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  • How best can I extract a logical model from a physical DB model

    - by Dean
    We have made substantial changes to our physical DB, now as it is the ne dof the project I would like to abstract a logical model from this, to allow me to generate schemas for both Oracle and SQL Server. Can anyone guide me as to the best way to achieve this. I was hoping TOAD data modeller would help but I can't seem to see any options to do what I require?

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  • Composite Primary and Cardinality

    - by srini.venigalla
    I have some questions on Composite Primary Keys and the cardinality of the columns. I searched the web, but did not find any definitive answer, so I am trying again. The questions are: Context: Large (50M - 500M rows) OLAP Prep tables, not NOSQL, not Columnar. MySQL and DB2 1) Does the order of keys in a PK matter? 2) If the cardinality of the columns varies heavily, which should be used first. For example, if I have CLIENT/CAMPAIGN/PROGRAM where CLIENT is highly cardinal, CAMPAIGN is moderate, PROGRAM is almost like a bitmap index, what order is the best? 3) What order is the best for Join, if there is a Where clause and when there is no Where Clause (for views) Thanks in advance.

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  • need help with db-query on sql-server 2005.

    - by Avinash
    We're seeing strange behavior when running two versions of a query on SQL Server 2005: version A: SELECT otherattributes.* FROM listcontacts JOIN otherattributes ON listcontacts.contactId = otherattributes.contactId WHERE listcontacts.listid = 1234 ORDER BY name ASC version B: DECLARE @Id AS INT; SET @Id = 1234; SELECT otherattributes.* FROM listcontacts JOIN otherattributes ON listcontacts.contactId = otherattributes.contactId WHERE listcontacts.listid = @Id ORDER BY name ASC Both queries return 1000 rows; version A takes on average 15s; version B on average takes 4s. Could anyone help us understand the difference in execution times of these two versions of SQL? If we invoke this query via named parameters using NHibernate, we see the following query via SQL Server profiler: EXEC sp_executesql N'SELECT otherattributes.* FROM listcontacts JOIN otherattributes ON listcontacts.contactId = otherattributes.contactId WHERE listcontacts.listid = @id ORDER BY name ASC', N'@id INT', @id=1234; ...and this tends to perform as badly as version A. Thanks in advance,

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  • Creating a Group of Groups in Django

    - by Greg
    I'm creating my own Group model; I'm not referring to the builtin Group model. I want each hroup to be a member of another group (it's parent), but there is the one "top" group that doesn't have a parent group. The admin interface won't let me create a group without entering a parent. I get the error personnel_group.parent_id may not be NULL. My Group model looks like this: class Group(models.Model): name = models.CharField(max_length=50) parent = models.ForeignKey('self', blank=True, null=True) order = models.IntegerField() icon = models.ImageField(upload_to='groups', blank=True, null=True) description = models.TextField(blank=True, null=True) How can I accomplish this? Thanks.

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  • SQLServer using too much memory

    - by Israel Pereira Valverde
    I have installed on my desktop machine (with windows 7) SQLServer 2008 R2 Express. I have only one local server running (./SQLEXPRESS) but the sqlserver process is taking ALL the RAM possible. With an machine with 3GB of RAM the things starts to get slow, so I limited the maximun amount of RAM in the server, and now, constantly the SQLServer give some error messages that the memory is not enought. It's using 1GB of RAM with only one LOCAL server with 2 databases completely empty, how 1GB of RAM isn't enought ? When the process start it's using an really acceptable amount of memory (around 80MB) but it's keep increasing until it reaches the maximun defined and start to complain about having not enought memory available. In that point I have to restart the server to use it again. I have read about an hotfix to solve one of the errors I got from sqlserver: There is insufficient system memory in resource pool 'internal' to run this query But it's already installed on my sqlserver. Why it's using so much memory?

