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• Is adding indexes to a SQL Server ever a bad idea?

  - by Aerik

  We have a mid-size SQL Server based application that has no indexes defined. Not even on the the identity columns. I suggested to our moderately expensive application consultant that perhaps we might get better performance (particularly as our database grows) by creating some indexes on appropriate fields, and he said: "Indexes will significantly impact other areas of the application and customers should not create them under any circumstances." Anybody ever heard of anything like this? Are there ever circumstances where one should not create any indexes? I can see nothing special about this app - it's got int identity columns, then lots of string columns, bunch of relational tables but nothing special or weird that I can see. Thanks!

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• How do you get average of sums in SQL (multi-level aggregation)?

  - by paxdiablo

  I have a simplified table xx as follows: rdate date rtime time rid integer rsub integer rval integer primary key on (rdate,rtime,rid,rsub) and I want to get the average (across all times) of the sums (across all ids) of the values. By way of a sample table, I have (with consecutive identical values blanked out for readability): rdate rtime rid rsub rval ------------------------------------- 2010-01-01 00.00.00 1 1 10 2 20 2 1 30 2 40 01.00.00 1 1 50 2 60 2 1 70 2 80 02.00.00 1 1 90 2 100 2010-01-02 00.00.00 1 1 999 I can get the sums I want with: select rdate,rtime,rid, sum(rval) as rsum from xx where rdate = '2010-06-01' group by rdate,rtime,rid which gives me: rdate rtime rid rsum ------------------------------- 2010-01-01 00.00.00 1 30 (10+20) 2 70 (30+40) 01.00.00 1 110 (50+60) 2 150 (70+80) 02.00.00 1 190 (90+100) as expected. Now what I want is the query that will also average those values across the time dimension, giving me: rdate rtime ravgsum ---------------------------- 2010-01-01 00.00.00 50 ((30+70)/2) 01.00.00 130 ((110+150)/2) 02.00.00 190 ((190)/1) I'm using DB2 for z/OS but I'd prefer standard SQL if possible.

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• free sql script to get a list of countries, provinces/states and their cities.

  - by reggie

  I am working on a registration page for a php website as mysql as the backend database. I need a sql script to insert the list of countries with their associated provinces and the provinces with their associated cities. I need all the countries, provinces and cities all over the world which are related to each other. I can get the individual list of countries, provinces and cities but there is no list that relates them together.. any help appreciated.. thanks in advance.

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• How do I correctly model data in SQL-based databases that have some columns in common, but also have

  - by Brandon Weiss

  For instance, let's say I have a User model. Users have things like logins, passwords, e-mail addresses, avatars, etc. But there are two types of Users that will be using this site, let's say Parents and Businesses. I need to store some different information for the Parents (e.g. childrens' names, domestic partner, salaries, etc.) than for the Businesses (e.g. industry, number of employees, etc.), but also some of it is the same, like logins and passwords. How do I correctly structure this in a SQL-based database? Thanks!

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• Entity Framework 4 / POCO - Where to start?

  - by Basiclife

  Hi, I've been programming for a while and have used LINQ-To-SQL and LINQ-To-Entities before (although when using entities it has been on a Entity/Table 1-1 relationship - ie not much different than L2SQL) I've been doing a lot of reading about Inversion of Control, Unit of Work, POCO and repository patterns and would like to use this methodology in my new applications. Where I'm struggling is finding a clear, concise beginners guide for EF4 which doesn't assume knowledge of EF1. The specific questions I need answered are: Code first / model first? Pros/cons in regards to EF4 (ie what happens if I do code first, change the code at a later date and need to regenerate my DB model - Does the data get preserved and transformed or dropped?) Assuming I'm going code-first (I'd like to see how EF4 converts that to a DB schema) how do I actually get started? Quite often I've seen articles with entity diagrams stating "So this is my entity model, now I'm going to ..." - Unfortunately, I'm unclear if they're created the model in the designer, saved it to generate code then stopped any further auto-code generation -or- They've coded (POCO)? classes and the somehow imported them into the deisgner view? I suppose what I really need is an understanding of where the "magic" comes from and how to add it myself if I'm not just generating an EF model directly from a DB. I'm aware the question is a little vague but I don't know what I don't know - So any input / correction / clarification appreciated. Needless to say, I don't expect anyone to sit here and teach me EF - I'd just like some good tutorials/forums/blogs/etc. for complete entity newbies Many thanks in advance

