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  • Creating a [materialised]view from generic data in Oracle/Mysql

    - by Andrew White
    I have a generic datamodel with 3 tables CREATE TABLE Properties ( propertyId int(11) NOT NULL AUTO_INCREMENT, name varchar(80) NOT NULL ) CREATE TABLE Customers ( customerId int(11) NOT NULL AUTO_INCREMENT, customerName varchar(80) NOT NULL ) CREATE TABLE PropertyValues ( propertyId int(11) NOT NULL, customerId int(11) NOT NULL, value varchar(80) NOT NULL ) INSERT INTO Properties VALUES (1, 'Age'); INSERT INTO Properties VALUES (2, 'Weight'); INSERT INTO Customers VALUES (1, 'Bob'); INSERT INTO Customers VALUES (2, 'Tom'); INSERT INTO PropertyValues VALUES (1, 1, '34'); INSERT INTO PropertyValues VALUES (2, 1, '80KG'); INSERT INTO PropertyValues VALUES (1, 2, '24'); INSERT INTO PropertyValues VALUES (2, 2, '53KG'); What I would like to do is create a view that has as columns all the ROWS in Properties and has as rows the entries in Customers. The column values are populated from PropertyValues. e.g. customerId Age Weight 1 34 80KG 2 24 53KG I'm thinking I need a stored procedure to do this and perhaps a materialised view (the entries in the table "Properties" change rarely). Any tips?

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  • Should I catch exceptions thrown when closing java.sql.Connection

    - by jb
    Connection.close() may throw SqlException, but I have always assumed that it is safe to ignore any such exceptions (and I have never seen code that does not ignore them). Normally I would write: try{ connection.close(); }catch(Exception e) {} Or try{ connection.close(); }catch(Exception e) { logger.log(e.getMessage(), e); } The question is: Is it bad practice (and has anyone had problems when ignoring such exeptions). When Connection.close() does throw any exception. If it is bad how should I handle the exception. Comment: I know that discarding exceptions is evil, but I'm reffering only to exceptions thrown when closing a connection (and as I've seen this is fairly common in this case). Does anyone know when Connection.close() may throw anything?

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  • Django: Grouping by Dates and Servers

    - by TheLizardKing
    So I am trying to emulate google app's status page: http://www.google.com/appsstatus#hl=en but for backups for our own servers. Instead of service names on the left it'll be server names but the dates and hopefully the pagination will be there too. My models look incredibly similar to this: from django.db import models STATUS_CHOICES = ( ('UN', 'Unknown'), ('NI', 'No Issue'), ('IS', 'Issue'), ('NR', 'Not Running'), ) class Server(models.Model): name = models.CharField(max_length=32) def __unicode__(self): return self.name class Backup(models.Model): server = models.ForeignKey(Server) created = models.DateField(auto_now_add=True) modified = models.DateTimeField(auto_now=True) status = models.CharField(max_length=2, choices=STATUS_CHOICES, default='UN') issue = models.TextField(blank=True) def __unicode__(self): return u'%s: %s' % (self.server, self.get_status_display()) My issue is that I am having a hell of a time displaying the information I need. Everyday a little after midnight a cron job will run and add a row for each server for that day, defaulting on status unknown (UN). My backups.html: {% extends "base.html" %} {% block content %} <table> <tr> <th>Name</th> {% for server in servers %} <th>{{ created }}</th> </tr> <tr> <td>{{ server.name }}</td> {% for backup in server.backup_set.all %} <td>{{ backup.get_status_display }}</td> {% endfor %} </tr> {% endfor %} </table> {% endblock content %} This actually works but I do not know how to get the dates to show. Obviously {{ created }} doesn't do anything but the servers don't have create dates. Backups do and because it's a cron job there should only be X number of rows with any particular date (depending on how many servers we are following for that day). Summary I want to create a table, X being server names, Y being dates starting at today while all the cells being the status of a backup. The above model and template should hopefully give you an idea what my thought process but I am willing to alter anything. Basically I am create a fancy excel spreadsheet.