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  • Copy VSS structure to server with asp.net

    - by Tyzak
    i want to copy the structure (with the documents) from our vss server to an webserver. Therefore i want to create an application which is on this webserver. i want to use asp.net. i don't know what exactly i need therefore : I have to build somekind of connection? then go throw the structure and copy it somehow : ? important: i want to copy the documents with the right creation date ( it changes when i just copy the doc.) are there APIs for asp.net <- vss?

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  • capturing user IP address information for audit

    - by Samuel
    We have a requirement to log IP address information of all users who use a certain web application based on JEE 5. What would be an appropriate sql data type for storing IPv4 or IPv6 addressses in the following supported databases (h2, mysql, oracle). There is also a need to filter activity from certain IP addresses. Should I just treat the representation as a string field (say varchar(32) to hold ipv4, ipv6 addresses)

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  • When to use SQL Table Alias

    - by Rossini
    I curious to know how people are using table alias. The other developers where I work always use table alias, and always use the alias of a, b, c, ect. Here's an example SELECT a.TripNum, b.SegmentNum, b.StopNum, b.ArrivalTime FROM Trip a, Segment b WHERE a.TripNum = b.TripNum I disagree with them, and think table alias should be use more sparingly. I think it should be used when including the same table twice in a query, or when the table name is very long and using a shorter name in the query will make the query easier to read. I also think the alias should be a good name instead of a letter. In the above example if I felt I needed to use 1 letter table alias I would use t for the Trip table and s for the segment table.

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  • I have created a PHP script and I am lacking to extract the primary key, I have given flow below, pl

    - by Parth
    I am using MySQL DB, working for Joomla, My requirement is tracking the activity like insert/update/delete on any table and store it in another audit table using triggers, i.e. I am doing Auditing. DB's table structure: Few tables dont have any PK nor auto increment key Flow of my script is : I fetch out all table from DB. I check whether the table have any trigger or not. If yes then it moves to check nfor next table and so on. If it does'nt find any trigger then it creates the triggers for the table, such that, -it first checks if the table has any primary key or not(for inserting in Tracking audit table for every change made) if it has the primary key then it uses it further in creation of trigger. if it doesnt find any PK then it proceeds further in creating the trigger without inserting any id in audit table Now here, My problem is I need the PK every time so that I can record the id of any particular table in which the insert/update/delete is performed, so that further i can use this audit track table to replicate in production DB.. Now as I haave mentioned earlier that I am not available with PK/auto-incremented in some table, then what should I do get the particular id in which change is done? please guide me...GEEKS!!!

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  • Mysql random rows

    - by n00b
    please read the whole question... 90% of you dont seem to do that and some of you only read the title obviously... and if you dont know the solution, dont answer - i wont have to downvote you -.-'' im entertaining the idea of getting random rows directly from mysql. what i found was SELECT * FROM tablename WHERE somefield='something' ORDER BY RAND() LIMIT 5 but even i see how slow that would be.. is the only way to do this doing something like SELECT * FROM tablename WHERE somefield='something' LIMIT RAND(aincrementvalue-5), 1 5 times? or is there a way that i with my little knowlege of databases cant come up with ? (no i dont want random indexes. i hate the idea of them...) @commenters - please first look, then think, then look again, think again and then post. i wont point fingers but i dislike stupid comments and why i think random indexes are a nasty hack ? it doesnt give you random results. it gives you x results from a random index in a predefined order its like a gapless id only in the wrong order if you fetch by 1 row and get true randomness you fall back to my method but with an additional junk field finally the reason the field exists is only to serve as a helper to something that can be done without it with almost same performance (but the quality (randomness) is better), so it is a nasty hack ;) i solved it, look @ my answer... if you think its incorrect please tell me :)

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  • How to use multiple database in a PHP web application?

