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  • How to create a better tables Structure.

    - by user160820
    For my website i have tables Category :: id | name Product :: id | name | categoryid Now each category may have different sizes, for that I have also created a table Size :: id | name | categoryid | price Now the problem is that each category has also different ingredients that customer can choose to add to his purchased product. And these ingredients have different prices for different sizes. For that I also have a table like Ingredient :: id | name | sizeid | categoryid | price I am not sure if this Structure really normalized is. Can someone please help me to optimize this structure and which indexed do i need for this Structure?

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  • MySQL: Limit output according to associated ID

    - by Jess
    So here's my situation. I have a books table and authors table. An author can have many books... In my authors page view, the user (logged in) can click an author in a tabled row and be directed to a page displaying the author's books (collected like this URI format: viewauthorbooks.php?author_id=23), very straight forward... However, in my query, I need to display the books for the author only, and not all books stored in the books table (as i currently have!) As I am a complete novice, I used the most simple query of: SELECT * FROM tasks_tb This returns the books for me, but returns every single value (book) in the database, and not ones associated with the selected author. And when I click a different author the same books are displayed for them...I think everyone gets what I'm trying to achieve, I just don't know how to perform the query. I'm guessing that I need to start using more advanced query clauses like INNER JOIN etc. Anyone care to help me out :)

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  • add array element to row returned from sql query

    - by bert
    I want to add an additional value into an array before passing it to json_encode function, but I can't get the syntax right. $result = db_query($query); // $row is a database query result resource while ($row = db_fetch_object($result)) { $stack[] = $row; // I am trying to 'inject' array element here $stack[]['x'] = "test"; } echo json_encode($stack);

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  • How would I implement separate databases for reading and writing operations?

    - by Matt
    I am interested in implementing an architecture that has two databases one for read operations and the other for writes. I have never implemented something like this and have always built single database, highly normalised systems so I am not quite sure where to begin. I have a few parts to this question. 1. What would be a good resource to find out more about this achitecture? 2. Is it just a question of replicating between two identical schemas, or would your schemas differ depending on the operations, would normalisation vary too? 3. How do you insure that data written to one database is immediately available for reading from the second? Any further help, tips, resources would be appreciated. Thanks.

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  • Strange behavior with large Object Types

    - by Peter Lang
    I recognized that calling a method on an Oracle Object Type takes longer when the instance gets bigger. The code below just adds rows to a collection stored in the Object Type and calls the empty dummy-procedure in the loop. Calls are taking longer when more rows are in the collection. When I just remove the call to dummy, performance is much better (the collection still contains the same number of records): Calling dummy: Not calling dummy: 11 0 81 0 158 0 Code to reproduce: Create Type t_tab Is Table Of VARCHAR2(10000); Create Type test_type As Object( tab t_tab, Member Procedure dummy ); Create Type Body test_type As Member Procedure dummy As Begin Null; --# Do nothing End dummy; End; Declare v_test_type test_type := New test_type( New t_tab() ); Procedure run_test As start_time NUMBER := dbms_utility.get_time; Begin For i In 1 .. 200 Loop v_test_Type.tab.Extend; v_test_Type.tab(v_test_Type.tab.Last) := Lpad(' ', 10000); v_test_Type.dummy(); --# Removed this line in second test End Loop; dbms_output.put_line( dbms_utility.get_time - start_time ); End run_test; Begin run_test; run_test; run_test; End; I tried with both 10g and 11g. Can anyone explain/reproduce this behavior?

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  • How to merge existing row with new data in SQLite?

    - by CSharperWithJava
    I have a database full of simple note data, with columns for title, due date, priority, and details. There is also a _id column PRIMARY KEY int. Say I have a note in the table already with some data filled and the rest null. I also have a set of data that will fill all those fields. Is there a way that I can only write data to the fields that are NULL? I can't overwrite existing data, but I'd like to add data to NULL columns. I know the rowId of the target row. If my target row had rowId of 5, I could do something like this: UPDATE SET duedate='some date', priority='2', details='some text' WHERE _id=5 But that would overwrite all the data in that row, and I don't want to lose any data that might be there. How can I change this statement to avoid writing to non-null fields?

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  • How can i learn Table Name in database an column name?

