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• Entity Framework and multi-tenancy database design

  - by Junto

  I am looking at multi-tenancy database schema design for an SaaS concept. It will be ASP.NET MVC - EF, but that isn't so important. Below you can see an example database schema (the Tenant being the Company). The CompanyId is replicated throughout the schema and the primary key has been placed on both the natural key, plus the tenant Id. Plugging this schema into the Entity Framework gives the following errors when I add the tables into the Entity Model file (Model1.edmx): The relationship 'FK_Order_Customer' uses the set of foreign keys '{CustomerId, CompanyId}' that are partially contained in the set of primary keys '{OrderId, CompanyId}' of the table 'Order'. The set of foreign keys must be fully contained in the set of primary keys, or fully not contained in the set of primary keys to be mapped to a model. The relationship 'FK_OrderLine_Customer' uses the set of foreign keys '{CustomerId, CompanyId}' that are partially contained in the set of primary keys '{OrderLineId, CompanyId}' of the table 'OrderLine'. The set of foreign keys must be fully contained in the set of primary keys, or fully not contained in the set of primary keys to be mapped to a model. The relationship 'FK_OrderLine_Order' uses the set of foreign keys '{OrderId, CompanyId}' that are partially contained in the set of primary keys '{OrderLineId, CompanyId}' of the table 'OrderLine'. The set of foreign keys must be fully contained in the set of primary keys, or fully not contained in the set of primary keys to be mapped to a model. The relationship 'FK_Order_Customer' uses the set of foreign keys '{CustomerId, CompanyId}' that are partially contained in the set of primary keys '{OrderId, CompanyId}' of the table 'Order'. The set of foreign keys must be fully contained in the set of primary keys, or fully not contained in the set of primary keys to be mapped to a model. The relationship 'FK_OrderLine_Customer' uses the set of foreign keys '{CustomerId, CompanyId}' that are partially contained in the set of primary keys '{OrderLineId, CompanyId}' of the table 'OrderLine'. The set of foreign keys must be fully contained in the set of primary keys, or fully not contained in the set of primary keys to be mapped to a model. The relationship 'FK_OrderLine_Order' uses the set of foreign keys '{OrderId, CompanyId}' that are partially contained in the set of primary keys '{OrderLineId, CompanyId}' of the table 'OrderLine'. The set of foreign keys must be fully contained in the set of primary keys, or fully not contained in the set of primary keys to be mapped to a model. The relationship 'FK_OrderLine_Product' uses the set of foreign keys '{ProductId, CompanyId}' that are partially contained in the set of primary keys '{OrderLineId, CompanyId}' of the table 'OrderLine'. The set of foreign keys must be fully contained in the set of primary keys, or fully not contained in the set of primary keys to be mapped to a model. The question is in two parts: Is my database design incorrect? Should I refrain from these compound primary keys? I'm questioning my sanity regarding the fundamental schema design (frazzled brain syndrome). Please feel free to suggest the 'idealized' schema. Alternatively, if the database design is correct, then is EF unable to match the keys because it perceives these foreign keys as a potential mis-configured 1:1 relationships (incorrectly)? In which case, is this an EF bug and how can I work around it?

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• Content Query Web Part - How do you OrderBy when you QueryOverride?

  - by Richard JP Le Guen

  How do you order items when you override the QueryOverride property of the Content Query Web Part? I have been given responsibility for a Web Part which extends the Content Query Web Part. The QueryOverride property of this Web Part is programmatically changed. Currently, the Web Part does not function as designed, as it does not order the items according to the appropriate field. If I add an <OrderBy> node to the QueryOverride property I get an error message along the lines of 'something wrong with the query this web part is...' and the Content Query Web Part doesn't seem to have an OrderBy property which I could use instead. The "QueryOverride property" part of this msdn article seems to suggest I should be able to add an <OrderBy> node to the QueryOverride but a number of web sites I've been reading suggest that this is not true. So, wow do you order items when you override the QueryOverride property of the Content Query Web Part?

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• Removing non-alphanumeric characters in an Access Field.

  - by Jacques Tardie

  I need to remove hyphens from a string in a large number of access fields. What's the best way to go about doing this? Currently, the entries are follow this general format: 2010-54-1 2010-56-1 etc. I'm trying to run append queries off of this field, but I'm always getting validation errors causing the query to fail. I think the cause of this failure is the hypens in the entries, which is why I need to remove them. I've googled, and I see that there are a number of formatting guides using vbscript, but I'm not sure how I can integrate vb into Access. It's new to me :) Thanks in advance, Jacques

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• How to retrieve only updated/new records since the last query in SQL?