    - by Harish
    I am making a PHP web Application in which i am using MySQL as database server, i want to make backup of some tables from one database to another database(with that tables in it). i have created two different connection, but the table is not updated. $dbcon1 = mysql_connect(DB_SERVER,DB_USER,DB_PASSWORD) or die(mysql_error()); $dbase1 = mysql_select_db(TEMP_DB_NAME,$dbcon)or die(mysql_error()); $query1=mysql_query("SELECT * FROM emp"); while($row = mysql_fetch_array($query1, MYSQL_NUM)) { $dbcon2 = mysql_connect(DB_SERVER,DB_USER,DB_PASSWORD) or die(mysql_error()); $dbase2 = mysql_select_db(TEMP_DB_NAME2,$dbcon)or die(mysql_error()); mysql_query("INSERT INTO backup_emp VALUES(null,'$row[1]',$row[2])"); mysql_close($dbcon2); } the code above is taking the data of emp from first database, and updataing it into another backup_emp table of another database. the code is not working properly, is there any other way of doing this...please help.

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  • filter duplicates in SQL join

    - by Will
    When using a SQL join, is it possible to keep only rows that have a single row for the left table? For example: select * from A, B where A.id = B.a_id; a1 b1 a2 b1 a2 b2 In this case, I want to remove all except the first row, where a single row from A matched exactly 1 row from B. I'm using MySQL.

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  • MongoMapper: how do I create a model like this

    - by Vladimir R
    Suppose we have two models, Task and User. So a user can have many tasks and tasks should be able to have many users too. But, a task should also have a unique creator who is also a user. Exemple: A task in this context is like this: Task ID, Task Creator, Users who should do the task User_1 creates a task and he is then the creator. User_1 specifies User_2 and User_3 as users who should do the task. So these two last users are not creators of task. How do I create this models so that if I have a task object, I can find it's creator and users who should complete it. And how do I do, if I have a user, to find all tasks he created and all tasks he should complete. Thank you.

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  • Rails - Scalable calculation model

    - by H O
    I currently have a calculation structure in my rails app that has models metric, operand and operation_type. Presently, the metric model has many operands, and can perform calculations based on the operation_type (e.g. sum, multiply, etc.), and each operand is defined as being right or left (i.e. so that if the operation is division, the numerator and denominator can be identified). Presently, an operand is always an attribute of some model, e.g. @customer.sales.selling_price.sum. In order to make this scalable, in need to allow an operand to be either an attribute of some kind, or the results of a previous operation, i.e. an operand can be a metric. I have included a diagram of how my models currently look: Can anyone assist me with the most elegant way of allowing an operand to be an actual operand, or another metric? Thanks! EDIT: It seems based on the only answer so far that perhaps polymorphic associations are the way to go on this, but the answer is so brief I have no idea how they could be used in this way - can anyone elaborate? EDIT 2: OK, I think I'm getting somewhere - essentially i presently have a metric, which has_many operands, and an operand has_many metrics. I need a polymorphic self join, where a metric can also have many metrics - do I need to call this something else, perhaps calculated_metrics, so that the metric model can use itself? That would leave me with a situation where a metric has_many operands, and a metric has many calculated_metrics.

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  • Decimal rounding strategies in enterprise applications

    - by Sapphire
    Well, I am wondering about a thing with rounding decimals, and storing them in DB. Problem is like this: Let's say we have a customer and a invoice. The invoice has total price of $100.495 (due to some discount percentage which is not integer number), but it is shown as $100.50 (when rounded, just for print on invoice). It is stored in the DB with the price of $100.495, which means that when customer makes a deposit of $100.50 it will have $0.005 extra on the account. If this is rounded, it will appear as $0, but after couple of invoices it would keep accumulating, which would appear wrong (although it actually is not). What is best to do in this case. Store the value of $100.50, or leave everything as-is?

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  • large databases in sqlite - file size considerations?

    - by Gj
    I'm using a sqlite db which is very convenient and seems to meet all of my needs at this point. Currently my db size is <50MB, but I now need to add a new table which will store large text blobs, which will cause the db to reach up to 5GB within the next year. Would sqlite be able to deal with a 5GB db size? Any caveats to that, compared with say mysql?

