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  • Generic Method to find the tuples used for computation in Postgres?

    - by Rahul
    If I have a table col1 | name | pay ------+------------------+------ 1 | Steve Jobs | 1006 2 | Mike Markkula | 1007 3 | Mike Scott | 1978 4 | John Sculley | 1983 5 | Michael Spindler | 1653 The user executes a sum query which sums the pay of people getting paid more than $1500. Is there a way to also implicitly know which tuples have been used which satisfy the condition for sum ? I know you can separately write another query to just return the primary key ids which satisfy the condition. But, Is there any other way to do that in the same query ? probably rewrite the query in some way ? or... any suggestion ?

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  • archiving strategies and limitations of data in a table

    - by Samuel
    Environment: Jboss, Mysql, JPA, Hibernate Our web application will be catering to a large amount of users (~ 1,000,000) and there are a lots of child table where user specific data are stored (e.g. personal, health, forum contributions ...). What would be the best practice to archive user & user specific information. [a] Would it be wise to move the archived user & user specific information to their respective tables within the same database (e.g. user_archive, user_forum_comments_archive ...) OR [b] Would you just mark the database entries with a flag in the original table(s) and just query only non archived entries. We have a unique constraint on User.loginid, how do you handle this requirement if the users are archived via 1-[a] (i.e if a user with loginid 'samuel' gets moved into the archive table and if a new user gets added with the same name in the original table, how would you prevent this. What would be the best strategy to address the unique key constraints. We have a requirement to selectively archive records and bring it back if necessary, will you rely on database tools are would you handle this via your persistence APIs exposed by the JPA entity model.

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  • Can't return a List from a Compiled Query.

    - by Andrew
    I was speeding up my app by using compiled queries for queries which were getting hit over and over. I tried to implement it like this: Function Select(ByVal fk_id As Integer) As List(SomeEntity) Using db As New DataContext() db.ObjectTrackingEnabled = False Return CompiledSelect(db, fk_id) End Using End Function Shared CompiledSelect As Func(Of DataContext, Integer, List(Of SomeEntity)) = _ CompiledQuery.Compile(Function(db As DataContext, fk_id As Integer) _ (From u In db.SomeEntities _ Where u.SomeLinkedEntity.ID = fk_id _ Select u).ToList()) This did not work and I got this error message: Type : System.ArgumentNullException, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089 Message : Value cannot be null. Parameter name: value However, when I changed my compiled query to return IQueryable instead of List like so: Function Select(ByVal fk_id As Integer) As List(SomeEntity) Using db As New DataContext() db.ObjectTrackingEnabled = False Return CompiledSelect(db, fk_id).ToList() End Using End Function Shared CompiledSelect As Func(Of DataContext, Integer, IQueryable(Of SomeEntity)) = _ CompiledQuery.Compile(Function(db As DataContext, fk_id As Integer) _ From u In db.SomeEntities _ Where u.SomeLinkedEntity.ID = fk_id _ Select u) It worked fine. Can anyone shed any light as to why this is? BTW, compiled queries rock! They sped up my app by a factor of 2.

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  • mysql query for getting all messages that belong to user's contacts

    - by aharon
    So I have a database that is setup sort of like this (simplified, and in terms of the tables, all are InnoDBs): Users: contains based user authentication information (uid, username, encrypted password, et cetera) Contacts: contains two rows per relationship that exists between users as (uid1, uid2), (uid2, uid1) to allow for a good 1:1 relationship (must be mutual) between users Messages: has messages that consist of a blob, owner-id, message-id (auto_increment) So my question is, what's the best MySQL query to get all messages that belong to all the contacts of a specific user? Is there an efficient way to do this?

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  • Search 2 Columns with 1 Input Field

    - by Norbert
    I have a db with two columns: first name and last name. The first name can have multiple words. Last name can contain hyphenated words. Is there a way to search both columns with only one input box? Database ID `First Name` `Last Name` 1 John Peter Doe 2 John Fubar 3 Michael Doe Search john peter returns id 1 john returns id 1,2 doe returns id 1,3 john doe returns id 1 peter john returns id 1 peter doe returns id 1 doe john returns id 1 I previously tried the following. Searching for John Doe: SELECT * FROM names WHERE ( `first` LIKE '%john%' OR `first` LIKE '%doe%' OR `last` LIKE '%john%' OR `last` LIKE '%doe%' ) which returns both 1 and 3

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  • Facebook database design?

    - by Marin
    I have always wondered how Facebook designed the friend <- user relation. I figure the user table is something like this: user_email PK user_id PK password I figure the table with user's data (sex, age etc connected via user email I would assume). How does it connect all the friends to this user? Something like this? user_id friend_id_1 friend_id_2 friend_id_3 friend_id_N Probably not. Because the number of users is unknown and will expand.

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  • How do these user/userParam references relate to the Customer and Account lookups?