  - by William Choi

  Hi all, I was asked to design a class for caching SQL query results. Calling the class' query method will query and cache the entire set of results at the first time; afterward, each subsequence query will retrieve only the updated portion, and will merge the result into the cache. If the class is required to be generic, i.e. NO knowledge about the db and the tables, do you have any idea? Is it possible, and how to retrieve only updated/new records since the last query? Thanks! William

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• How to test a lamda expression var query result is null?

  - by mike

  var query = from emp in dbEmp.Employees join dept in dbEmp.Departments on emp.DeptID equals dept.DeptID where dept.DepartmentName.Contains(this.TextBox1.Text) select new { EmpID = emp.EmpID, EmpName = emp.EmpName, Age = emp.Age, Address = emp.Address, DeptName = dept.DepartmentName }; if (query==null) Label1.Text = "no results match your search"; GridView1.DataSource = query; GridView1.DataBind(); Everything works in the right way, but the label doesn't show the message when query result returns null. The label can show without condition(querry==null). So how to test if a var query result returns nothing? Thanks

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• Pulling record from mySQL database only working for userid and not email

  - by user2908467

  This function works because I search by userid: private void showList_Click(object sender, EventArgs e) { int id = 0; for (int i = 0; i <= sqlClient.Count("UserList"); i++) { Dictionary<string, string> dik = sqlClient.Select("UserList", "userid = " + id); var lines = dik.Select(kv => kv.Key + ": " + kv.Value.ToString()); userList.AppendText(string.Join(Environment.NewLine, lines)); userList.AppendText(Environment.NewLine); userList.AppendText("--------------------------------------"); id++; } } This function does not work because I search by email: private void login_Click(object sender, EventArgs e) { string email = lemail.Text; Dictionary<string, string> dik = sqlClient.Select("UserList", "firstname = " + email); var lines = dik.Select(kv => kv.Key + ": " + kv.Value.ToString()); logged.AppendText(string.Join(Environment.NewLine, lines)); } This is the error message I receive when I click on the login button: 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 '@aol.com' at line 1 The email I searched for in the database was "[email protected]" without quotes. I'm lead to believe by the error message the @ sign is causing conflict as I know it is a special character but I am having a hard time figuring out what phrase to search for to help me. Also, here is the function that is being called: public Dictionary<string, string> Select(string table, string WHERE) { //This methods selects from the database, it retrieves data from it. //You must make a dictionary to use this since it both saves the column //and the value. i.e. "age" and "33" so you can easily search for values. //Example: SELECT * FROM names WHERE name='John Smith' // This example would retrieve all data about the entry with the name "John Smith" //Code = Dictionary<string, string> myDictionary = Select("names", "name='John Smith'"); //This code creates a dictionary and fills it with info from the database. string query = "SELECT * FROM " + table + " WHERE " + WHERE + ""; Dictionary<string, string> selectResult = new Dictionary<string, string>(); if (this.Open()) { MySqlCommand cmd = new MySqlCommand(query, conn); MySqlDataReader dataReader = cmd.ExecuteReader(); try { while (dataReader.Read()) { for (int i = 0; i < dataReader.FieldCount; i++) { selectResult.Add(dataReader.GetName(i).ToString(), dataReader.GetValue(i).ToString()); } } dataReader.Close(); } catch { } this.Close(); return selectResult; } else { return selectResult; } } My database table is called "UserList" The fields in order are as follows: userid, email, password, lastname, firstname Any help would be greatly appreciated. This site is amazing!

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• Adding a calculated field to a Query at run time.

  - by JamesB

  I'm getting data using a query in Delphi, and would like to add a calculated field to the query before it runs. The calculated field is using values in code as well as the query so I can't just calculate it in SQL. I know I can attach an OnCalcFields Event to actually make the calculation, but the problem is after adding the calculated field there are no other fields in the query... I did some digging and found that all of the field defs are created but the actual fields are only created if DefaultFields then CreateFields Default Fields is specified procedure TDataSet.DoInternalOpen; begin FDefaultFields := FieldCount = 0; ... end; Which would indicate that if you add fields you only get the fields you added. I would like all the fields in the query AS WELL AS the ones I Add. Is this possible or do I have to add all the fields I'm using as well?

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• How do I add a one-to-one relationship in MYSQL?

  - by alex

  +-------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------+-------------+------+-----+---------+-------+ | pid | varchar(99) | YES | | NULL | | +-------+-------------+------+-----+---------+-------+ 1 row in set (0.00 sec) +-------+---------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------+---------------+------+-----+---------+-------+ | pid | varchar(2000) | YES | | NULL | | | recid | varchar(2000) | YES | | NULL | | +-------+---------------+------+-----+---------+-------+ 2 rows in set (0.00 sec) This is my table. pid is just the id of the user. "recid" is a recommended song for that user. I hope to have a list of pid's, and then recommended songs for each person. Of course, in my 2nd table, (pid, recid) would be unique key. How do I do a one-to-one query for this ?