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  • Copying Some from a PostgreSQL Server to Another

    - by whollychao
    I am in need of an application that can periodically transmit select rows from a PostgreSQL database across a network to a second PostgreSQL server. Typically these will be the most recent row added, pulled and transmitted every 10-30 seconds. The primary servers run in a MS Windows environment with a high-latency, and occasionally intermittent, network connection. Therefore, any application would have to be tolerant of this and ideally automatically reconnect / resend data that could not be transmitted. Due to the environment and the requirements, a full-blown replication package would be unnecessary. I appreciate any help anyone has with this problem.

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  • Varchar columns: Nullable or not.

    - by NYSystemsAnalyst
    The database development standards in our organization state the varchar fields should not allow null values. They should have a default value of an empty string (""). I know this makes querying and concatenation easier, but today, one of my coworkers questioned me about why that standard only existed for varchar types an not other datatypes (int, datetime, etc). I would like to know if others consider this to be a valid, defensible standard, or if varchar should be treated the same as fields of other data types? I believe this standard is valid for the following reason: I believe that an empty string and null values, though technically different, are conceptually the same. An empty, zero length string is a string that does not exist. It has no value. However, a numeric value of 0 is not the same as NULL. For example, if a field called OutstandingBalance has a value of 0, it means there are $0.00 remaining. However, if the same field is NULL, that means the value is unknown. On the other hand, a field called CustomerName with a value of "" is basically the same as a value of NULL because both represent the non-existence of the name. I read somewhere that an analogy for an empty string vs. NULL is that of a blank CD vs. no CD. However, I believe this to be a false analogy because a blank CD still phyically exists and still has physical data space that does not have any meaningful data written to it. Basically, I believe a blank CD is the equivalent of a string of blank spaces (" "), not an empty string. Therefore, I believe a string of blank spaces to be an actual value separate from NULL, but an empty string to be the absense of value conceptually equivalent to NULL. Please let me know if my beliefs regarding variable length strings are valid, or please enlighten me if they are not. I have read several blogs / arguments regarding this subject, but still do not see a true conceptual difference between NULLs and empty strings.

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  • COUNT(*) vs. COUNT(1) vs. COUNT(pk): which is better?

    - by zneak
    Hello guys, I often find these three variants: SELECT COUNT(*) FROM Foo; SELECT COUNT(1) FROM Foo; SELECT COUNT(PrimaryKey) FROM Foo; As far as I can see, they all do the same thing, and I find myself using the three in my codebase. However, I don't like to do the same thing different ways. To which one should I stick? Is any one of them better than the two others?

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  • How to get top 3 frequencies in MySQL?

    - by Amenhotep
    Hello, In MySQL I have a table called "meanings" with three columns: "person" (int), "word" (byte, 16 possible values) "meaning" (byte, 26 possible values). A person assigns one or more meanings to each word: person word meaning ------------------- 1 1 4 1 2 19 1 2 7 <-- second meaning for word 2 1 3 5 ... 1 16 2 Then another person, and so on. There will be thousands of persons. I need to find for each of the 16 words the top three meanings (with their frequencies). Something like: word 1: meaning 5 (35% of people), meaning 19 (22% of people), meaning 2 (13% of people) word 2: meaning 8 (57%), meaning 1 (18%), meaning 22 (7%) ... Is it possible to solve this with a single MySQL query? (If this problem is a classic one and has been answered elsewhere, I would appreciate if you could give me a link to the solution.) Thank you very much, ve

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  • Postgresql Altering Table

    - by Jahn
    Is it possible to alter a table to add a new column and make that column a foreign key to another table in a single command in Postgresql? "alter table x add column y id references z(id)" doesn't seem to work as I had hoped.

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  • how to insert record in database with each date of month on single button click ?

