05 2 j_2 t_2 u_3 2010-05-10 2010-03-10 3 j_3 t_3 u_6 2010-04-10 2010-01-01 4 j_5 NULL u_3 NULL 2010-06-05 5 j_6 NULL u_4 NULL 2010-05-05 table_transfer id transfer_id(PK) pastUnitId futureUnitId effective_transfer_date 1 t_1 u_3 u_1 2010-06-05 2 t_2 u_6 u_1 2010-05-10 3 t_3 u_5 u_3 2010-04-10 now i want to know total employee detalis( using join_id) which are currently working on unit u_3 . means i want only join_id j_1 (has transfered but effective_transfer_date is future date, right now in u_3) j_2 ( tansfered and right now in `u_3` bcoz effective_transfer_date has been passed) j_6 ( right now in `u_3` and never transfered) what i need to take care of below steps( as far as i know ) <1> first need to check from table_joining whether transfer_id is NULL or not <2> if transfer_id= is NULL then see unit_id=u_3 where joining_date <=CURDATE() ( means that person already joined u_3) <3> if transfer_id is NOT NULL then go to table_transfer using transfer_id (foreign key reference) <4> now see the effective_transfer_date regrading that transfer_id whether effective_transfer_date<=CURDATE() <5> if transfer date has been passed(means transfer has been done) then return futureUnitID otherwise return pastUnitID i used two separate query but don't know how to join those query?? for step <1 ans <2 SELECT unit_id FROM table_joining WHERE joining_date<=CURDATE() AND transfer_id IS NULL AND unit_id='u_3' for step<5 SELECT IF(effective_transfer_date <= CURDATE(),futureUnitId,pastUnitId) AS currentUnitID FROM table_transfer // here how do we select only those rows which have currentUnitID='u_3' ?? please guide me the process?? i m just confused with JOINS. i think using LEFT JOIN can return the data i need, or if we use subquery value to main query? but i m not getting how to implement ...please help me. Thanks for helping me alwayz

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  • MySQL subquery and bracketing

    - by text
    Here are my tables respondents: field sample value respondentid : 1 age : 2 gender : male survey_questions: id : 1 question : Q1 answer : sample answer answers: respondentid : 1 question : Q1 answer : 1 --id of survey question I want to display all respondents who answered the certain survey, display all answers and total all the answer and group them according to the age bracket. I tried using this query: SELECT res.Age, res.Gender, answer.id, answer.respondentid, SUM(CASE WHEN res.Gender='Male' THEN 1 else 0 END) AS males, SUM(CASE WHEN res.Gender='Female' THEN 1 else 0 END) AS females, CASE WHEN res.Age < 1 THEN 'age1' WHEN res.Age BETWEEN 1 AND 4 THEN 'age2' WHEN res.Age BETWEEN 4 AND 9 THEN 'age3' WHEN res.Age BETWEEN 10 AND 14 THEN 'age4' WHEN res.Age BETWEEN 15 AND 19 THEN 'age5' WHEN res.Age BETWEEN 20 AND 29 THEN 'age6' WHEN res.Age BETWEEN 30 AND 39 THEN 'age7' WHEN res.Age BETWEEN 40 AND 49 THEN 'age8' ELSE 'age9' END AS ageband FROM Respondents AS res INNER JOIN Answers as answer ON answer.respondentid=res.respondentid INNER JOIN Questions as question ON answer.Answer=question.id WHERE answer.Question='Q1' GROUP BY ageband ORDER BY res.Age ASC I was able to get the data but the listing of all answers are not present. Do I have to subquery SELECT into my current SELECT statement to show the answers? I want to produce something like this: ex: # of Respondents is 3 ages: 2,3 and 6 Question: what are your favorite subjects? Ages 1-4: subject 1: 1 subject 2: 2 subject 3: 2 total respondents for ages 1-4 : 2 Ages 5-10: subject 1: 1 subject 2: 1 subject 3: 0 total respondents for ages 5-10 : 1

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  • How significant is the bazaar performance factor?

    - by memodda
    I hear all this stuff about bazaar being slower than git. I haven't used too much distributed version control yet, but in Bazaar vs. Git on the bazaar site, they say that most complaints about performance aren't true anymore. Have you found this to be true? Is performance pretty much on par now? I've heard that speed can affect workflow (people are more likely to do good thing X if X is fast). What specific cases does performance currently affect workflow in bazaar vs other systems (especially git), and how? I'm just trying to get at why performance is of particular importance. Usually when I check something in or update it, I expect it to take a little while, but it doesn't matter. I commit/update when I have a second, so it doesn't interfere with my productivity. But then I haven't used DVCS yet, so maybe that has something to do with it?

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  • Is there a way to split/factor out common parts of Gradle build

    - by Superfilin
    We have several independent builds (each independent build is a multi-project build). The main build scripts become quite big as we have a set of common tasks reused by subprojects as well as there is a lot of repeation between indepedent builds. What we are looking for is: A way to split main build file into smaller files A way to reuse some parts of the build in other independent builds What is the best way to achieve that in Gradle?

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  • Websphere 7 and JSF 1.2 - Application was not properly initialized at startup, could not find Factor

    - by Shamik
    JSF 1.1 and websphere 6.1 was working properly in my case. Once I deployed that to a websphere 7 server, I received the following error - Application was not properly initialized at startup, could not find Factory: javax.faces.context.FacesContextFactoryat javax.faces.FactoryFinder.getFactory(FactoryFinder.java:270) at javax.faces.webapp.FacesServlet.init(FacesServlet.java:164) at com.ibm.ws.webcontainer.servlet.ServletWrapper.init(ServletWrapper.java:358) at com.ibm.ws.webcontainer.servlet.ServletWrapperImpl.init(ServletWrapperImpl.java:168) Not sure what it means, I have enabled JSF1.2 as project facet in the RAD but still keep getting the above error message and none of my jsf files are working.

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