Search Results

Search found 62701 results on 2509 pages for 'sql function'.

Page 805/2509 | < Previous Page | 801 802 803 804 805 806 807 808 809 810 811 812  | Next Page >

• Does introducing foreign keys to MySQL reduce performance

  - by Tam

  I'm building Ruby on Rails 2.3.5 app. By default, Ruby on Rails doesn't provide foreign key contraints so I have to do it manually. I was wondering if introducing foreign keys reduces query performance on the database side enough to make it not worth doing. Performance in this case is my first priority as I can check for data consistency with code. What is your recommendation in general? do you recommend using foreign keys? and how do you suggest I should measure this?

  Read the article

• Selecting records with specific month and year in SQL Server 2005

  - by John

  I want to list records with a particular month and year. The table name is 'Arrival' and 'date' is the field that stores the date that the record was added. This is to be done from a C# application. For example, if the user selects month as 'April' and year as '2009' in the application, it will list all the records that were added on April,2009. (I only need the query, hope I can figure out the rest :) )

  Read the article

• CakePHP repeats same queries

  - by Rytis

  I have a model structure: Category hasMany Product hasMany Stockitem belongsTo Warehouse, Manufacturer. I fetch data with this code, using containable to be able to filter deeper in the associated models: $this->Category->find('all', array( 'conditions' => array('Category.id' => $category_id), 'contain' => array( 'Product' => array( 'Stockitem' => array( 'conditions' => array('Stockitem.warehouse_id' => $warehouse_id), 'Warehouse', 'Manufacturer', ) ) ), ) ); Data structure is returned just fine, however, I get multiple repeating queries like, sometimes hundreds of such queries in a row, based on dataset. SELECT `Warehouse`.`id`, `Warehouse`.`title` FROM `beta_warehouses` AS `Warehouse` WHERE `Warehouse`.`id` = 2 Basically, when building data structure Cake is fetching data from mysql over and over again, for each row. We have datasets of several thousand rows, and I have a feeling that it's going to impact performance. Is it possible to make it cache results and not repeat same queries?

  Read the article

• Converting time/date from XML file into MYSQL format

  - by IconicDigital

  One of the affiliate networks provides a feed with the following time/date format. <startDate>1349992800000</startDate> <endDate>1355266799999</endDate> My problem is I am trying to convert this to a MYSQL format, I have tried mktime and strtotime with no luck the date seems to come out wrong. I know this is the time since the Equinox, I am just not sure how to convert this to a MYSQL format.

  Read the article

• How to check with PHP does a SQL database already have

  - by Dan Horvat

  I've tried to find the answer to this question but none of the answers fit. I have two databases, one has 15.000.000 entries and I want to extract the necessary data and store it in a much smaller database with around 33.000 entries. Both databases are open at the same time. Or at least they should be. While having the big database open and extracting the entries from it, is it possible to check whether the value already exists in the smaller database? I just need some generic way which checks that.

  Read the article

• PostgreSQL: How to index all foreign keys?

  - by biggusjimmus

  I am working with a large PostgreSQL database, and I are trying to tune it to get more performance. Our queries and updates seem to be doing a lot of lookups using foreign keys. What I would like is a relatively simple way to add Indexes to all of our foreign keys without having to go through every table (~140) and doing it manually. In researching this, I've come to find that there is no way to have Postgres do this for you automatically (like MySQL does), but I would be happy to hear otherwise there, too.

  Read the article

• Right way to implement a n-to-m related

  - by ThreeFingerMark

  Hello, this is a part from my database structure: Table: Item Columns: ItemID, Title, Content, Price Table: Tag Columns: TagID, Title Table: ItemTag Columns: ItemID, TagID Table: Image Columns: ImageID, Path, Size, UploadDate Table: ItemImage Columns: ItemID, ImageID The items can have more than one image so i have a extra table "Image" and map this images to an items. I see now a problem with this structure. Before i can add Images i must enter an item. My question is now. Is this structure a good way to solve my problem with many images / tags for one item? Thank you

  Read the article

• oracle search word in string

  - by Atul

  I want to search a word in string in ORACLE in which string is comma separated. Eg. String is ('MF1,MF2,MF3') and now I want to search whether 'MF' exists in that or not. If I am using instr('MF1,MF2,MF3','MF') it will give wrong result since I want to search Full MF in MF1 or MF2 or MF3.

  Read the article

• How do I select a fixed number of rows for each group?