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  • True or False: Good design calls for every table to have a primary key, if nothing else, a running i

    - by Velika
    Consider a grocery store scenario (I'm making this up) where you have FACT records that represent a sale transaction, where the columns of the Fact table include SaleItemFact Table ------------------ CustomerID ProductID Price DistributorID DateOfSale Etc Etc Etc Even if there are duplicates in the table when you consider ALL the keys, I would contend that a surrogate running numeric key (i.e. identity column) should be made up, e.g., TransactionNumber of type Integer. I can see someone arguing that a Fact table might not have a unique key (though I'd invent one and waste the 4 bytes, but how about a dimension table?

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  • Why are there so many DB management Systems ?

    - by mr.bio
    Hi there , i always asked myself. Why are there so many DB management systems? I am not an DB expert and i never thought about using another DB than mysql. Programming languages offer different paradigms, so there it makes sense to choose a specific language for your purpose. What are factors to choose a specific DB management system ?

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  • Oracle : How can i find the holiday in a business day?

    - by Rajesh Kumar G
    Hi, Consider there are 3 different centers across the country,which have their different holidays schedule.Now i want to find that the current date is the business day or not(eliminate saturaday ,sunday and Holidays). tell me,Which one is feasible? Can i store the details of the holiday with description in 3 separate tables for 3 different centers or in a 3 separate file? is it possible to read the file using PL\SQl?

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  • Setting 0/1-to-1 relationship in SQLAlchemy?

    - by Timmy
    is there a proper way of setting up a 0/1-to-1 relationship? i want to be able to check if the related item exists without creating it: if item.relationship is None: item.relationship = item2() but it creates the insert statements on the if statement

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  • C# Find out what column caused the Sql Exception

    - by PaN1C_Showt1Me
    Hi. I'm getting an exception from SQL Data Reader (MS SQL as datastore) and I'd like to know which column name causes this Exception to be thrown. But I cannot find it in the InnerException.. nowhere. ((System.InvalidOperationException)ex.InnerException).StackTrace: System.Data.SqlClient.SqlDataReader.ReadColumnHeader(Int32 i) System.Data.SqlClient.SqlDataReader.IsDBNull(Int32 i) ... Where is it hidden please ?

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  • Using jQuery to store basic text string in mySQL base?

    - by Kenny Bones
    Could someone point me in the right direction here? Basically, I've got this jQuery code snippet: $('.bggallery_images').click(function () { var newBG = "url('" + $(this).attr('src'); var fullpath = $(this).attr('src'); var filename = fullpath.replace('img/Bakgrunner/', ''); $('#wrapper').css('background-image', newBG); // Lagre til SQL $.ajax({ url: "save_to_db.php", // The url to your function to handle saving to the db data: filename, dataType: 'Text', type: 'POST', // Could also use GET if you prefer success: function (data) { // Just for testing purposes. alert('Background changed to: ' + data); } }); }); This is being run when I click a certain button. So it's actually within a click handler. If I understand this correctly, this snippet takes the source if the image I just clicked and strips it so I end up with only the filename. If I do an alert(filename), I get the filename only. So this is working ok. But then, it does an ajax call to a php file called "save_to_db.php" and sends data: filename. This is correct right? Then, it does a callback which does an alert + data. Does this seem correct so far? Cause my php file looks like this: <?php require("dbconnect2.php"); $uploadstring = $_POST['filename']; $sessionid = $_SESSION['id']; echo ($sessionid); mysql_query("UPDATE brukere SET brukerBakgrunn = '$uploadstring' WHERE brukerID=" .$_SESSION['id']); mysql_close(); ?> When I click the image, the jQuery snippet fires and I get the results of this php file as output for the alert box. I think that the variables somehow are empty. Because notice the echo($sessionid); which is a variable I've created just to test what the session ID is. And it returns nothing. What could be the issue here? Edit: I just tried to echo out the $uploadstring variable as well and it also returns nothing. It's like the jQuery snippet doesn't even pass the variable on to the php file?

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