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• Creating a foreign key in MySQL produces error:

  - by SnOrfus

  I'm trying to create a foreign key on a table in MySQL and I'm getting a strange error that there seems to be little info about in any of my searches. I'm creating the key with this (emitted from mysql workbench 5.2): ALTER TABLE `db`.`appointment` ADD CONSTRAINT `FK_appointment_CancellationID` FOREIGN KEY (`CancellationID` ) REFERENCES `db`.`appointment_cancellation` (`ID` ) ON DELETE NO ACTION ON UPDATE NO ACTION , ADD INDEX `FK_appointment_CancellationID` (`CancellationID` ASC) ; at which point I get the error: ERROR 1452: Cannot add or update a child row: a foreign key constraint fails (alarmtekcore., CONSTRAINT FK_lead_appointment_CancellationID FOREIGN KEY (CancellationID) REFERENCES lead_appointment_cancellation (`) I've checked here but there's no data in the table.

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• Can't get Sum() working in Northwind example

  - by Vince

  Hi, The following code is generating a runtime error and I have no idea why. from o in Orders group o by o.Employee into employeeOrders select new { employeeOrders.Key.EmployeeID, employeeOrders.Key.FirstName, Orders = from eord in employeeOrders orderby eord.OrderID select new { eord.OrderID, eord.OrderDate, OrderTotal=eord.OrderDetails.Sum (od => od.UnitPrice) } } The error is Member access 'System.Decimal UnitPrice' of 'LINQPad.User.OrderDetails' not legal on type 'LINQPad.User.Orders I've also tried this in VS2010 with a standard drag and drop data context and same thing. Thanks in advance

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• What's the difference between tsql and isql?

  - by wamp

  I saw this in this post,and is really confused

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• same Linq for two tables

  - by Diana

  I need to do something like this, My two tables have the same signature, but different class so It suppose to work but it is not working. var myTable; if (booleanVariable == true) { myTable = table1; } else { myTable = table2; } var myLinq1 = from p in myTable join r in myOtherTable select p; In this case, I have to initialize myTable I have tried also, var myTable= table2; if (booleanVariable == true) { myTable = table1; } var myLinq1 = from p in myTable join r in myOtherTable select p; then var is type table2, then it can't be changed to table1 type. I need help, I don't want to make a copy paste of all the code. the linq query is huge, and it s nested with 5 or 6 queries. also I have to do this on 12 different methods. Thanks a lot for your help.

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• How do I find the top N batters per year?

  - by Drew Stephens

  I'm playing around with the Lahman Baseball Database in a MySQL instance. I want to find the players who topped home runs (HR) for each year. The Batting table has the following (relevant parts) of its schema: +-----------+----------------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-----------+----------------------+------+-----+---------+-------+ | playerID | varchar(9) | NO | PRI | | | | yearID | smallint(4) unsigned | NO | PRI | 0 | | | HR | smallint(3) unsigned | YES | | NULL | | +-----------+----------------------+------+-----+---------+-------+ For each year, every player has an entry (between hundreds and 12k per year, going back to 1871). Getting the top N hitters for a single year is easy: SELECT playerID,yearID,HR FROM Batting WHERE yearID=2009 ORDER BY HR DESC LIMIT 3; +-----------+--------+------+ | playerID | yearID | HR | +-----------+--------+------+ | pujolal01 | 2009 | 47 | | fieldpr01 | 2009 | 46 | | howarry01 | 2009 | 45 | +-----------+--------+------+ But I'm interested in finding the top 3 from every year. I've found solutions like this, describing how to select the top from a category and I've tried to apply it to my problem, only to end up with a query that never returns: SELECT b.yearID, b.playerID, b.HR FROM Batting AS b LEFT JOIN Batting b2 ON (b.yearID=b2.yearID AND b.HR <= b2.HR) GROUP BY b.yearID HAVING COUNT(*) <= 3; Where have I gone wrong?

