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  • why is there extra using where in execution plan of query

    - by user366534
    I see plan of query: EXPLAIN SELECT * FROM `subscribers` WHERE state =4 AND date_added < '2010-12-23 11:47:45' It shows: id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE subscribers range state_date_added state_date_added 9 NULL 8 Using where Here is indexes of table: Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment subscribers 0 PRIMARY 1 subscriber_id A 382039 NULL NULL BTREE subscribers 0 email_list_id 1 email_address A 191019 NULL NULL BTREE subscribers 0 email_list_id 2 list_id A 382039 NULL NULL BTREE subscribers 1 FK_list_id 1 list_id A 10 NULL NULL BTREE subscribers 1 state_date_added 1 state A 12 NULL NULL BTREE subscribers 1 state_date_added 2 date_added A 8128 NULL NULL BTREE The last two lines describes index what is supposed for the query. Why is there in extra column using where? Even If I fetch only state and date_added column, it has in extra column: Using where; Using index. I understand why it has using index, but I don't understand Using where here.

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  • A B+tree simple implementation in C

    - by initpy
    Hi guys, I'm working on a fun project where I need a simple key/value store that uses B+Trees. I studied them some years ago, and to be honest, I don't want to reinvent the wheel, so I'm looking for a simple implementation in C of b+tree that I can just include in my project. I know of sqlite's, dbm's and tokyocabinet's ones but they're a little too "complicated" for my needs. Is there any (even pedagogical) work on this you can refer me to? Do you have some code to share? Thanks a lot!

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  • Excel Spreadsheet - Best way to perform an Oracle Query on a cell

    - by Jamie
    Hi there, I have an Excel Spreadsheeet. There is a cell containing a concatenated name and surname (don't ask why), for example: Cell A2 BLOGGSJOE On this cell, I would like to run the following SQL and output it to cell A3, A4 and A5 SELECT i.id, i.forename, i.surname FROM individual i WHERE UPPER(REPLACE('" & A2 & "', ' ', '')) = UPPER(REPLACE(i.surname|| i.forename, ' ', '')) AND NVL(i.ind_efface, 'N') = 'N' Any idea how I could perform an oracle query on each cell and return the result? I have enabled an oracle datasource connection in Excel, just not sure what to do now. Is this a stupid approach, and can you recommend a better more proficient way? Thanks muchly! I lack the necessary experience in this type of thing! :-) EDIT: I am aware that I could just write a simple ruby/php/python/whatever script to loop through the excel spreadsheet (or csv file), and then perform the query etc. but i thought there might be a quick way in excel itself.

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  • What data is actually stored in a B-tree database in CouchDB?

    - by Andrey Vlasovskikh
    I'm wondering what is actually stored in a CouchDB database B-tree? The CouchDB: The Definitive Guide tells that a database B-tree is used for append-only operations and that a database is stored in a single B-tree (besides per-view B-trees). So I guess the data items that are appended to the database file are revisions of documents, not the whole documents: +---------|### ... | | +------|###|------+ ... ---+ | | | | +------+ +------+ +------+ +------+ | doc1 | | doc2 | | doc1 | ... | doc1 | | rev1 | | rev1 | | rev2 | | rev7 | +------+ +------+ +------+ +------+ Is it true? If it is true, then how the current revision of a document is determined based on such a B-tree? Doesn't it mean, that CouchDB needs a separate "view" database for indexing current revisions of documents to preserve O(log n) access? Wouldn't it lead to race conditions while building such an index? (as far as I know, CouchDB uses no write locks).

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  • ResultSet and aggregation

    - by kachanov
    Ok, I admit my situation is special There is a data system that supports SQL-92 and JDBC interface However the SQL requets are pretty expensive, and in my application I need to retreive the same data multiple times and aggregate it ("group by") on different fields to show different dimensions of the same data. For example on one screen I have three tables that show the same set or records but aggregated by City (1st grid), by Population (2nd grid), by number of babies (3rd grid) This amounts to 3 SQL queries (which is very slow), UNLESS anyone of you can suggest any idea any library from apache commons or from google code, so that I can select all records into ResultSet and get 3 arrays of data group by different fields from this single ResultSet. Am I'm missing some obvious and unexpected solution to this problem?