    - by plath
    In the following code example how do the user/userParam references relate to the Customer and Account lookups and what is the relationship between Customer and Account? // PersistenceManager pm = ...; Transaction tx = pm.currentTransaction(); User user = userService.currentUser(); List<Account> accounts = new ArrayList<Account>(); try { tx.begin(); Query query = pm.newQuery("select from Customer " + "where user == userParam " + "parameters User userParam"); List<Customer> customers = (List<Customer>) query.execute(user); query = pm.newQuery("select from Account " + "where parent-pk == keyParam " + "parameters Key keyParam"); for (Customer customer : customers) { accounts.addAll((List<Account>) query.execute(customer.key)); } } finally { if (tx.isActive()) { tx.rollback(); } }

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  • postgresql: Fast way to update the latest inserted row

    - by Anonymous
    What is the best way to modify the latest added row without using a temporary table. E.g. the table structure is id | text | date My current approach would be an insert with the postgresql specific command "returning id" so that I can update the table afterwards with update myTable set date='2013-11-11' where id = lastRow However I have the feeling that postgresql is not simply using the last row but is iterating through millions of entries until "id = lastRow" is found. How can i directly access the last added row?

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  • What resources will help me understand the fundamentals of Relational Database Systems.

    - by Rachel
    This are few of the fundamental database questions which has always given me trouble. I have tried using google and wiki but I somehow I miss out on understanding the functionality rather than terminology. If possible would really appreciate if someone can share more insights on this questions using some visual representative examples. What is a key? A candidate key? A primary key? An alternate key? A foreign key? What is an index and how does it help your database? What are the data types available and when to use which ones?

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  • SqlCommand asp.net C#

    - by emilios
    i you please help me out with my problem i am trying to create a function that output the data on a dropdownlist an setting my parameters my code goes as follow : public static List<string> GetTracks(out List<string> trackIds, string conferenceId) { var res = new List<string>(); trackIds = new List<string>(); var sqlCon = new SqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString); SqlCommand cmd = new SqlCommand("select Track_name,Track_ID from TrackCommittee where Conference_id= @conferenceId", sqlCon); DataSet ds = new DataSet(); cmd.Connection.Open(); cmd.Parameters.Add(new SqlParameter("@conferenceId", conferenceId)); using (SqlDataReader sdr = cmd.ExecuteReader()) { while (sdr.Read()) { res.Add(sdr.GetString(sdr.GetOrdinal("Track_name"))); trackIds.Add(sdr.GetInt32(sdr.GetOrdinal("Track_ID")).ToString()); } } cmd.Connection.Close(); cmd.Dispose(); return res; } thanking you in advance

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  • Understand Sql Server connectionstring for asp.net

    - by Eatdoku
    Hi, I am trying to understand the differences between the following 2 connectionstrings. one uses servername\instancename and the other one uses the server ip address. Can I specify port number for "serverName\instanceName". I know you can specify port number for ip address, something like '10.0.0.1,xxx'. thanks, Server=myServerName\theInstanceName;Database=myDataBase;Trusted_Connection=True; Server=myServerAddress;Database=myDataBase;Trusted_Connection=True;

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  • Round date to fiscal year

    - by Dave Jarvis
    The following database view rounds the date back to the closest fiscal year (April 1st): CREATE OR REPLACE VIEW FISCAL_YEAR_VW AS SELECT CASE WHEN to_number(to_char( SYSDATE, 'MM' )) < 4 THEN to_date('1-APR-'||to_char(add_months(SYSDATE, -12), 'YYYY'), 'dd-MON-yyyy') ELSE to_date('1-APR-'||to_char(SYSDATE, 'YYYY'), 'dd-MON-yyyy') END AS fiscal_year FROM dual; This allows us to calculate the current fiscal year based on today's date. How can this calculation be simplified or optimized?

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  • To log in stored procedures?

    - by hgulyan
    If you have a long running SP, do you log somehow it's actions or just wait for this message? "Command(s) completed successfully." I assume, that there can be plenty solutions on this subject, but is there any best practice - a simple solution that is frequently used?

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  • Query a range of date

    - by juniorSE
    Hello Guys, Im trying to query a sort of from - to date. e.g. 20-01-2010 to 20-02-2010. this should include the mentioned dates. i've tried the following queries but none works. select * from [tableName] where date = '20-01-2010' AND date <= '20-02-2010' the date where date is equal to 20-02-2010 does not show. i don't know why. select * from [tableName] where date between '20-01-2010' AND '20-02-2010' the mentioned dates is not included in the results. i want it to be included in the results. please help. thanks in advance! :)

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  • ibatis/Oracle - SELECT query inside INSERT is failing

    - by whoopy_whale
    Hi, I'm trying to do an Insert operation using iBatis. INSERT INTO SCHEMA.TABLE (FIELD1, FIELD2, FIELD3) VALUES (#field1#, (SELECT ANOTHER_FIELD FROM SCHEMA.TABLE WHERE FIELD4= #field2#), #field2#) The inner select query always fails and returns NULL. But if I substitute #field2# with the actual value only in the inner query, it works fine. Why is iBatis not substituting fieldvalues in the innerqueries? Any ideas?

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  • Why does this query only select a single row?