    - by Mr. Goo
    I have two textbox .... textbox1 and textbox2 textbox1 == choose from date textbox2 == choose to date if user select from date in textbox1 as 01-May-2011 and in textbox2 as 30-May-2011 then all the dates from 01-MAy-2011 to 30-May-2011 will be inserted in each row of mssql2005 datatable... example. . : IN database Table1 structure ... ID Date 1 01-MAy-2011 2 02-MAy-2011 3 03-MAy-2011 4 04-MAy-2011 5 05-MAy-2011 and so on till 30-May-2011

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  • Heterogeneous queries require the ANSI_NULLS

    - by Dezigo
    I wrote a trigger. USE [TEST] GO /****** Object: Trigger [dbo].[TR_POSTGRESQL_UPDATE_YC] Script Date: 05/26/2010 08:54:03 ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO ALTER TRIGGER [dbo].[TR_POSTGRESQL_UPDATE_YC] ON [dbo].[BCT_CNTR_EVENTS] FOR INSERT AS BEGIN DECLARE @MOVE_TIME varchar(14); DECLARE @MOVE_TIME_FORMATED varchar(20); DECLARE @RELEASE_NOTE varchar(32); DECLARE @CMR_NUMBER varchar(15); DECLARE @MOVE_TYPE varchar(2); SELECT @MOVE_TIME = inserted.move_time ,@MOVE_TYPE = inserted.move_type ,@RELEASE_NOTE = inserted.release_note ,@CMR_NUMBER = inserted.cmr_number FROM inserted IF(@MOVE_TYPE = 'YC') BEGIN SET @MOVE_TIME_FORMATED = SUBSTRING(@MOVE_TIME,1,4) + '-' + SUBSTRING(@MOVE_TIME,5,2) + '-' + SUBSTRING(@MOVE_TIME,7,2) + ' 00:00:00' --UPDATE OpenQuery(POSTGRESQL_SERV,'SELECT visit_cmr,visit_timestamp,visit_pin FROM VISIT') -- SET visit_cmr = @RELEASE_NOTE -- WHERE visit_timestamp = @MOVE_TIME_FORMATED -- AND visit_pin = right(@CMR_NUMBER,5) -- AND visit_cmr IS NULL END SET NOCOUNT ON; END When I have inserted a row,I have get an error **Heterogeneous queries require the ANSI_NULLS and ANSI_WARNINGS options to be set for the connection. This ensures consistent query semantics. Enable these options and then reissue your query.** Then I ofcourse SET SET ANSI_WARNINGS is ON but it`s not work for me. (trigger fo linked server postgresql) I have restarted a server. not work again.

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  • Building Stored Procedure to group data into ranges with roughly equal results in each bucket

    - by Len
    I am trying to build one procedure to take a large amount of data and create 5 range buckets to display the data. the buckets ranges will have to be set according to the results. Here is my existing SP GO /****** Object: StoredProcedure [dbo].[sp_GetRangeCounts] Script Date: 03/28/2010 19:50:45 ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO ALTER PROCEDURE [dbo].[sp_GetRangeCounts] @idMenu int AS declare @myMin decimal(19,2), @myMax decimal(19,2), @myDif decimal(19,2), @range1 decimal(19,2), @range2 decimal(19,2), @range3 decimal(19,2), @range4 decimal(19,2), @range5 decimal(19,2), @range6 decimal(19,2) SELECT @myMin=Min(modelpropvalue), @myMax=Max(modelpropvalue) FROM xmodelpropertyvalues where modelPropUnitDescriptionID=@idMenu set @myDif=(@myMax-@myMin)/5 set @range1=@myMin set @range2=@myMin+@myDif set @range3=@range2+@myDif set @range4=@range3+@myDif set @range5=@range4+@myDif set @range6=@range5+@myDif select @myMin,@myMax,@myDif,@range1,@range2,@range3,@range4,@range5,@range6 select t.range as myRange, count(*) as myCount from ( select case when modelpropvalue between @range1 and @range2 then 'range1' when modelpropvalue between @range2 and @range3 then 'range2' when modelpropvalue between @range3 and @range4 then 'range3' when modelpropvalue between @range4 and @range5 then 'range4' when modelpropvalue between @range5 and @range6 then 'range5' end as range from xmodelpropertyvalues where modelpropunitDescriptionID=@idmenu) t group by t.range order by t.range This calculates the min and max value from my table, works out the difference between the two and creates 5 buckets. The problem is that if there are a small amount of very high (or very low) values then the buckets will appear very distorted - as in these results... range1 2806 range2 296 range3 75 range5 1 Basically I want to rebuild the SP so it creates buckets with equal amounts of results in each. I have played around with some of the following approaches without quite nailing it... SELECT modelpropvalue, NTILE(5) OVER (ORDER BY modelpropvalue) FROM xmodelpropertyvalues - this creates a new column with either 1,2,3,4 or 5 in it ROW_NUMBER()OVER (ORDER BY modelpropvalue) between @range1 and @range2 ROW_NUMBER()OVER (ORDER BY modelpropvalue) between @range2 and @range3 or maybe i could allocate every record a row number then divide into ranges from this?