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• PostgreSQL - select only when specific multiple apperance in column

  - by Horse SMith

  I'm using PostgreSQL. I have a table with 3 fields person, recipe and ingredient person = creator of the recipe recipe = the recipe ingredient = one of the ingredients in the recipe I want to create a query which results in every person who whenever has added carrot to a recipe, the person must also have added salt to the same recipe. More than one person can have created the recipe, in which case the person who added the ingredient will be credited for adding the ingredient. Sometimes the ingredient is used more than once, even by the same person. If this the table: person1, rec1, carrot person1, rec1, salt person1, rec1, salt person1, rec2, salt person1, rec2, pepper person2, rec1, carrot person2, rec1, salt person2, rec2, carrot person2, rec2, pepper person3, rec1, sugar person3, rec1, carrot Then I want this result: person1 Because this person is the only one who whenever has added carrot also have added salt.

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• How to connect 2 mysql tables with 2 connection string

  - by denonth

  Hi all I need to connect 2 tables from 2 mysql databases that have 2 different connection strings and each is on the different server. I have this query: cmd = new MySqlCommand(String.Format("INSERT INTO {0} (a,b,c,d) SELECT (a,b,c,d) FROM {1}", ConfigSettings.ReadSetting("main_table"), ConfigSettings.ReadSetting("main_table")), con); So both table have the same columns. Thats why I have only one ConfigSettings.ReadSetting("main_table") for both of them as they are same. I have 2 connection strings and each is pointing to their server: con.ConnectionString = ConfigurationManager.ConnectionStrings["con1"].ConnectionString; con2.ConnectionString = ConfigurationManager.ConnectionStrings["con2"].ConnectionString; How to make this cmd to be workking with 2 different connection strings and with the same name for the table. Table name will change that's why it is saved in config.

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• Fastest way to do a weighted tag search in SQL Server

  - by Hasan Khan

  My table is as follows ObjectID bigint Tag nvarchar(50) Weight float Type tinyint I want to get search for all objects that has tags 'big' or 'large' I want the objectid in order of sum of weights (so objects having both the tags will be on top) select objectid, row_number() over (order by sum(weight) desc) as rowid from tags where tag in ('big', 'large') and type=0 group by objectid the reason for row_number() is that i want paging over results. The query in its current form is very slow, takes a minute to execute over 16 million tags. What should I do to make it faster? I have a non clustered index (objectid, tag, type) Any suggestions?

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• sql combine two subqueries

  - by Claudiu

  I have two tables. Table A has an id column. Table B has an Aid column and a type column. Example data: A: id -- 1 2 B: Aid | type ----+----- 1 | 1 1 | 1 1 | 3 1 | 1 1 | 4 1 | 5 1 | 4 2 | 2 2 | 4 2 | 3 I want to get all the IDs from table A where there is a certain amount of type 1 and type 3 actions. My query looks like this: SELECT id FROM A WHERE (SELECT COUNT(type) FROM B WHERE B.Aid = A.id AND B.type = 1) = 3 AND (SELECT COUNT(type) FROM B WHERE B.Aid = A.id AND B.type = 3) = 1 so on the data above, just the id 1 should be returned. Can I combine the 2 subqueries somehow?

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• Trying to create fields based on a case statement

  - by dido

  I'm having some trouble with the query below. I am trying to determine if the "category" field is A, B or C and then creating a field based on the category. That field would sum up payments field. But I'm running into error saying "incorrect syntax near keyword As". I am creating this in a SQL View. Using SQL Server 2008 SELECT r.id, r.category CASE WHEN r.category = 'A' then SUM(r.payment) As A_payments WHEN r.category = 'B' then SUM(r.payment) As B_payments WHEN r.category = 'C' then SUM(r.payment) As C_payments END FROM r_invoiceTable As r GROUP BY r.id, r.category I have data where all of the above cases should be executed because the data that I have has A,B and C Sample Data- r_invoiceTable Id --- Category ---- Payment 222 A ---- 50 444 A ---- 30 111 B ---- 90 777 C ---- 20 555 C ---- 40 Desired Output A_payments = 80, B_payments = 90, C_payments = 60

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• SQL SERVER – What is AdventureWorks?