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• LINQ2SQL: how to merge two columns from the same table into a single list

  - by TomL

  this is probably a simple question, but I'm only a beginner so... Suppose I have a table containing home-work locations (cities) certain people use. Something like: ID(int), namePerson(string), homeLocation(string), workLocation(string) where homeLocation and workLocation can both be null. Now I want all the different locations that are used merged into a single list. Something like: var homeLocation = from hm in Places where hm.Home != null select hm.Home; var workLocation = from wk in Places where wk.Work != null select wk.Work; List<string> locationList = new List<string>(); locationList = homeLocation.Distinct().ToList<string>(); locationList.AddRange(workLocation.Distinct().ToList<string>()); (which I guess would still allow duplicates if they have the same value in both columns, which I don't really want...) My question: how this be put into a single LINQ statement? Thanks in advance for your help!

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• MySQL query to order by parent then child places

  - by Swanny

  I have a table of pages in my database, each page can have a parent as below: id parent_id title 1 0 Home 2 0 Sitemap 3 0 Products 4 3 Product 1 5 3 Product 2 6 4 Product 1 Review Page What would be the best MySQL query to select all pages ordered by parent then child then child again if there is more than one level, there will be a maximum of three levels. The above example would produce the desired order: Home Sitemap Products Product 1 Product 1 Review Page Product 2

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• When should I consider representing the primary-key ...?

  - by JMSA

  When should I consider representing the primary-key as classes? Should we only represent primary keys as classes when a table uses composite-key? For example: public class PrimaryKey { ... ... ...} Then private PrimaryKey _parentID; public PrimaryKey ParentID { get { return _parentID; } set { _parentID = value; } } And public void Delete(PrimaryKey id) {...} When should I consider storing data as comma-separated values in a column in a DB table rather than storing them in different columns?

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• Use appsettings connectionstring instead of connectionStrings in web config for datacontext designer

  - by bmutch

  I need to use the appsettings/key for my connection string in a web project, and want to re-use this for my connectionstring in the datacontext designer, but it seems all I can use there is the web.config's connectionStrings, so I have to have my DB location in 2 places in the web.config, how can I force the designer (dbml) to use the appsettings instead?

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• Why isn't the Cache invalidated after table update using the SqlCacheDependency?

  - by Jason

  I have been trying to get SqlCacheDependency working. I think I have everything set up correctly, but when I update the table, the item in the Cache isn't invalidated. Can you look at my code and see if I am missing anything? I enabled the Service Broker for the Sandbox database. I have placed the following code in the Global.asax file. I also restart IIS to make sure it is called. void Application_Start(object sender, EventArgs e) { SqlDependency.Start(ConfigurationManager.ConnectionStrings["SandboxConnectionString"].ConnectionString); } I have placed this entry in the web.config file: <system.web> <caching> <sqlCacheDependency enabled="true" pollTime="10000"> <databases> <add name="Sandbox" connectionStringName="SandboxConnectionString"/> </databases> </sqlCacheDependency> </caching> </system.web> I call this code to put the item into the cache: protected void CacheDataSetButton_Click(object sender, EventArgs e) { using (SqlConnection sqlConnection = new SqlConnection(ConfigurationManager.ConnectionStrings["SandboxConnectionString"].ConnectionString)) { using (SqlCommand sqlCommand = new SqlCommand("SELECT PetID, Name, Breed, Age, Sex, Fixed, Microchipped FROM dbo.Pets", sqlConnection)) { using (SqlDataAdapter sqlDataAdapter = new SqlDataAdapter(sqlCommand)) { DataSet petsDataSet = new DataSet(); sqlDataAdapter.Fill(petsDataSet, "Pets"); SqlCacheDependency petsSqlCacheDependency = new SqlCacheDependency(sqlCommand); Cache.Insert("Pets", petsDataSet, petsSqlCacheDependency, DateTime.Now.AddSeconds(10), Cache.NoSlidingExpiration); } } } } Then I bind the GridView with this code: protected void BindGridViewButton_Click(object sender, EventArgs e) { if (Cache["Pets"] != null) { GridView1.DataSource = Cache["Pets"] as DataSet; GridView1.DataBind(); } } Between attempts to DataBind the GridView, I change the table's values expecting it to invalidate the Cache["Pets"] item, but it seems to stay in the Cache indefinitely.