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• How to find unique values in jagged array

  - by David Liddle

  I would like to know how I can count the number of unique values in a jagged array. My domain object contains a string property that has space delimitered values. class MyObject { string MyProperty; //e.g = "v1 v2 v3" } Given a list of MyObject's how can I determine the number of unique values? The following linq code returns an array of jagged array values. A solution would be to store a temporary single array of items, looped through each jagged array and if values do not exist, to add them. Then a simple count would return the unique number of values. However, was wondering if there was a nicer solution. db.MyObjects.Where(t => !String.IsNullOrEmpty(t.MyProperty)) .Select(t => t.Categories.Split(new char[] { ' ' }, StringSplitOptions.RemoveEmptyEntries)) .ToArray() Below is a more readable example: array[0] = { "v1", "v2", "v3" } array[1] = { "v1" } array[2] = { "v4", "v2" } array[3] = { "v1", "v5" } From all values the unique items are v1, v2, v3, v4, v5. The total number of unique items is 5. Is there a solution, possibly using linq, that returns either only the unique values or returns the number of unique values?

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• Why does Sql Server recommends creating an index when it already exist?

  - by Pierre-Alain Vigeant

  I ran a very basic query against one of our table and I noticed that the execution plan query processor is recommending that we create an index on a column The query is SELECT SUM(DATALENGTH(Data)) FROM Item WHERE Namespace = 'http://some_url/some_namespace/' After running, I get the following message // The Query Processor estimates that implementing the following index could improve the query cost by 96.7211%. CREATE NONCLUSTERED INDEX [<Name of Missing Index, sysname,>] ON [dbo].[Item] ([Namespace]) My problem is that I already have such index on that column: CREATE NONCLUSTERED INDEX [IX_ItemNamespace] ON [dbo].[Item] ( [Namespace] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] Why is Sql Server recommending me to create such index when it already exist?

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• What C#/SQL Server feature did someone show you that made you say Wow!

  - by Randy Minder

  It's late Friday afternoon, and my mind is checking out for the week. So I thought I'd ask a light-hearted, interesting, question. Yesterday a co-worker showed me how he managed to save quite a bit of code and improve code reuse through the use of an anonymous delegate and the use of the Action function. My first thought was, "Wow, I had no idea you could do that!". I'm curious what sort of things someone showed you, either in c# or SQL Server, that made you stop and think, "Wow!". Randy

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• SQL - How can I apply a "semi-unique" constraint?

  - by Erin Drummond

  Hi, I have a (simplified) table consisting of three columns: id INT PRIMARY KEY NOT NULL AUTO_INCREMENT, foreignID INT NOT NULL, name VARCHAR NOT NULL Basically, I would like to add a constraint (at the database level rather than at the application level) where it only possible for one unique 'name' to exist per foreignID. For example, given the data (id, foreignid, name): 1,1,Name1 2,1,Name2 3,1,Name3 4,2,Name1 5,2,Name2 I want the constraint to fail if the user tries to insert another 'Name3' under foreignId 1, but succeed if the user tries to insert 'Name3' under foreignId 2. For this reason I cannot simply make the whole column UNIQUE. I am having difficulty coming up with a SQL expression to achieve this, can anybody help me? Thanks

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• What might cause SQL error Cannot find the object "dbo.InspectionEvents" because it does not exist o

  - by mrtrombone

  Hi My ASP.Net app is periodically getting the error 'Cannot find the object dbo."XXXX" because it does not exist or you do not have permissions' when it tries to execute a specific stored procedure that writes to the database. I have seen a few forum posts about this issue but the strange thing is that the method works fine almost all of the time, just every now and then I see it in my error logs. Can anyone tell me why this might works Ok most of the time but occassionally fire the error? Application is C# using Enterprise Library 4.1 Data Access. Database is SQL Server 2005 Cheers

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• Login code sample which has been hacked via SQL Injection, although mysql_real_escape_string...

  - by artmania

  Hi friends, I use CodeIgniter, and having trouble with hacking :( is it possible to make SQL Injection to the login code below: function process_login() { $username = mysql_real_escape_string($this->input->post('username')); $password = mysql_real_escape_string(MD5($this->input->post('password'))); //Check user table $query = $this->db->getwhere('users', array('username'=>$username, 'password'=>$password)); if ($query->num_rows() > 0) { // success login data Am I using the mysql_real_escape_string wrong? or what? Appreciate helps!