    - by Phsika
    How can i learn table Name in database an how can i learn any Table's Column name? SELECT Col.COLUMN_NAME, Col.DATA_TYPE FROM INFORMATION_SCHEMA.COLUMNS AS Col LEFT OUTER JOIN INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE AS Usg ON Col.TABLE_NAME = Usg.TABLE_NAME AND Col.COLUMN_NAME = Usg.COLUMN_NAME LEFT OUTER JOIN INFORMATION_SCHEMA.TABLE_CONSTRAINTS AS Con ON Usg.CONSTRAINT_NAME = Con.CONSTRAINT_NAME WHERE Col.TABLE_NAME = 'Addresses_Temp' AND Con.Constraint_TYPE = 'PRIMARY KEY' But it returns to me empty data:(

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  • Why can't you 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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  • Multiple Foriegn Keys from One Table linking to single Primary Key in second Table

    - by croker10
    Hi all, I have a database with three tables, a household table, an adults table and a users table. The Household table contains two foreign keys, iAdult1ID and iAdult2ID. The Users table has a iUserID primary key and the Adult table has a corresponding iUserID foreign key. One of the columns in the Users table is strUsername, an e-mail address. I am trying to write a query that will allow me to search for an e-mail address for either adult that has a relation to the household. So I have two questions, assuming that all the values are not null, how can I do this? And two, in reality, iAdult2ID can be null, is it still possible to write a query to do this? Thanks for your help. Let me know if you need any more information.

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  • Using NULL in MySQL

    - by JPro
    The data in my dabatase comes from an external source and where ever there is no data passed, I keep NULL in those places. Can anyone tell me if there are any implications in using NULL to represent empty value? Should I follow some other convention like 'data_not_available'? or something like that? Can anyone suggest?

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  • Relation to multiple tables of different types for rating?

    - by Tronic
    i have a table structure like this Products Team Images and want to implement a rating/commenting-feature, where users can rate each entry of all tables. what's the best way to make a single rating table? e.g. a user votes a a product and a team entry, and it should be possible to get alle these entries from a single table. what kind of table-structure is best for this purpose? i hope, my questions is clear enough :/ thanks in advance!

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  • Why would using a Temp table be faster than a nested query?

    - by Mongus Pong
    We are trying to optimise some of our queries. One query is doing the following: SELECT t.TaskID, t.Name as Task, '' as Tracker, t.ClientID, (<complex subquery>) Date, INTO [#Gadget] FROM task t SELECT TOP 500 TaskID, Task, Tracker, ClientID, dbo.GetClientDisplayName(ClientID) as Client FROM [#Gadget] order by CASE WHEN Date IS NULL THEN 1 ELSE 0 END , Date ASC DROP TABLE [#Gadget] (I have removed the complex subquery, cos I dont think its relevant other than to explain why this query has been done as a two stage process.) Now I would have thought it would be far more efficient to merge this down into a single query using subqueries as : SELECT TOP 500 TaskID, Task, Tracker, ClientID, dbo.GetClientDisplayName(ClientID) FROM ( SELECT t.TaskID, t.Name as Task, '' as Tracker, t.ClientID, (<complex subquery>) Date, FROM task t ) as sub order by CASE WHEN Date IS NULL THEN 1 ELSE 0 END , Date ASC This would give the optimiser better information to work out what was going on and avoid any temporary tables. It should be faster. But it turns out it is a lot slower. 8 seconds vs under 5 seconds. I cant work out why this would be the case as all my knowledge of databases imply that subqueries would always be faster than using temporary tables. Can anyone explain what could be going on!?!?

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  • Determine caller within stored proc or trigger

    - by Mike Clark
    I am working with an insert trigger within a Sybase database. I know I can access the @@nestlevel to determine whether I am being called directly or as a result of another trigger or procedure. Is there any way to determine, when the nesting level is deeper than 1, who performed the action causing the trigger to fire? For example, was the table inserted to directly, was it inserted into by another trigger and if so, which one.

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  • array insert in db

    - by gloris
    Hi, How best to put the array (100 or more length) in the database (MySQL)? I do not want multiple access to the database because it is so loaded. So my solution is as follows: string insert = "INSERT INTO programs (name, id) VALUES "; for(int i = 0; i < name.Length; i++) { if (i != 0) { insert = insert + ",("; } else { insert = insert + "("; } insert = insert + "'" + name[i] + "','" + id[i] + "'"; insert = insert + ")"; } //INSERT INTO programs (name, id) VALUES ('Peter','32'),('Rikko','343') .... But maybe is a faster version? Thanks

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  • How can I tell when a MySQL table was last updated?