  - by pinaldave

  NOTE: If you know the answer of this question, then I request you to stop reading this post right now. Please do not leave comment about this blog post not being useful to you, if you knew the answer. Few days ago, I received DM asking What is an AdventureWorks database and why in all the examples I use that instead of any other database (e.g. Pubs or  Northwind)? As matter of fact, when I went back to my question list, which I have yet not answered, there were a few more variations of this same question. AdventureWorks is a Sample Database shipped with SQL Server and it can be downloaded from http://codeplex.com site. AdventureWorks has replaced Northwind and Pubs from the sample database in SQL Server 2005. The Microsoft team keeps updating the sample database as they release new versions. Here are some quick links: AdventureWorks SQL Server 2008 SR4 AdventureWorks 2008R2 November CTP AdventureWorks for SQL Azure (December CTP) AventureWorks for SQL Server 2005 SP2A SQL SERVER – 2008 – Download and Install Samples Database AdventureWorks 2005 – Detail Tutorial I have previously written few other articles on the same subject; you can find them easily here: [email protected] Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Documentation, SQL Download, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• SQL SERVER – FIX: ERROR Msg 5169, Level 16: FILEGROWTH cannot be greater than MAXSIZE for file

  - by pinaldave

  I am writing this blog post right after I resolve this error for one of the system. Recently one of the my friend who is expert in infrastructure as well private cloud was working on SQL Server installation. Please note he is seriously expert in what he does but he has never worked SQL Server before and have absolutely no experience with its installation. He was modifying database file and keep on getting following error. As soon as he saw me he asked me where is the maxfile size setting so he can change. Let us quickly re-create the scenario he was facing. Error Message: Msg 5169, Level 16, State 1, Line 1 FILEGROWTH cannot be greater than MAXSIZE for file ‘NewDB’. Creating Scenario: CREATE DATABASE [NewDB] ON PRIMARY (NAME = N'NewDB', FILENAME = N'D:\NewDB.mdf' , SIZE = 4096KB, FILEGROWTH = 1024KB, MAXSIZE = 4096KB) LOG ON (NAME = N'NewDB_log', FILENAME = N'D:\NewDB_log.ldf', SIZE = 1024KB, FILEGROWTH = 10%) GO Now let us see what exact command was creating error for him. USE [master] GO ALTER DATABASE [NewDB] MODIFY FILE ( NAME = N'NewDB', FILEGROWTH = 1024MB ) GO Workaround / Fix / Solution: The reason for the error is very simple. He was trying to modify the filegrowth to much higher value than the maximum file size specified for the database. There are two way we can fix it. Method 1: Reduces the filegrowth to lower value than maxsize of file USE [master] GO ALTER DATABASE [NewDB] MODIFY FILE ( NAME = N'NewDB', FILEGROWTH = 1024KB ) GO Method 2: Increase maxsize of file so it is greater than new filegrowth USE [master] GO ALTER DATABASE [NewDB] MODIFY FILE ( NAME = N'NewDB', FILEGROWTH = 1024MB, MAXSIZE = 4096MB) GO I think this blog post will help everybody who is facing similar issues. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Error Messages, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• Using json as database with EF, how can I link EF and the json file during DbContext initialization?

  - by blacai

  For a personal testing-project I am considering to create a SPA with the following technologies: ASP.NET MVC + EF + WebAPI + AngularJS. The project will make use of small amount of data, so I was thinking I could use just a .json file as storage. But I am not sure about how to proceed with the link between EF and the json file in the initialization of the DbContext. I found a stackoverflow related question: http://stackoverflow.com/questions/13899342/can-we-use-json-as-a-database I know the basics of edit files and store data inside. What I tried is to get the data from the json file in the initilizer method and create the objects one by one. This is more a doubt about how this works if I save/update an object in the dbcontext, do I need to go through all the elements and add/update it manually? Is it better to rewrite the complete file? According to this http://stackoverflow.com/questions/7895335/append-data-to-a-json-file-with-php it is not a good practice to use json/XML for data wich will be manipulated. Anyone has experience with anything similar? Is this a really bad idea and I should use another kind of data-storage?

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• In an online questionnaire, what is a best way to design a database for keeping track of users all attempts?

  - by user1990525

  We have a web app where users can take online exams. Exam admin will create a questionnaire. A questionnaire can have many Questions. Each question is a multiple choice question (MCQ). Lets say an admin creates a questionnaire with 10 questions. Users attempt those questions. Now, unlike real exams users can attempt single questionnaire multiple times. And we have to keep track of his all attempts. e.g. User_id Questionnaire_id question_id answer attempt_date attempt_no 1 1 1 a 1 June 2013 1 1 1 2 b 1 June 2013 1 1 1 1 c 2 June 2013 2 1 1 2 d 2 June 2013 2 Now it can also happen that after user has attempted same questionnare twice, admin can delete a question from same questionnaire, but users attempt history should still have reference to that so that user can see his that question in his attempt history in spite of admin deleting that question. If user now attempts this changed questionnaire he should see only 1 question. User_id Questionnaire_id question_id answer attempt_date attempt_no 1 1 1 a 3 June 2013 3 Also, after this user modified some part of question, users attempt history should show question before modification while any new attempt should show modified question. How do we manage this at the database level? My first gut feeling was that, For deletes, do not do physical delete, just make a question inactive so that history can still keep track of users attempt. For modifications, create versions for questions and each new attempt refres to latest version of each question and history keeping reference to version of question at attempt time.