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• Can MySQL / SQL's short hand of "Using" be used without saying "Inner Join" ?

  - by Jian Lin

  The following 2 statements are to join using gifts.giftID = sentgifts.giftID: mysql> select * from gifts, sentgifts using (giftID); ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'using (giftID)' at line 1 and the second one: mysql> select * from gifts INNER JOIN sentgifts using (giftID); +--------+------------+----------------+---------------------+--------+------------+--------+------+---------------------+ | giftID | name | filename | effectiveTime | sentID | whenSent | fromID | toID | trytryWhen | +--------+------------+----------------+---------------------+--------+------------+--------+------+---------------------+ | 2 | teddy bear | bear.jpg | 2010-04-24 04:36:03 | 4 | 2010-04-24 | NULL | 111 | 2010-04-24 03:10:42 | | 6 | beer | beer_glass.png | 2010-04-24 05:18:12 | 5 | 2010-03-03 | 11 | 22 | 2010-03-03 00:00:00 | | 6 | beer | beer_glass.png | 2010-04-24 05:18:12 | 6 | 2010-04-24 | 11 | 222 | 2010-04-24 03:54:49 | | 6 | beer | beer_glass.png | 2010-04-24 05:18:12 | 7 | 2010-04-24 | 1 | 2 | 2010-04-24 03:58:45 | +--------+------------+----------------+---------------------+--------+------------+--------+------+---------------------+ 4 rows in set (0.00 sec) Can the first statement also use the "using" shorthand? It seems that when it is used then the word "Inner Join" must be specified... but the first statement is actually an inner join?

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• How can I build my SQL query from these tables?

  - by vee

  Hi All, I'm thinking of building query from these 2 tables (on SQL Server 2008). I have 2 tables as shown below: Table 1 MemberId . MemberName . Percentage . Amount1 00000001 AAA 1.0 100 00000002 BBB 1.2 800 00000003 ZZZ 1.0 700 Table 2 MemberId . MemberName . Percentage . Amount2 00000002 BBB 1.5 500 00000002 BBB 1.6 100 00000002 BBB 1.6 150 The result I want is MemberId . MemberName . Percentage . Amount . NettAmount 00000001 AAA 1.0 100 100 00000002 BBB 1.2 800 50 <-- 800-(500+100+150) 00000002 BBB 1.5 500 500 00000002 BBB 1.6 650 650 00000003 ZZZ 1.0 700 700 50 comes from 800 in Table1 minus sum of Amount2 in table2 for MemberID=00000002 Plz someone help me to build the query to reach this result. Thank you in advance.

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• How can I make an SQL statement that finds unassociated records?

  - by William Calleja

  I have two tables as follows: tblCountry (countryID, countryCode) tblProjectCountry(ProjectID, countryID) The tblCountry table is a list of all countries with their codes and the tblProjectCountry table associates certain countries with certain projects. I need an SQL statement that gives me a list of the countries with their country code that do NOT have an associated record in the tblProjectCountry table. so far I got to here: SELECT tblCountry.countryID, tblCountry.countryCode FROM tblProjectCountry INNER JOIN tblCountry ON tblProjectCountry.countryID = tblCountry.countryID WHERE (SELECT COUNT(ProjectID) FROM tblProjectCountry WHERE (ProjectID = 1) AND (countryID = tblCountry.countryID)) = 0 The above statement parses as correct but doesn't give the exact result I'm looking for. Can anyone help?

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• In SQL, in what situation do we want to Index a field in a table, or 2 fields in a table at the same

  - by Jian Lin

  In SQL, it is obvious that whenever we want to do a search on millions of record, say CustomerID in a Transactios table, then we want to add an index for CustomerID. Is another situation we want to add an index to a field when we need to do inner join or outer join using that field as a criteria? Such as Inner join on t1.custumerID = t2.customerID. Then if we don't have an index on customerID on both tables, we are looking at O(n^2) because we need to loop through the 2 tables sequentially. If we have index on customerID on both tables, then it becomes O( (log n) ^ 2 ) and it is much faster. Any other situation where we want to add an index to a field in a table? What about adding index for 2 fields combined in a table. That is, one index, for 2 fields together?

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• What's the fastest way to check the availability of a SQL Server server?