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• need help in c# for loops

  - by hala

  sory for that arabic part but i dont now englich much ?? ???? ?? ???? ???????? foreach(int i in array1) { Console.Writeln(i); } what is console ?? ???

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• determine if a restaurant is open now (like yelp does) using database, php, js

  - by vee

  i was wondering if anyone knows how yelp determines what restaurants are "open now"? i'm developing a similar application using html/javascript/php. i was going to have a column in my database for each day, with comma separated hours written in "2243" format (10:43 pm). so for example if a restaurant is open for lunch and dinner it might be "1100,1400,1700,2200". then i'd check (using js) if the current time falls in one of the ranges for the current day. i'd also like to be able to determine if a restaurant is "open tonight", "open late", etc. for those i guess i'd check whether the open range overlaps with certain ranges. is there a better way to do this? particularly, how to store the hours in the database and then determine if they overlap with a given set of hours. thanks.

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• Good strategy for copying a "sliding window" of data from a table?

  - by chiborg

  I have a MySQL table from a third-party application that has millions of rows and only one index - the timestamp of each entry. Now I want to do some heavy self-joins and queries on the data using fields other than the timestamp. Doing the query on the original table would bring the database to a crawl, adding indexes to the table is not an option. Additionally, I only need entries that are newer than one week. My current strategy for doing the queries efficiently is to use a separate table (aux_table) that has the necessary indexes. My questions are: Is there another way to do the queries? and if not, How do I update the data in the indexed table efficiently? So far I have found two approaches for updating aux_table: Truncate aux_table and insert the desired data from the original table. Not very efficient because all the indexes must be re-crated. Check for the biggest timestamp in aux_table and insert all entries with a greater or equal timestamp from the original table. Occasionally drop older entries. Only copying entries with greater timestamp leads to dropped entries (because of entries with same timestamp that were inserted into the original table after the last update).

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• MySQL: Count occurrences of known (or enumerated) distinct values

  - by Eilidh

  After looking at how to count the occurrences of distinct values in a field, I am wondering how to count the occurrences of each distinct value if the distinct values are known (or enumerated). For example, if I have a simple table - TrafficLight Colour ------------ ------ 1 Red 2 Amber 3 Red 4 Red 5 Green 6 Green where one column (in this case Colour) has known (or enumerated) distinct values, how could I return the count for each colour as a separate value, rather than as an array, as in the linked example. To return an array with a count of each colour (using the same method as in the linked example), the query would be something like SELECT Colour COUNT(*) AS ColourCount FROM TrafficLights GROUP BY Colour, and return an array - Colour ColourCount ------ ----------- Red 3 Amber 1 Green 2 What I would like to do is to return the count for each Colour AS a separate total (e.g. RedCount). How can I do this?

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• How Can i Create This Complicated Query ?

  - by mTuran

  Hi, I have 3 tables: projects, skills and project_skills. In projects table i hold project's general data. Second table skills i hold skill id and skill name also i have projects_skills table which is hold project's skill relationships. Here is scheme of tables: CREATE TABLE IF NOT EXISTS `project_skills` ( `project_id` int(11) NOT NULL, `skill_id` int(11) NOT NULL, KEY `project_id` (`project_id`), KEY `skill_id` (`skill_id`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_turkish_ci; CREATE TABLE IF NOT EXISTS `projects` ( `id` int(11) NOT NULL AUTO_INCREMENT, `employer_id` int(11) NOT NULL, `project_title` varchar(100) COLLATE utf8_turkish_ci NOT NULL, `project_description` text COLLATE utf8_turkish_ci NOT NULL, `project_budget` int(11) NOT NULL, `project_allowedtime` int(11) NOT NULL, `project_deadline` datetime NOT NULL, `total_bids` int(11) NOT NULL, `average_bid` int(11) NOT NULL, `created` datetime NOT NULL, `active` tinyint(1) NOT NULL, PRIMARY KEY (`id`), KEY `created` (`created`), KEY `employer_id` (`employer_id`), KEY `active` (`active`), FULLTEXT KEY `project_title` (`project_title`,`project_description`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_turkish_ci AUTO_INCREMENT=3 ; CREATE TABLE IF NOT EXISTS `skills` ( `id` int(11) NOT NULL AUTO_INCREMENT, `category` int(11) NOT NULL, `name` varchar(100) COLLATE utf8_turkish_ci NOT NULL, `seo_name` varchar(100) COLLATE utf8_turkish_ci NOT NULL, `total_projects` int(11) NOT NULL, PRIMARY KEY (`id`), KEY `seo_name` (`seo_name`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_turkish_ci AUTO_INCREMENT=224 ; I want to select projects with related skill names. I think i have to use JOIN but i don't know how can i do. Thanks