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  • How do I perform 'WHERE' on groups of rows?

    - by Drew
    I have a table, which looks like: +-----------+----------+ + person_id + group_id + +-----------+----------+ + 1 + 10 + + 1 + 20 + + 1 + 30 + + 2 + 10 + + 2 + 20 + + 3 + 10 + +-----------+----------+ I need a query such that only person_ids with groups 10 AND 20 AND 30 are returned (only person_id: 1). I am not sure how to do this, as from what I can see it would require me to group the rows by person_id and then select the rows which contain all group_ids. I'm looking for something which will preserve the use of keys without resorting to string operations on group_concat() or such.

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  • Linq2Sql Best Practices

    - by this. __curious_geek
    I'm recently migrating to Linq2Sql and all my future projects will be using Linq2Sql. Having said that, I researched a lot on how to properly plug-in Linq2Sql in application design. what to put at what layer ? How do you design your repositories and business layer services ? Should I use DTOs over Linq2Sql entities on interaction layer ? what things should I be careful about ? what problems did you face ? I did not find any rock-solid material that really talked about one single thing and everyone have their own opinions. I'm looking forward to your ideas on how to integrate/use Linq2Sql in projects. My priority is maintenance[it should be maintenable and when multiple people work on same project] and scalabilty [it should have scope of evolution]. Thanks.

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  • Adding a computed column to an ActiveRecord query

    - by bmwbzz
    Hi, I am running a query using a scope and some conditions. Something like this: conditions[:offset] = (options[:page].to_i - 1) * PAGE_SIZE unless options[:page].blank? conditions[:limit] = options[:limit] ||= PAGE_SIZE scope = Promo.enabled.active results = scope.all conditions I'd like to add a computed column to the query (at the point when I'm now calling scope.all). Something like this: (ACOS(least(1,COS(0.71106459055501)*COS(-1.2915436464758)*COS(RADIANS(addresses.lat))*COS(RADIANS(addresses.lng))+ COS(0.71106459055501)*SIN(-1.2915436464758)*COS(RADIANS(addresses.lat))*SIN(RADIANS(addresses.lng))+ SIN(0.71106459055501)*SIN(RADIANS(addresses.lat))))*3963.19) as accurate_distance Is there a way to do that without just using find_by_sql and rewriting the whole existing query? Thanks!