  - by mwolfe02

  I have an MS Access program in use in multiple locations. It connects to MS SQL Server tables, but the server name is different in each location. I am looking for the fastest way to test for the existence of a server. The code I am currently using looks like this: ShellWait "sc \\" & ServerName & " qdescription MSSQLSERVER > " & Qt(fn) FNum = FreeFile() Open fn For Input As #FNum Line Input #FNum, Result Close #FNum Kill fn If InStr(Result, "SUCCESS") Then ... ShellWait: executes a shell command and waits for it to finish Qt: wraps a string in double quotes fn: temporary filename variable I run the above code against a list of server names (of which only one is normally available). The code takes about one second if the server is available and takes about 8 seconds for each server that is unavailable. I'd like to get both of these lower, if possible, but especially the fail case as this one happens most often.

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• XDocument.Parse fails due to resolution error, how to disable resolution

  - by Frank Krueger

  I am trying to parse the contents of http://feeds.feedburner.com/riabiz using XDocument.Parse(string) (because it gets cached in a DB.) However, it keeps failing with the below stack trace when it tries to resolve some URIs in that XML. I don't care about validation or any of that XML nonsense, I just want the structure parsed. How can I use XDocument without this URI resolution? System.ArgumentException: The specified path is not of a legal form (empty). at System.IO.Path.InsecureGetFullPath (System.String path) [0x00000] in :0 at System.IO.Path.GetFullPath (System.String path) [0x00000] in :0 at System.Xml.XmlResolver.ResolveUri (System.Uri baseUri, System.String relativeUri) [0x00000] in :0 at System.Xml.XmlUrlResolver.ResolveUri (System.Uri baseUri, System.String relativeUri) [0x00000] in :0 at Mono.Xml2.XmlTextReader.ReadStartTag () [0x00000] in :0 at Mono.Xml2.XmlTextReader.ReadContent () [0x00000] in :0 at Mono.Xml2.XmlTextReader.Read () [0x00000] in :0 at System.Xml.XmlTextReader.Read () [0x00000] in :0 at Mono.Xml.XmlFilterReader.Read () [0x00000] in :0 at Mono.Xml.XmlFilterReader.Read () [0x00000] in :0 at System.Xml.XmlReader.ReadEndElement () [0x00000] in :0 at System.Xml.Linq.XElement.LoadCore (System.Xml.XmlReader r, LoadOptions options) [0x00000] in :0 at System.Xml.Linq.XNode.ReadFrom (System.Xml.XmlReader r, LoadOptions options) [0x00000] in :0 ...

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• Understanding many to many relationships and Entity Framework

  - by Anders Svensson

  I'm trying to understand the Entity Framework, and I have a table "Users" and a table "Pages". These are related in a many-to-many relationship with a junction table "UserPages". First of all I'd like to know if I'm designing this relationship correctly using many-to-many: One user can visit multiple pages, and each page can be visited by multiple users..., so am I right in using many2many? Secondly, and more importantly, as I have understood m2m relationships, the User and Page tables should not repeat information. I.e. there should be only one record for each user and each page. But then in the entity framework, how am I able to add new visits to the same page for the same user? That is, I was thinking I could simply use the Count() method on the IEnumerable returned by a LINQ query to get the number of times a user has visited a certain page. But I see no way of doing that. In Linq to Sql I could access the junction table and add records there to reflect added visits to a certain page by a certain user, as many times as necessary. But in the EF I can't access the junction table. I can only go from User to a Pages collection and vice versa. I'm sure I'm misunderstanding relationships or something, but I just can't figure out how to model this. I could always have a Count column in the Page table, but as far as I have understood you're not supposed to design database tables like that, those values should be collected by queries... Please help me understand what I'm doing wrong...

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• [Sql-Server]what data type to use for password salt and hash values and what length?

  - by Pandiya Chendur

  I am generating salt and hash values from my passwords by using, string salt = CreateSalt(TxtPassword.Text.Length); string hash = CreatePasswordHash(TxtPassword.Text, salt); private static string CreateSalt(int size) { //Generate a cryptographic random number. RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider(); byte[] buff = new byte[size]; rng.GetBytes(buff); // Return a Base64 string representation of the random number. return Convert.ToBase64String(buff); } private static string CreatePasswordHash(string pwd, string salt) { string saltAndPwd = String.Concat(pwd, salt); string hashedPwd = FormsAuthentication.HashPasswordForStoringInConfigFile( saltAndPwd, "sha1"); return hashedPwd; } What datatype you would suggest for storing these values in sql server? Any suggestion... Salt:9GsPWpFD Hash:E778AF0DC5F2953A00B35B35D80F6262CDBB8567

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• Is SQL server the best DB for Storing and comparing images in database for a small ecommerce applica

  - by iecut

  I have been trying to create a small e-commerce web based application using MS Dot Net framework. The application will let the user allow to store the image of their product that they want to sell or purchase, then they will have the option to upload the image of a particular product and compare that image with the similar images in the database. So my two main concerns are: - Is MS SQL a good option to store and compare the images. - Is the any other better database that can do the same work with less complexity of work and that is also easy to integrate with MS dot net framework.