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  • How to handle customers with multiple addresses in CakePHP

    - by Ryan
    I'm putting together a system to track customer orders. Each order will have three addresses; a Main contact address, a billing address and a shipping address. I do not want to have columns in my orders table for the three addresses, I'd like to reference them from a separate table and have some way to enumerate the entry so I can determine if the addressing is main, shipping or billing. Does it make sense to create a column in the address table for AddressType and enumerate that or create another table - AddressTypes - that defines the address enumeration and link to that table? I have found other questions that touch on this topic and that is where I've taken my model. The problem I'm having is taking that into the cakePHP convention. I've been struggling to internalize the direction OneToMany relationships are formed - the way the documentation states feels backwards to me. Any help would be appreciated, Thanks!

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  • Oracle (Old?) Joins - A tool/script for conversion?

    - by Grasper
    I have been porting oracle selects, and I have been running across a lot of queries like so: SELECT e.last_name, d.department_name FROM employees e, departments d WHERE e.department_id(+) = d.department_id; ...and: SELECT last_name, d.department_id FROM employees e, departments d WHERE e.department_id = d.department_id(+); Are there any guides/tutorials for converting all of the variants of the (+) syntax? What is that syntax even called (so I can scour google)? Even better.. Is there a tool/script that will do this conversion for me (Preferred Free)? An optimizer of some sort? I have around 500 of these queries to port.. When was this standard phased out? Any info is appreciated.

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  • Back out plan for a Web App

    - by nobody
    We need a back out plan for a web app whose first maintenance release is going to production soon. The issue we are facing is even if we back out new EAR and deploy old one , the data which was keyed in using new release would not support old business rules(current), since there is enormous changes in business rules. Can you suggest how do we tackle this issue?

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  • Creating a Web Service to automatically get information

    - by Sean P
    I want to create some sort of method of creating a web service that will run automatically and run DB queries and some API calls which will then store data that I can use/call without taking the processing or time penalty of doing it every time a user access my web service. Is this possible? If so, point me in the right direction on how to implement something like this Using vb.net and ASP.net Thanks in advance!!

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  • Mysql random rows

    - by n00b
    please read the whole question... 90% of you dont seem to do that and some of you only read the title obviously... and if you dont know the solution, dont answer - i wont have to downvote you -.-'' im entertaining the idea of getting random rows directly from mysql. what i found was SELECT * FROM tablename WHERE somefield='something' ORDER BY RAND() LIMIT 5 but even i see how slow that would be.. is the only way to do this doing something like SELECT * FROM tablename WHERE somefield='something' LIMIT RAND(aincrementvalue-5), 1 5 times? or is there a way that i with my little knowlege of databases cant come up with ? (no i dont want random indexes. i hate the idea of them...) @commenters - please first look, then think, then look again, think again and then post. i wont point fingers but i dislike stupid comments and why i think random indexes are a nasty hack ? it doesnt give you random results. it gives you x results from a random index in a predefined order its like a gapless id only in the wrong order if you fetch by 1 row and get true randomness you fall back to my method but with an additional junk field finally the reason the field exists is only to serve as a helper to something that can be done without it with almost same performance (but the quality (randomness) is better), so it is a nasty hack ;) i solved it, look @ my answer... if you think its incorrect please tell me :)

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  • MS Access CrossTab query - across 3 tables

    - by Prembo
    Hi, I have the following 3 tables: 1) Sweetness Table FruitIndex CountryIndex Sweetness 1 1 10 1 2 20 1 3 400 2 1 50 2 2 123 2 3 1 3 1 49 3 2 40 3 3 2 2) Fruit Name Table FruitIndex FruitName 1 Apple 2 Orange 3 Peaches 3) Country Name Table CountryIndex CountryName 1 UnitedStates 2 Canada 3 Mexico I'm trying to perform a CrossTab SQL query to end up with: Fruit\Country UnitedStates Canada Mexico Apple 10 20 400 Orange 50 123 1 Peaches 49 40 2 The challenging part is to label the rows/columns with the relevant names from the Name tables. I can use MS Access to design 2 queries, create the joins the fruit/country names table with the Sweetness table perform crosstab query However I'm having trouble doing this in a single query. I've attempted nesting the 1st query's SQL into the 2nd, but it doesn't seem to work. Unfortunately, my solution needs to be be wholly SQL, as it is an embedded SQL query (cannot rely on query designer in MS Access, etc.). Any help greatly appreciated. Prembo.

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  • Normalise this Table?