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  • Tool Compare the tables in two different databeses

    - by user191124
    I am using Toad. Frequently i need to compare tables in two different test environments. the tables present in them are same but the data differs. i just need to know what are the differences in the same tables which are in two different data bases.Are there any tools which can be installed on windows and use it to compare. Much appreciate your help:)

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  • LINQtoSQL: Query to return List<String>

    - by ctrlShiftBryan
    I have a LINQ query that returns some object like this... var query = from c in db.Customers where ... select c; Then I do this List<String> list = new List<String>(); foreach (ProgramLanguage c in query) { //GetUL returns a String list.Add(GetUL(c.Property,c.Property2)); } Is there a way to combine into something list this? var query = from c in db.Customers where ... select new { GetUL(c.Property,c.Property2) }).ToList<String>();

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  • Using application roles with DataReader

    - by Shahar
    I have an application that should use an application role from the database. I'm trying to make this work with queries that are actually run using Subsonic (2). To do this, I created my own DataProvider, which inherits from Subsonic's SqlDataProvider. It overrides the CreateConnection function, and calls sp_appsetrole to set the application role after the connection is created. This part works fine, and I'm able to get data using the application role. The problem comes when I try to unset the application role. I couldn't find any place in the code where my provider is called after the query is done, so I tried to add my own, by changing SubSonic code. The problem is that Subsonic uses a data reader. It loads data from the data reader, and then closes it. If I unset the application role before the data reader is closed, I get an error saying: There is already an open DataReader associated with this Command which must be closed first. If I unset the application role after the data reader is closed, I get an error saying ExecuteNonQuery requires an open and available Connection. The connection's current state is closed. I can't seem to find a way to close the data reader without closing the connection.

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  • How to ensure DB security for a Windows Forms application?

    - by Vilx-
    The basic setup is classic - you're creating a Windows Forms application that connects to a DB and does all kinds of enterprise-y stuff. Naturally, such an application will have many users with different access rights in the DB, and each with their own login name and password. So how do you implement this? One way is to create a DB login for every application user, but that's a pretty serious thing to do, which even requires admin rights on the DB server, etc. If the DB server hosts several applications, the admins are quite likely not to be happy with this. In the web world typically one creates his own "Users" table which contains all the necessary info, and uses one fixed DB login for all interaction. That is all nice for a web app, but a windows forms can't hide this master login information, negating security altogether. (It can try to hide, but all such attempts are easily broken with a bit of effort). So... is there some middle way? Perhaps logging in with a fixed login, and then elevating priviledges from a special stored procedure which checks the username and password?

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  • mysql subquery strangely slow

    - by aviv
    I have a query to select from another sub-query select. While the two queries look almost the same the second query (in this sample) runs much slower: SELECT user.id ,user.first_name -- user.* FROM user WHERE user.id IN (SELECT ref_id FROM education WHERE ref_type='user' AND education.institute_id='58' AND education.institute_type='1' ); This query takes 1.2s Explain on this query results: id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY user index first_name 152 141192 Using where; Using index 2 DEPENDENT SUBQUERY education index_subquery ref_type,ref_id,institute_id,institute_type,ref_type_2 ref_id 4 func 1 Using where The second query: SELECT -- user.id -- user.first_name user.* FROM user WHERE user.id IN (SELECT ref_id FROM education WHERE ref_type='user' AND education.institute_id='58' AND education.institute_type='1' ); Takes 45sec to run, with explain: id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY user ALL 141192 Using where 2 DEPENDENT SUBQUERY education index_subquery ref_type,ref_id,institute_id,institute_type,ref_type_2 ref_id 4 func 1 Using where Why is it slower if i query only by index fields? Why both queries scans the full length of the user table? Any ideas how to improve? Thanks.

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  • Put logic behind generated LinqToSql fields

    - by boris callens
    In a database I use throughout several projects, there is a field that should actually be a boolean but is for reasons nobody can explain to me a field duplicated over two tables where one time it is a char ('Y'/'N') and one time an int (1/0). When I generate a datacontext with LinqToSql the fields off course gets these datatypes. It would be nice if I don't have to drag this stupid choice of datatype throughout the rest of my application. Is there a way to give the generated classes a little bit of logic that just return me return this.equals('Y'); and return this==1; Preferably without having to make an EXTRA field in my partial class. It would be a solution to give the generated field a totally different name that can only be accessed through the partial class and then generate the extra field with the original name with my custom logic in the partial class. I don't know how to alter the accesibility level in my generated class though.. Any suggestions?

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