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• Clone DB table row through MVC in MSSQL

  - by sslepian

  Is there a simple solution for duplicating table rows in MSSQL as well as all table rows with foreign keys pointing to the cloned table row? I've got a "master" table and a bunch of "child" tables which have a foreign key into the ID of the master table. I need to not only create a perfect copy of the master table, but clone each and every child table referencing the master table. Is there a simpler way to do this than creating a new row in the master table, copying in the information from the row to be cloned, then going through each child table and doing the same with each row pointing to the cloned row in the master table? I'm using a MSSQL 2005 Database accessed through C# ASP.net MVC 1.0.

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• i need a query to retrieve the following constraint

  - by ANITHA

  I have the following tables and fields: +------------------+ +-------------------+ +---------------+ | Request | | RequestItem | | Item | +------------------+ +-------------------+ +---------------+ | + Requester_Name | | + Request_No | | + Item | +------------------+ +-------------------+ +---------------+ | + Request_No | | + Item | +------------------+ +-------------------+ I would like to filter the items which are selected under a particular request number, along with a specific requester name. How might I go about doing this?

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• how to get external variable value in dtsx package.

  - by Rishabh

  Hi, I am executing .dtsx package from c#, it was executing fine, if i am passing one variable value from c# code then how can i get it on .dtsx package for my ole db source query. Here is my c# code. string file = @"D:\CYNCZFuzzy\CYNCZFuzzy\Contact.dtsx"; package = app.LoadPackage(file, null); Variables vars = package.Variables; vars["User::parentContactID"].Value = 1028203; pkgResults = package.Execute(); string result = pkgResults.ToString(); I need this 1028203 value on my ole db source query, here my query. select cr.MasterContactID as ParentContactID, c.ID,C.FirstName, C.MiddleName, c.LastName, c.ID as FieldID from Contact c inner join ContactRelation cr on cr.SlaveContactID = c.ID where RelationshipID = 1 AND cr.MasterContactID = ? what I should write on ? for getting 1028203 value from c# page. Thanks in advance...

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• Using sqlalchemy to query using multiple column where in clause

  - by crunkchitis

  I'm looking to execute this query using sqlalchemy. SELECT name, age, favorite_color, favorite_food FROM kindergarten_classroom WHERE (favorite_color, favorite_food) IN (('lavender','lentil soup'),('black','carrot juice')); I only want kids that like (lavender AND lentil soup) OR (black and carrot juice). This is similar, but doesn't get me all of the way there: Sqlalchemy in clause

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• SqlServer2008 + expensive union all

  - by Tim Mahy

  Hi al, we have 5 tables over which we should query with user search input throughout a stored procedure. We do a union all of the similar data inside a view. Because of this the view can not be materialized. We are not able to change these 5 tables drastically (like creating a 6th table that contains the similar data of the 5 tables and reference that new one from the 5 tables). The query is rather expensive / slow what are our other options? It's allowed to think outside the box. Unfortunately I cannot give more information like the table/view/SP definition because of customer confidentiality... greetings, Tim

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• Single Query returning me 4 tables, How to get all of them back into dataset ?