    - by Abs
    Hello all, I am creating a social bookmarking app. I am having a re-thought of the DB design in the middle of development. Should I normalise the bookmarks table and remove the tag columns that I have into a separate table. I have 10 tags per bookmark and therefore 10 columns per record (per bookmark). It seems to me that breaking the table into two would just mean I would have to do a join but the way I currently have it, its a straight select - but the table doesn't feel right...? Thanks all

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  • When to use SQL Table Alias

    - by Rossini
    I curious to know how people are using table alias. The other developers where I work always use table alias, and always use the alias of a, b, c, ect. Here's an example SELECT a.TripNum, b.SegmentNum, b.StopNum, b.ArrivalTime FROM Trip a, Segment b WHERE a.TripNum = b.TripNum I disagree with them, and think table alias should be use more sparingly. I think it should be used when including the same table twice in a query, or when the table name is very long and using a shorter name in the query will make the query easier to read. I also think the alias should be a good name instead of a letter. In the above example if I felt I needed to use 1 letter table alias I would use t for the Trip table and s for the segment table.

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  • large databases in sqlite - file size considerations?

    - by Gj
    I'm using a sqlite db which is very convenient and seems to meet all of my needs at this point. Currently my db size is <50MB, but I now need to add a new table which will store large text blobs, which will cause the db to reach up to 5GB within the next year. Would sqlite be able to deal with a 5GB db size? Any caveats to that, compared with say mysql?

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  • question with its query

    - by user329820
    Hi this is my homework and the question is this: List the average balance of customers by city and short zip code (the first five digits of thezip code). Only include customers residing in Washington State (‘WA’). also the Customer table has 5 columns(Name,Family,CustZip,CustCity,CustAVGBal) I wrote the query like below is this correct? SELECT CustCity,LEFT(CustZip,5) AS NewCustZip,CustAVGBal FROM Customer WHERE CustCity = 'WA' THANKS!!

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  • Search Oracle date type column with hibernate, seach by everything in that day - ignore the time.

    - by Setori
    hi there <property name="batchCreatedDate" type="java.util.Date"> <meta attribute="field-description">batch create date</meta> <column name="BATCH_CREATED_DATE" length="7" not-null="true" /> </property> table column type is BATCH_CREATED_DATE DATE NOT NULL With the data in that date column being similar to this '2010-05-13 14:56:36.0' now I want to search for all items within the 24 hours of 2010-05-13, currently my call only returns all items with date "2010-05-13 14:56:36.0" exactly. What would my HQL statement look like to hand this kind of scenario? Thank you so much

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  • Oracle join query

    - by Jasim
    There are three tables in my db ITEM_MASTER, PRICE_MASTER, COMP_MASTER ITEM_MASTER STORE_CODE ITEM_CODE ITEM_DESC 011 914004 desccc PRICE_MASTER STORE_CODE ITEM_CODE COMP_CODE 011 914004 01 011 914004 02 011 914004 03 011 914004 04 COMP_MASTER COMP_CODE COMP_DESC STORE_CODE 01 comp1 011 02 comp2 011 03 comp3 011 04 comp4 011 I want to get all these for an ITEM_CODE in single query STORE_CODE ITEM_CODE ITEM_DESC COMP_DESC1 COMP_DESC2 COMP_DESC3 COMP_DESC4 011 914004 desccc comp1 comp2 comp3 comp4 How can i write a oracle SQL query for this??

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  • Do you know of a good F# and C# interop example available?

    - by Ivan
    I am going to write a C# WinForms application which will run a long data-crunching task in a BackgroundWorker, show progress in a ProgressBar and have buttons to start, pause, resume and cancel the operation. I'd like to write the calculation in F#. Do you know of any good examples or readings available in the Web which can help me?

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  • Get current updated column name to use in a trigger

    - by Serge
    Is there a way to actually get the column name that was updated in order to use it in a trigger? Basically I'm trying to have an audit trail whenever a user inserts or updates a table (in this case it has to do with a Contact table) CREATE TRIGGER `after_update_contact` AFTER UPDATE ON `contact` FOR EACH ROW BEGIN INSERT INTO user_audit (id_user, even_date, table_name, record_id, field_name, old_value, new_value) VALUES (NEW.updatedby, NEW.lastUpdate, 'contact', NEW.id_contact, [...]) END How can I get the name of the column that's been updated and from that get the OLD and NEW values of that column. If multiple columns have been updated in a row or even multiple rows would it be possible to have an audit for each update?

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