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• Would this data requirement suit a Document -Oriented database?

  - by codecowboy

  I have a requirement to allow users to fill in journal/diary entries per day. I want to provide a handful of known journal templates with x columns to fill in. An example might be a thought diary; a user has to record a thought in one column, describe the situation, rate how they felt etc. The other requirement is that a user should be able to create their own diary templates. They might have a need for a 10 column diary entry per day and might need to rate some aspect out of 50 instead of 10. In an RDBMS, I can see this getting quite complicated. I could have individual tables for my known templates as the fields will be fixed. But for custom diary templates I imagine I would would need a table storing custom_field_types (the diary columns), a table storing entries referencing their field types (custom_entries) and then a third custom_diary table which would store rows matching custom_entries to diaries. Leaving performance / scaling aside, would it be any simpler or make more sense to use a document oriented database like MongoDB to store this data? This is for a web application which might later need an API for mobile devices.

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• Database development/admin - What exactly should I be trying to learn? [closed]

  - by Sauron

  I've been a bit weary about approaching learning databases. I've dabbled into them before, and "DATA" in itself appeals to me a lot. Maintaining/searching/moving, everything about it in the abstract sense I love. (This isn't a career question, this is a learning question.) But as RDBMS's begin to be easier to maintain, and with tools that "anyone" can use to manage data I feared for the database admin jobs. (Yet I see jobs for SQL everywhere!). I know "No-SQL" was a big deal but it kinda has its niche. But that leaves me here... unsure of really "what" to study. What tools should I have in my tool belt? I'm sure RDBMS's will be around in both use and maintaining legacy code. But what else? Obviously data will always be around, but is this a secure field or a dying one? And what should I be concentrating on?

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• Migrating SQL Server Compact Edition (SQL CE) database to SQL Server using Web Matrix

  - by Harish Ranganathan

  One of the things that is keeping us busy is the Web Camps we are delivering across 5 cities.  If you are a reader of this blog, and also attended one of these web camps, there is a good chance that you have seen me since I was there in all the places, so far.  The topics that we cover include Visual Studio 2010 SP1, SQL CE, ASP.NET MVC & HTML5.  Whenever I talk about SQL CE, the immediate response is that, people are wow that Microsoft has shipped a FREE compact edition database, which is an embedded database that can be x-copy deployed.  If you think, well didn’t Microsoft ship SQL Express which is FREE?  The difference is that, SQL Express runs as a service in the machine (if you open SQL Configuration Manager, you can notice that SQL Express is running as a service along with your SQL Server Engine (if you have installed ).  This makes it that, even if you are willing to use SQL Express when you deploy your application, it needs to be installed on the production machine (hosting provider) and it needs to run as a service.  Many hosters don’t allow such services to run on their space. SQL CE comes as a x-Copy deploy-able database with just a few DLLs required to run it on the machine and they don’t even need to be installed in GAC on the production machine.  In fact, if you have Visual Studio 2010 SP1 installed, you can use the “Add Deployable Dependencies” option in Project-Properties and it would detect that SQL CE is something you would probably want to add as a deploy-able dependency for your project.  With that, it bundles the required DLLs as a part of the “_bin_deployableAssemblies” folder.  So your project can be x-Copy deployed and just works fine. However, SQL CE has the limit of 4GB storage space.  Real world applications often require more than just 4GB of data storage and it often turns out that people would like to use SQL CE for development/ramp up stages but would like to migrate to full fledged SQL Server after a while.  So, its only natural that the question arises “How do I move my SQL CE database to SQL Server”  And honestly, it doesn’t come across as a straight forward support.  I was talking to Ambrish Mishra (PM in SQL CE Team, Hyderabad) since I got this question in almost all the places where we talked about SQL CE.   He was kind enough to demonstrate how this can be accomplished using Web Matrix.  Open Web Matrix (Web Matrix can be installed for free from www.microsoft.com/web) and click on “Site from Template” Click on the “Bakery” template (since by default it uses a SQL CE database and has all the required sample data) and click “Ok”. In the project, you can navigate to the Database tab and will be able to find that the Bakery site uses a SQL CE database “bakery.sdf” Select the “bakery.sdf” and you will be able to see the “Migrate” button on the top right Once you click on the “Migrate” button, you will notice that the popup wizard opens up and by default is configured for SQL Express.  You can edit the same to point to your local SQL Server instance, or a remote server. Upon filling in the Server Name, Username and Password, when you click “Ok”, couple of things happen.  1. The database is migrated to SQL Server (local or remote – subject to permissions on remote server).   You can open up SQL Server Management Studio and connect to the server to verify that the “bakery” database exists under “Databases” node. 2. You can also notice that in Web Matrix, when you navigate to the “Files” tab and open up the web.config file, connection string now points to the SQL Server instance (yes, the Migrate button was smart enough to make this change too ) And there it is, your SQL Server Compact Edition database, now migrated to SQL Server!! In a future post, I would explain the steps involved when using Visual Studio. Cheers !!!