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• For SQL select returning more than 1 value, how are they sorted when Id is GUID?

  - by Chris F

  I'm wondering how MSSQL orders data that is returned from a query and the Id columns of the respective tables are all of type uniqueidentifier. I'm using NHibernate GuidComb when creating all of the GUIDs and do things like: Sheet sheet = sheetRepository.Get(_SheetGuid_); // has many lines items IList<SheetLineItem> lineItems = sheet.LineItems; I'm just trying to figure out how they'll be ordered when I do something like: foreach (SheetLineItem lineItem in lineItems) I can't see to find a good article on the way GUIDs are compared by SQL when being ordered, if that's what's happening.

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• Creating a triple store query using SQL - how to find all triples that have a common predicate and o

  - by Ankur

  I have a database that acts like a triple store, except that it is just a simple MySQL database. I want to select all triples that have a common predicate and object. Info about RDF and triples I can't seem to work out the SQL. If I had just a single predicate and object to match I would do: select TRIPLE from TRIPLES where PREDICATE="predicateName" and OBJECT="objectName" But if I have a list (HashMap) of many pairs of (predicateName,objectName) I am not sure what I need to do. Please let me know if I need to provide more info, I am not sure that I have made this quite clear, but I am wary of providing too much info and confusing the issue.

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• SQL Server Query Editors - any that warn of number of rows to be changed?

  - by ciaranarcher

  We're using SQL Server 2000 Query Analyser, and one issue we have is that very occasionally, when a user is updating our live database, they insert the incorrect/no(!) where clause. I know, not good, but it happens. Are there any editors that will warn of the number of rows that might be changed (if that is even possible) or even a way to configure an editor, if it is connected to a certain database, to prompt for confirmation before the query is run? We have a way to recover our data in the cases where we run an incorrect query, but it takes time, and I'm just seeing if there are any ways to catch the error, or at least give the user a second chance. Thanks in advance.

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• Problems finding classes in namespace and testing extend expected parent

  - by Matt

  So I am in the process of building a site in ASP.Net MVC, and in the process I am adding certain things to my Site.Master I want to make sure that all of my model classes extend a certain base class that contains all of the pieces the Site.Master needs to be operable. I want to test to make sure this assumption isn't broken (I believe this will save me time when I forget about it and can't figure out why a new combination isn't working.) I wrote a test that I thought would help with this, but I am running into two problems. First it isn't finding the one example model class I have so far in the LINQ call all of a sudden, I am admittedly still a bit new to LINQ. Second, I had it finding the class earlier, but I couldn't get it to verify that the class inherits from the base class. Here is the example test. [Test] public void AllModelClassesExtendAbstractViewModel() { var abstractViewModelType = typeof (AbstractViewModel); Assembly baseAssembly = Assembly.GetAssembly(abstractViewModelType); var modelTypes = baseAssembly.GetTypes() .Where(assemblyType => (assemblyType.Namespace.EndsWith("Models") && assemblyType.Name != "AbstractViewModel")) .Select(assemblyType => assemblyType); foreach (var modelType in modelTypes) { Assert.That(modelType.IsSubclassOf(abstractViewModelType), Is.True , modelType.Name + " does not extend AbstractViewModel"); } }

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• How to access GMAIL for storage in custom CRM SQL Server DB?

  - by Optimal Solutions

  I have a client who wants his custom-written CRM to be able to access his sales people's emails so that, effectively, a history of email conversations between customer and salesperson is stored inside the CRM's database. The CRM is written in VB 2008 and the database is SQL Server 2008. The only email these people use, in the shop and on the road, is GMAIL. Each sales person has their own GMAIL address. Thats how they operate. If they're on the road and respond to a customer's email inquiry about a product, they would like that email conversation to be stored in a table in the database. I think thats the part I cant wrap my head around. How to get access to the email data (knowing the user id and password) and doing so from VB 2008

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