    - by Joe
    SELECT * FROM tbl_houses WHERE (SELECT HousesList FROM tbl_lists WHERE tbl_lists.ID = '123') LIKE CONCAT('% ', tbl_houses.ID, '#') It only selects the row from tbl_houses of the last occuring tbl_houses.ID inside tbl_lists.HousesList I need it to select all the rows where any ID from tbl_houses exists within tbl_lists.HousesList

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  • Insert Data from to a table

    - by Lee_McIntosh
    I have a table that lists number of comments from a particular site like the following: Date Site Comments Total --------------------------------------------------------------- 2010-04-01 00:00:00.000 1 5 5 2010-04-01 00:00:00.000 2 8 13 2010-04-01 00:00:00.000 4 2 7 2010-04-01 00:00:00.000 7 13 13 2010-04-01 00:00:00.000 9 1 2 I have another table that lists ALL sites for example from 1 to 10 Site ----- 1 2 ... 9 10 Using the following code i can find out which sites are missing entries for the previous month: SELECT s.site from tbl_Sites s EXCEPT SELECT c.site from tbl_Comments c WHERE c.[Date] = DATEADD(mm, DATEDIFF(mm, 0, GetDate()) -1,0) Producing: site ----- 3 5 6 8 10 I would like to be able to insert the missing sites that is listed from my query into the comments table with some default values, i.e '0's Date Site Comments Total --------------------------------------------------------------- 2010-04-01 00:00:00.000 3 0 0 2010-04-01 00:00:00.000 5 0 0 2010-04-01 00:00:00.000 6 0 0 2010-04-01 00:00:00.000 8 0 0 2010-04-01 00:00:00.000 10 0 0 the question is, how did i update/insert the table/values? cheers, Lee

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  • Struggling to create correct relationships in MS Access

    - by Yandawl
    http://img714.imageshack.us/img714/7820/croppercapture1.png Basically: an award(course) has many units, which can be either optional or core(mandatory), depending on the award. So for example: the unit 'Advanced Software Engineering' maybe a core unit for the award 'Software Engineering BSc' but only an optional unit for the course 'Web Technology BSc'. I've used flags for that purpose. A student is enrolled on an award so I need to get a complete list of core and optional units (bearing in mind that a student chooses 1 out of many possible optional units). Also, these units have events, e.g, a lecture, workshop or seminar, etc. and those events have sessions or instances of events where students enrolled on that particular unit are required to attend, and those attendances are stored in a separate table to form a register. So I need a hierarchy of expanding the tables something like this I guess: Awards - Students - Units - Sessions - Attendances Any help with this would be appreciated... It's blowing my mind and I'm really close to going insane! My tutor didn't spot I'd got it wrong when I showed my original data model to him and it's due in next week! Thank you :D

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  • SQL2008 merge replication fails to update depdendent items when table is added

    - by Dan Puzey
    Setup: an existing SQL2008 merge replication scenario. A large server database, including views and stored procs, being replicated to client machines. What I'm doing: * adding a new table to the database * mark the new table for replication (using SP_AddMergeArticle) * alter a view (which is already part of the replicated content) is updated to include fields from this new table (which is joined to the tables in the existing view). A stored procedure is similarly updated. The problem: the table gets replicated to client machines, but the view is not updated. The stored procedure is also not updated. Non-useful workaround: if I run the snapshot agent after calling SP_AddMergeArticle and before updating the view/SP, both the view and the stored procedure changes correctly replicate to the client. The bigger problem: I'm running a list of database scripts in a transaction, as part of a larger process. The snapshot agent can't be run during a transaction, and if I interrupt the transaction (e.g. by running the scripts in multiple transactions), I lose the ability to roll back the changes should something fail. Does anyone have any suggestions? It seems like I must be missing something obvious, because I don't see why the changes to the view/sproc wouldn't be replicating anyway, regardless of what's going on with the new table.

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  • SQLite long to wide formats?

    - by Stephen
    Hi, I wonder if there is a canonical way to convert data from long to wide format in SQLite (is that operation usually in the domain of relational databases?). I tried to follow this example for MySQL but I guess SQLite does not have the same IF construct... Thanks!

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  • MySQL - Finding time overlaps

    - by Jude
    Hi, I have 2 tables in the database with the following attributes: Booking ======= booking_id booking_start booking_end resource_booked =============== booking_id resource_id The second table is an associative entity between "Booking" and "Resource" (i.e., 1 booking can contain many resources). Attributes booking_start and booking_end are timestamps with date and time in it. May I know how I might be able to find out for each resource_id (resource_booked) if the date/time overlaps or clashes with other bookings of similar resource_id? I was doodling the answer on paper, pictorially, to see if it might help me visualize how I could solve this and I got this: Joining the 2 tables (Booking, Booked_resource) into one table with the 4 attributes needed. Follow the answer suggested here : http://stackoverflow.com/questions/689458/find-overlapping-date-time-rows-within-one-table I did step 1 but step 2 is leaving me baffled! I would really appreciate any help on this! Thanks!

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  • What are the disadvantages of VistaDB

    - by PhantomTypist
    I am looking into using a lightweight serverless database engine like SQLite, Firebird, or VistaDB in an upcoming project. Someone asked about What are the advantages of VistaDB. I would like to know what are the disadvantages of using VistaDB versus other technology?

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