  - by Maiasaura

  Here is some example data in a mysql table a b distance 15 44 250 94 31 250 30 41 250 6 1 250 95 18 250 72 84 500 14 23 500 55 24 500 95 8 500 59 25 500 40 73 500 65 85 500 32 50 500 31 39 500 22 25 500 37 11 750 98 39 750 15 57 750 9 22 750 14 44 750 69 22 750 62 50 750 89 35 750 67 65 750 74 37 750 52 36 750 66 53 750 82 74 1000 79 22 1000 98 41 1000 How do I query this table such that I get 2 rows per distance selected at random? A successful query will produce something like a b distance 30 41 250 95 18 250 59 25 500 65 85 500 15 57 750 89 35 750 79 22 1000 98 41 1000

  Read the article

• Getting counts of 0 from a query with a double group by

  - by Maltiriel

  I'm trying to write a query that gets the counts for a table (call it item) categorized by two different things, call them type and code. What I'm hoping for as output is the following: Type Code Count 1 A 3 1 B 0 1 C 10 2 A 0 2 B 13 2 C 2 And so forth. Both type and code are found in lookup tables, and each item can have just one type but more than one code, so there's also a pivot (aka junction or join) table for the codes. I have a query that can get this result: Type Code Count 1 A 3 1 C 10 2 B 13 2 C 2 and it looks like (with join conditions omitted): SELECT typelookup.name, codelookup.name, COUNT(item.id) FROM typelookup LEFT OUTER JOIN item JOIN itemcodepivot RIGHT OUTER JOIN codelookup GROUP BY typelookup.name, codelookup.name Is there any way to alter this query to get the results I'm looking for? This is in MySQL, if that matters. I'm not actually sure this is possible all in one query, but if it is I'd really like to know how. Thanks for any ideas.

  Read the article

• MySQL Query, how to group and count in one row ?

  - by Akarun

  Hi All, To simplify, I have tree tables: products, products-vs-orders, orders products fields : 'ProductID', 'Name', 'isGratis', ... products-vs-orders fields : 'ProductID', 'OrderID' orders fields : 'OrderID', 'Title', ... Actually, I have a query like this: SELECT orders.OrderID, orders.Title, COUNT(`products`.`isGratis`) AS "Quantity", `products`.`isGratis` FROM `orders`, `products-vs-orders`, `products` WHERE `orders`.`OrderID` = `products-vs-orders`.`OrderID` AND `products-vs-orders`.`ProductID` = `products`.`ProductID` GROUP BY `products`.`PackID`, `products`.`isGratis` This query works and return this surch of result: OrderID, Title, Quantity, isGratis 1 My Order 20 0 1 My Order 3 1 2 An other 8 0 2 An other 1 1 How can I retrieve the count of products 'gratis' and 'paid' in to separate cols ? OrderID, Title, Qt Paid, Qt Gratis 1 My Order 20 3 2 An other 8 1 Thanks for your help

  Read the article

• Why is doing a top(1) on an indexed column in mssql slow?

  - by reinier

  I'm puzzled by the following. I have a DB with around 10 million rows, and (among other indices) on 1 column is an index. Now I have 700k rows where the campaignid is indeed 3835 For all these rows, the connectionid is the same. I just want to find out this connectionid. use messaging_db; SELECT TOP (1) connectionid FROM outgoing_messages WITH (NOLOCK) WHERE (campaignid_int = 3835) Now this query takes approx 30 seconds to perform! I (with my small db knowledge) would expect that it would take any of the rows, and return me that connectionid If I test this same query for a campaign which only has 1 entry, it goes really fast. So the index works. How would I tackle this and why does this not work?

  Read the article

• Arranging VS2008 generated LinqToSql/EntityFramework data models/contexts in assemblies.

  - by JMSA

  What pattern should I use for data-access in case of VS2008 generated L2s or EF DataModels? Repository-pattern or what? As we know VS2008 generates Data-Models and DataContexts/ObjectContexts in the same file, then, how should I arrange my VS2008 assemblies in my VS2008 solution to achieve a layered design? If I use repository pattern, how should I arrange my assemblies in the VS2008 solution (as Data-Models and Data/Object-Contexts are stored in the same file...)? Any web/example link would be appreciated.

  Read the article

• DB Cursor fetching in Web Applications

  - by Alix Axel

  I never understood this: in web development whe[n|re] does it make sense to fetch results one by one? I mean, why should I use PDOStatement->fetch*() when I can use PDOStatement->fetchAll()?

  Read the article

• How do I choose a database?

  - by liamzebedee

  I need a comparison table of some sort for database varieties (MySQL, SQLite etc.). I can't find one. My use case is, I am implementing storage of objects in a distributed hash table. I need a database solution that is: Fast for sorting Simplistic (no users, preferably no additional structures like multiple tables etc.) Concurrent (if possible) Multi-platform File based (not stored in memory primarily) Centralized I will be programming in Go. As I understand, I believe I need what is called a Document Orientated Database, because I am storing objects, identified by keys. EDIT: While I am implementing a DHT, I will also be storing metadata about the objects, such as access counts etc. It would also be preferable to have TLL (time to live)