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• Blueprints for Oracle NoSQL Database

  - by dan.mcclary

  I think that some of the most interesting analytic problems are graph problems.  I'm always interested in new ways to store and access graphs.  As such, I really like the work being done by Tinkerpop to create Open Source Software to make property graphs more accessible over a wide variety of datastores.  Since key-value stores like Oracle NoSQL Database are well-suited to storing property graphs, I decided to extend the Blueprints API to work with it.  Below I'll discuss some of the implementation details, but you can check out the finished product here: http://github.com/dwmclary/blueprints-oracle-nosqldb.  What's in a Property Graph?  In the most general sense, a graph is just a collection of vertices and edges.  Vertices and edges can have properties: weights, names, or any number of other traits.  In an undirected graph, edges connect vertices without direction.  A directed graph specifies that all edges have a head and a tail --- a direction.  A multi-graph allows multiple edges to connect two vertices.  A "property graph" encompasses all of these traits. Key-Value Stores for Property Graphs Key-Value stores like Oracle NoSQL Database tend to be ideal for implementing property graphs.  First, if any vertex or edge can have any number of traits, we can treat it as a hash map.  For example: Vertex["name"] = "Mary" Vertex["age"] = 28 Vertex["ID"] = 12345  and so on.  This is a natural key-value relationship: the key "name" maps to the value "Mary."  Moreover if we maintain two hash maps, one for vertex objects and one for edge objects, we've essentially captured the graph.  As such, any scalable key-value store is fertile ground for planting graphs. Oracle NoSQL Database as a Scalable Graph Database While Oracle NoSQL Database offers useful features like tunable consistency, what lends it to storing property graphs is the storage guarantees around its key structure.  Keys in Oracle NoSQL Database are divided into two parts: a major key and a minor key.  The storage guarantee is simple.  Major keys will be distributed across storage nodes, which could encompass a large number of servers.  However, all minor keys which are children of a given major key are guaranteed to be stored on the same storage node.  For example, the vertices: /Personnel/Vertex/1  and /Personnel/Vertex/2 May be stored on different servers, but /Personnel/Vertex/1-/name and  /Personnel/Vertex/1-/age will always be on the same server.  This means that we can structure our graph database such that retrieving all the properties for a vertex or edge requires I/O from only a single storage node.  Moreover, Oracle NoSQL Database provides a storeIterator which allows us to store a huge number of vertices and edges in a scalable fashion.  By storing the vertices and edges as major keys, we guarantee that they are distributed evenly across all storage nodes.  At the same time we can use a partial major key to iterate over all the vertices or edges (e.g. we search over /Personnel/Vertex to iterate over all vertices). Fork It! The Blueprints API and Oracle NoSQL Database present a great way to get started using a scalable key-value database to store and access graph data.  However, a graph store isn't useful without a good graph to work on.  I encourage you to fork or pull the repository, store some data, and try using Gremlin or any other language to explore.

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• Normalizing Item Names & Synonyms