    - by RaGE
    In the footer of my page, I would like to add something like "last updated the xx/xx/200x"; with this date being the last time a certain mySQL table has been updated. What is the best way to do that ? Is there a function to retrieve the date ? Should I make an access to the database everytime my footer is displayed ?

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  • Zend Framework Db Select Join table help

    - by tester2001
    I have this query: SELECT g.title, g.asin, g.platform_id, r.rank FROM games g INNER JOIN ranks r ON ( g.id = r.game_id ) ORDER BY r.rank DESC LIMIT 5` Now, this is my JOIN using Zend_Db_Select but it gives me array error $query = $this-select(); $query-from(array('g' = 'games'), array()); $query-join(array('r' = 'ranks'), 'g.id = r.game_id', array('g.title', 'g.asin', 'g.platform_id', 'r.rank')); $query-order('r.rank DESC'); $query-limit($top); $resultRows = $this-fetchAll($query); return $resultRows; Anyone know what I could be doing wrong? I want to get all the columns in 'games' to show and the 'rank' column in the ranks table.

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  • how to debug a query that has valid syntax, executes, but returns no results?

    - by Ty W
    So I'm writing a fairly involved query with a half dozen joins, a dependent subquery for [greatest-n-per-group] purposes, grouping, etc. It is syntactically valid, but I've clearly made at least one mistake because it returns nothing. In the past I've debugged valid queries that return nothing by removing joins, executing subqueries on their own, removing WHERE conditions, and removing grouping to see what I would get but so far this one has me stumped. Are there better tools or techniques to use for this sort of thing? This particular query is for MySQL if it matters for any platform-specific tools.

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  • How can I count existing and non-existing values with MySQL?

    - by jaya malladi
    I am new to MySQL. I have a table with answer ids. Answers can look like this:a1, a2, a3 ..., but due to some problems some are NULL, some are blank, and some are others like 1 a etc. Now I want to calculate the count of ids with a1 a2 a3 distinctly. But how is it possible to do this leaving others like NULL, blanks and garbage. The output should look like this atype count a1 45 a2 0 a3 56 If there is no row entry for a particular answer, the count should be 0.

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  • Why is Postgres doing a Hash in this query?

    - by Claudiu
    I have two tables: A and P. I want to get information out of all rows in A whose id is in a temporary table I created, tmp_ids. However, there is additional information about A in the P table, foo, and I want to get this info as well. I have the following query: SELECT A.H_id AS hid, A.id AS aid, P.foo, A.pos, A.size FROM tmp_ids, P, A WHERE tmp_ids.id = A.H_id AND P.id = A.P_id I noticed it going slowly, and when I asked Postgres to explain, I noticed that it combines tmp_ids with an index on A I created for H_id with a nested loop. However, it hashes all of P before doing a Hash join with the result of the first merge. P is quite large and I think this is what's taking all the time. Why would it create a hash there? P.id is P's primary key, and A.P_id has an index of its own.

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  • Load Empty Database table

    - by john White
    I am using SQLexpress and VS2008. I have a DB with a table named "A", which has an IdentitySpecification column named ID. The ID is auto-incremented. Even if the row is deleted, the ID still increases. After several data manipulation, the current ID has reached 15, for example. When I run the application if there's at least 1 row: if I add a new row, the new ID is 16. Everything is fine. If the table is empty (no row): if I add a new row, the new ID is 0, which is an error (I think). And further data manipulation (eg. delete or update) will result in an unhandled exception. Has anyone encountered this? PS. In my table definition, the ID has been selected as follow: Identity Increment = 1; Identity Seed =1; The DB load code is: dataSet = gcnew DataSet(); dataAdapter->Fill(dataSet,"A"); dataTable=dataSet->Tables["A"]; dbConnection->Open(); The Update button method dataAdapter->Update(dataSet,"tblInFlow"); dataSet->AcceptChanges(); dataTable=dataSet->Tables["tblInFlow"]; dataGrid->DataSource=dataTable; If I press Update: if there's at least a row: the datagrid view updates and shows the table correctly. if there's nothing in the table (no data row), the Add method will add a new row, but from ID 0. If I close the program and restart it again: the ID would be 16, which is correct. This is the add method row=dataTable->NewRow(); row["column1"]="something"; dataTable->Rows->Add(row); dataAdapter->Update(dataSet,"A"); dataSet->AcceptChanges(); dataTable=dataSet->Tables["A"];

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