  Read the article

• Java Prepared Statement Error

  - by Suresh S

  Hi Guys the following code throws me an error i have an insert statement created once and in the while loop i am dynamically setting parameter , and at the end i says ps2.addBatch() again while ( (eachLine = in.readLine()) != null)) { for (int k=stat; k <=45;k++) { ps2.setString (k,main[(k-2)]); } stat=45; for (int l=1;l<= 2; l++) { ps2.setString((stat+l),pdp[(l-1)]);// Exception } ps2.addBatch(); } This is the error java.lang.ArrayIndexOutOfBoundsException: 45 at oracle.jdbc.dbaccess.DBDataSetImpl._getDBItem(DBDataSetImpl.java:378) at oracle.jdbc.dbaccess.DBDataSetImpl._createOrGetDBItem(DBDataSetImpl.java:781) at oracle.jdbc.dbaccess.DBDataSetImpl.setBytesBindItem(DBDataSetImpl.java:2450) at oracle.jdbc.driver.OraclePreparedStatement.setItem(OraclePreparedStatement.java:1155) at oracle.jdbc.driver.OraclePreparedStatement.setString(OraclePreparedStatement.java:1572) at Processor.main(Processor.java:233)

  Read the article

• Choosing between a union and a boolean condition

  - by bread

  Does this require a UNION? SELECT vend_id, prod_id, prod_price FROM products WHERE prod_price <= 5 UNION SELECT vend_id, prod_id, prod_price FROM products WHERE vend_id IN (1001,1002); Or is it the same if you do it this way? SELECT vend_id, prod_id, prod_price FROM products WHERE prod_price <= 5 OR vend_id IN (1001,1002);

  Read the article

• Should I make sure arguments aren't null before using them in a function.

  - by Nathan W

  The title may not really explain what I'm really trying to get at, couldn't really think of a way to describe what I mean. I was wondering if it is good practice to check the arguments that a function accepts for nulls or empty before using them. I have this function which just wraps some hash creation like so. Public Shared Function GenerateHash(ByVal FilePath As IO.FileInfo) As String If (FilePath Is Nothing) Then Throw New ArgumentNullException("FilePath") End If Dim _sha As New Security.Cryptography.MD5CryptoServiceProvider Dim _Hash = Convert.ToBase64String(_sha.ComputeHash(New IO.FileStream(FilePath.FullName, IO.FileMode.Open, IO.FileAccess.Read))) Return _Hash End Function As you can see I just takes a IO.Fileinfo as an argument, at the start of the function I am checking to make sure that it is not nothing. I'm wondering is this good practice or should I just let it get to the actual hasher and then throw the exception because it is null.? Thanks.

  Read the article

• Oracle: What does `(+)` do in a WHERE clause?

  - by Jonathan Lonowski

  Found the following in an Oracle-based application that we're migrating (generalized): SELECT Table1.Category1, Table1.Category2, count(*) as Total, count(Tab2.Stat) AS Stat FROM Table1, Table2 WHERE (Table1.PrimaryKey = Table2.ForeignKey(+)) GROUP BY Table1.Category1, Table1.Category2 What does (+) do in a WHERE clause? I've never seen it used like that before.

  Read the article

• why datetime.now not work when I didn't use tolist?

  - by MemoryLeak

  When I use datacontext.News .Where(p => p.status == true) .Where(p => p.date <= DateTime.Now) .ToList(); the system will return no results; When I use datacontext.News .Where(p => p.status == true) .ToList() .Where(p => p.date <= DateTime.Now) .ToList(); system will return expected results. Can anyone tell me what's up? Thanks in advance !

  Read the article

• .NET/C# Drizzle database client

  - by FlappySocks

  I am planning to use Drizzle in my next C# Mono app. Since there is no C# client available for Drizzle, I thought I would have a stab at writing my own by converting the Java client, and then making it work with DBLinq. Having seen the Java client, I realise that it's a longer job that I had anticipated, and I don't have the time. Besides the Java client is not all that mature yet. Since there is an official Drizzle C client library (libdrizzle), writing a C# wrapper might be the best solution. Are there any tools available that can assist in generating the code for this?

  Read the article

• Alter multiple tables' columns length

  - by gdoron

  So, we just found out that 254 tables in our Oracle DBMS have one column named "Foo" with the wrong length- Number(10) instead of Number(3). That foo column is a part from the PK of the tables. Those tables have other tables with forigen keys to it. What I did is: backed-up the table with a temp table. Disabled the forigen keys to the table. Disabled the PK with the foo column. Nulled the foo column for all the rows. Restored all the above But now we found out it's not just couple of tables but 254 tables. Is there an easy way, (or at least easier than this) to alter the columns length? P.S. I have DBA permissions.

  Read the article

• Multiple foreign 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.

  Read the article

• Temporary intermediate table

  - by user289429

  In our project to generate massive reports in oracle we use some permanent table to hold intermediate results. For example to generate one report we run few queries and populate the table, at the final step we join the intermediate table with huge application tables. These intermediate tables are cleared for next report run. We have few concerns in performance areas. These intermediate tables are transactional and don't have statistics. Is it good idea to join these with application tables which are partitioned and have up to date statistics. We need these results stored in the intermediate tables to be available across requests from UI hence we are not in a position to use oracle provided temporary tables. Any thoughts on what could be done would be appreciated.

  Read the article

• Should searchable date fields in a database table always be indexed?

  - by Spencer Ruport

  If I have a field in a table of some date type and I know that I will always be searching it using comparisons like between, > or < and never = could there be a good reason not to add an index for it?

  Read the article

< Previous Page | 801 802 803 804 805 806 807 808 809 810 811 812  | Next Page >