  - by RabidFire

  Consider an e-commerce application with multiple stores. Each store owner can edit the item catalog of his store. My current database schema is as follows: item_names: id | name | description | picture | common(BOOL) items: id | item_name_id | picture | price | description | picture item_synonyms: id | item_name_id | name | error(BOOL) Notes: error indicates a wrong spelling (eg. "Ericson"). description and picture of the item_names table are "globals" that can optionally be overridden by "local" description and picture fields of the items table (in case the store owner wants to supply a different picture for an item). common helps separate unique item names ("Jimmy Joe's Cheese Pizza" from "Cheese Pizza") I think the bright side of this schema is: Optimized searching & Handling Synonyms: I can query the item_names & item_synonyms tables using name LIKE %QUERY% and obtain the list of item_name_ids that need to be joined with the items table. (Examples of synonyms: "Sony Ericsson", "Sony Ericson", "X10", "X 10") Autocompletion: Again, a simple query to the item_names table. I can avoid the usage of DISTINCT and it minimizes number of variations ("Sony Ericsson Xperia™ X10", "Sony Ericsson - Xperia X10", "Xperia X10, Sony Ericsson") The down side would be: Overhead: When inserting an item, I query item_names to see if this name already exists. If not, I create a new entry. When deleting an item, I count the number of entries with the same name. If this is the only item with that name, I delete the entry from the item_names table (just to keep things clean; accounts for possible erroneous submissions). And updating is the combination of both. Weird Item Names: Store owners sometimes use sentences like "Harry Potter 1, 2 Books + CDs + Magic Hat". There's something off about having so much overhead to accommodate cases like this. This would perhaps be the prime reason I'm tempted to go for a schema like this: items: id | name | picture | price | description | picture (... with item_names and item_synonyms as utility tables that I could query) Is there a better schema you would suggested? Should item names be normalized for autocomplete? Is this probably what Facebook does for "School", "City" entries? Is the first schema or the second better/optimal for search? Thanks in advance! References: (1) Is normalizing a person's name going too far?, (2) Avoiding DISTINCT

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• Muti-Schema Privileges for a Table Trigger in an Oracle Database

  - by sisslack

  I'm trying to write a table trigger which queries another table that is outside the schema where the trigger will reside. Is this possible? It seems like I have no problem querying tables in my schema but I get: Error: ORA-00942: table or view does not exist when trying trying to query tables outside my schema. EDIT My apologies for not providing as much information as possible the first time around. I was under the impression this question was more simple. I'm trying create a trigger on a table that changes some fields on a newly inserted row based on the existence of some data that may or may not be in a table that is in another schema. The user account that I'm using to create the trigger does have the permissions to run the queries independently. In fact, I've had my trigger print the query I'm trying to run and was able to run it on it's own successfully. I should also note that I'm building the query dynamically by using the EXECUTE IMMEDIATE statement. Here's an example: CREATE OR REPLACE TRIGGER MAIN_SCHEMA.EVENTS BEFORE INSERT ON MAIN_SCHEMA.EVENTS REFERENCING OLD AS OLD NEW AS NEW FOR EACH ROW DECLARE rtn_count NUMBER := 0; table_name VARCHAR2(17) := :NEW.SOME_FIELD; key_field VARCHAR2(20) := :NEW.ANOTHER_FIELD; BEGIN CASE WHEN (key_field = 'condition_a') THEN EXECUTE IMMEDIATE 'select count(*) from OTHER_SCHEMA_A.'||table_name||' where KEY_FIELD='''||key_field||'''' INTO rtn_count; WHEN (key_field = 'condition_b') THEN EXECUTE IMMEDIATE 'select count(*) from OTHER_SCHEMA_B.'||table_name||' where KEY_FIELD='''||key_field||'''' INTO rtn_count; WHEN (key_field = 'condition_c') THEN EXECUTE IMMEDIATE 'select count(*) from OTHER_SCHEMA_C.'||table_name||' where KEY_FIELD='''||key_field||'''' INTO rtn_count; END CASE; IF (rtn_count > 0) THEN -- change some fields that are to be inserted END IF; END; The trigger seams to fail on the EXECUTE IMMEDIATE with the previously mentioned error. EDIT I have done some more research and I can offer more clarification. The user account I'm using to create this trigger is not MAIN_SCHEMA or any one of the OTHER_SCHEMA_Xs. The account I'm using (ME) is given privileges to the involved tables via the schema users themselves. For example (USER_TAB_PRIVS): GRANTOR GRANTEE TABLE_SCHEMA TABLE_NAME PRIVILEGE GRANTABLE HIERARCHY MAIN_SCHEMA ME MAIN_SCHEMA EVENTS DELETE NO NO MAIN_SCHEMA ME MAIN_SCHEMA EVENTS INSERT NO NO MAIN_SCHEMA ME MAIN_SCHEMA EVENTS SELECT NO NO MAIN_SCHEMA ME MAIN_SCHEMA EVENTS UPDATE NO NO OTHER_SCHEMA_X ME OTHER_SCHEMA_X TARGET_TBL SELECT NO NO And I have the following system privileges (USER_SYS_PRIVS): USERNAME PRIVILEGE ADMIN_OPTION ME ALTER ANY TRIGGER NO ME CREATE ANY TRIGGER NO ME UNLIMITED TABLESPACE NO And this is what I found in the Oracle documentation: To create a trigger in another user's schema, or to reference a table in another schema from a trigger in your schema, you must have the CREATE ANY TRIGGER system privilege. With this privilege, the trigger can be created in any schema and can be associated with any user's table. In addition, the user creating the trigger must also have EXECUTE privilege on the referenced procedures, functions, or packages. Here: Oracle Doc So it looks to me like this should work, but I'm not sure about the "EXECUTE privilege" it's referring to in the doc.