  - by Shantanu Gupta

  How to fill multiple tables in a dataset. I m using a query that returns me four tables. At the frontend I am trying to fill all the four resultant table into dataset. Here is my Query. Query is not complete. But it is just a refrence for my Ques Select * from tblxyz compute sum(col1) suppose this query returns more than one table, I want to fill all the tables into my dataset I am filling result like this con.open(); adp.fill(dset); con.close(); Now when i checks this dataset. It shows me that it has four tables but only first table data is being displayed into it. rest 3 dont even have schema also. What i need to do to get desired output

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• how to query with child relations to same table and order this correctly

  - by robertpnl

  Hi, Take this table: id name sub_id --------------------------- 1 A (null) 2 B (null) 3 A2 1 4 A3 1 The sub_id column is a relation to his owm table, to column ID. subid --- 0:1 --- id Now I have the problem to make a correctly SELECT query to show that the child rows (which sub_id is not null) directly selected under his parent row. So this must be a correctly order: 1 A (null) 3 A2 1 4 A3 1 2 B (null) A normal SELECT order the id. But how or which keyword help me to order this correctly? JOIN isn't possible I think because I want to get all the rows seperated. Because the rows will be displayed on a Gridview (ASP.Net) with EntityDataSource but the child rows must be displayed directly under his parent. Thank you.

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• Padding a string in Postgresql with rpad without truncating it

  - by dmoebius

  Using Postgresql 8.4, how can I right-pad a string with blanks without truncating it when it's too long? The problem is that rpad truncates the string when it is actually longer than number of characters to pad. Example: SELECT rpad('foo', 5); ==> 'foo ' -- fine SELECT rpad('foo', 2); ==> 'fo' -- not good, I want 'foo' instead. The shortest solution I found doesn't involve rpad at all: SELECT 'foo' || repeat(' ', 5-length('foo')); ==> 'foo ' -- fine SELECT 'foo' || repeat(' ', 2-length('foo')); ==> 'foo' -- fine, too but this looks ugly IMHO. Note that I don't actually select the string 'foo' of course, instead I select from a column: SELECT colname || repeat(' ', 30-length(colname)) FROM mytable WHERE ... Is there a more elegant solution?

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• MySQL Database Design with Internationalization

  - by Some name

  Hello, I'm going to start work on a medium sized application, and i'm planning it's db design. One thing that I'm not sure about is this. I will have many tables which will need internationalization, such as: "membership_options, gender_options, language_options etc" Each of these tables will share common i18n fields, like: "title, alternative_title, short_description, description" In your opinion which is the best way to do it? Have an i18n table with the same fields for each of the tables that will need them? or do something like: Membership table Gender table ---------------- -------------- id | created_at id | created_at 1 - 22.03.2001 1 - 14.08.2002 2 - 22.03.2001 2 - 14.08.2002 General translation table ------------------------- record_id | table_name | string_name | alternative_title| .... |id_language 1 - membership regular null 1 (english) 1 - membership normale null 2 (italian) 1 - gender man null 1(english) 1 -gender uomo null 2(italian) This would avoid me repeating something like: membership_translation table ----------------------------- membership_id | name | alternative_title | id_lang 1 regular null 1 1 normale null 2 gender_translation table ----------------------------- gender_id | name | alternative_title | id_lang 1 man null 1 1 uomo null 2 and so on, so i would probably reduce the number of db tables, but i'm not sure about performance.I'm not much of a DB designer, so please let me know.

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• How can I perform this query between related tables without using UNION?

  - by jeremy

  Suppose I have two separate tables that I watch to query. Both of these tables has a relation with a third table. How can I query both tables with a single, non UNION based query? I want the result of the search to rank the results by comparing a field on each table. Here's a theoretical example. I have a User table. That User can have both CDs and books. I want to find all of that user's books and CDs with a single query matching a string ("awesome" in this example). A UNION based query might look like this: SELECT "book" AS model, name, ranking FROM book WHERE name LIKE 'Awesome%' UNION SELECT "cd" AS model, name, ranking FROM cd WHERE name LIKE 'Awesome%' ORDER BY ranking DESC How can I perform a query like this without the UNION? If I do a simple left join from User to Books and CDs, we end up with a total number of results equal to the number of matching cds timse the number of matching books. Is there a GROUP BY or some other way of writing the query to fix this?

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