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• SQL SERVER – Automation Process Good or Ugly

  - by pinaldave

  This blog post is written in response to T-SQL Tuesday hosted by SQL Server Insane Asylum. The idea of this post really caught my attention. Automation – something getting itself done after the initial programming, is my understanding of the subject. The very next thought was – is it good or evil? The reality is there is no right answer. However, what if we quickly note a few things, then I would like to request your help to complete this post. We will start with the positive parts in SQL Server where automation happens. The Good If I start thinking of SQL Server and Automation the very first thing that comes to my mind is SQL Agent, which runs various jobs. Once I configure any task or job, it runs fine (till something goes wrong!). Well, automation has its own advantages. We all have used SQL Agent for so many things – backup, various validation jobs, maintenance jobs and numerous other things. What other kinds of automation tasks do you run in your database server? The Ugly This part is very interesting, because it can get really ugly(!). During my career I have found so many bad automation agent jobs. Client had an agent job where he was dropping the clean buffers every hour Client using database mail to send regular emails instead of necessary alert related emails The best one – A client used new Missing Index and Unused Index scripts in SQL Agent Job to follow suggestions 100%. Believe me, I have never seen such a badly performing and hard to optimize database. (I ended up dropping all non-clustered indexes on the development server and ran production workload on the development server again, then configured with optimal indexes). Shrinking database is performance killer. It should never be automated. SQL SERVER – Shrinking Database is Bad – Increases Fragmentation – Reduces Performance The one I hate the most is AutoShrink Database. It has given me hard time in my career quite a few times. SQL SERVER – SHRINKDATABASE For Every Database in the SQL Server Automation is necessary but common sense is a must when creating automation. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology

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• SQL SERVER – Working with FileTables in SQL Server 2012 – Part 1 – Setting Up Environment

  - by pinaldave

  Filestream is a very interesting feature, and an enhancement of FileTable with Filestream is equally exciting. Today in this post, we will learn how to set up the FileTable Environment in SQL Server. The major advantage of FileTable is it has Windows API compatibility for file data stored within an SQL Server database. In simpler words, FileTables remove a barrier so that SQL Server can be used for the storage and management of unstructured data that are currently residing as files on file servers. Another advantage is that the Windows Application Compatibility for their existing Windows applications enables to see these data as files in the file system. This way, you can use SQL Server to access the data using T-SQL enhancements, and Windows can access the file using its applications. So for the first step, you will need to enable the Filestream feature at the database level in order to use the FileTable. -- Enable Filestream EXEC sp_configure filestream_access_level, 2 RECONFIGURE GO -- Create Database CREATE DATABASE FileTableDB ON PRIMARY (Name = FileTableDB, FILENAME = 'D:\FileTable\FTDB.mdf'), FILEGROUP FTFG CONTAINS FILESTREAM (NAME = FileTableFS, FILENAME='D:\FileTable\FS') LOG ON (Name = FileTableDBLog, FILENAME = 'D:\FileTable\FTDBLog.ldf') WITH FILESTREAM (NON_TRANSACTED_ACCESS = FULL, DIRECTORY_NAME = N'FileTableDB'); GO Now, you can run the following code and figure out if FileStream options are enabled at the database level. -- Check the Filestream Options SELECT DB_NAME(database_id), non_transacted_access, non_transacted_access_desc FROM sys.database_filestream_options; GO You can see the resultset of the above query which returns resultset as the following image shows. As you can see , the file level access is set to 2 (filestream enabled). Now let us create the filetable in the newly created database. -- Create FileTable Table USE FileTableDB GO CREATE TABLE FileTableTb AS FileTable WITH (FileTable_Directory = 'FileTableTb_Dir'); GO Now you can select data using a regular select table. SELECT * FROM FileTableTb GO It will return all the important columns which are related to the file. It will provide details like filesize, archived, file types etc. You can also see the FileTable in SQL Server Management Studio. Go to Databases >> Newly Created Database (FileTableDB) >> Expand Tables Here, you will see a new folder which says “FileTables”. When expanded, it gives the name of the newly created FileTableTb. You can right click on the newly created table and click on “Explore FileTable Directory”. This will open up the folder where the FileTable data will be stored. When you click on the option, it will open up the following folder in my local machine where the FileTable data will be stored: \\127.0.0.1\mssqlserver\FileTableDB\FileTableTb_Dir In tomorrow’s blog post as Part 2, we will go over two methods of inserting the data into this FileTable. Reference : Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: Filestream

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