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  • Survey Data Model - How to avoid EAV and excessive denormalization?

    - by AlexDPC
    Hi everyone, My database skills are mediocre at best and I have to design a data model for survey data. I have spent some thoughts on this and right now I feel that I am stuck between some kind of EAV model and a design involving hundreds of tables, each with hundreds of columns (and thousands of records). There must be a better way to do this and I hope that the wise folks on this forum can help me. I have already searched various forums, but I couldn't really find a solution. If it has already been given elsewhere, please excuse me and provide me with a link so I can read it up. Some assumptions about the data I have to deal with: Each survey consists of 1 to n questionnaires Each questionnaire consists of 100-2,000 questions (please ignore that 2,000 questions really sound like a lot to answer...) Questions can be of various types: multiple-choice, free text, a number (like age, income, percentages, ...) Each survey involves 10-200 countries (These are not the respondents. The respondents are actually people in the countries.) Depending on the type of questionnaire, each questionnaire is answered by 100-20,000 respondents per country. A country can adapt the questionnaires for a survey, i.e. add, remove or edit questions The data for one country is gathered in a separate database in that country. There is no possibility for online integration from the start. The data for all countries has to be integrated later. This means for example, if a country has deleted a question, that data must somehow be derived from what they sent in order to achieve a uniform design across all countries I will have to write the integration and cleaning software, which will need to work with every country's data In the end the data needs to be exported to flat files, one rectangular grid per country and questionnaire. I have already discussed this topic with people from various backgrounds and have not come to a good solution yet. I mainly got two kinds of opinions. The domain experts, who are used to working with flat files (spreadsheet-style) for data processing and analysis vote for a denormalized structure with loads of tables and columns as I described above (1 table per country and questionnaire). This sounds terrible to me, because I learned that wide tables are to be avoided, it will be annoying to determine which columns are actually in a table when working with it, the database will become cluttered with hundreds of tables (or I even need to set up multiple databases, each with a similar yet a bit differetn design), etc. O-O-programmers vote for a strongly "normalized" design, which would effectively lead to a central table containing all the answers from all respondents to all questions. This table would either need to contain a column of type sql_variant type or multiple answer columns with different types to store answers of different types (multiple choice, free text, ..). The former would essentially be a EAV model. I tend to follow Joe Celko here, who strongly discourages its use (he calls it OTLT or "One True Lookup Table"). The latter would imply that each row would contain null cells for the not applicable types by design. Another alternative I could think of would be to create one table per answer type, i.e., one for multiple-choice questions, one for free text questions, etc.. That's not so generic, it would lead to a lot of union joins, I think and I would have to add a table if a new answer type is invented. Sorry for boring you with all this text and thank you for your input! Cheers, Alex PS: I asked the same question here: http://www.eggheadcafe.com/community/aspnet/13/10242616/survey-data-model--how-to-avoid-eav-and-excessive-denormalization.aspx

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  • IS NULL doesn't work as expected in MSSQL 2000 with no Service Pack on it

    - by user306825
    The following batch executed on different instances of mssql 2000 illustrates the problem. select @@version create table a (a int) create table b (b int) insert into a(a) values (1) insert into a(a) values (2) insert into a(a) values (3) insert into b(b) values (1) insert into b(b) values (2) select * from a left outer join (select 1 as test, b from b) as j on j.b = a.a where j.test IS NULL drop table a drop table b Output 1: Microsoft SQL Server 2000 - 8.00.194 (Intel X86) Aug 6 2000 00:57:48 Copyright (c) 1988-2000 Microsoft Corporation Developer Edition on Windows NT 6.1 (Build 7600: ) (1 row(s) affected) (1 row(s) affected) (1 row(s) affected) (1 row(s) affected) (1 row(s) affected) (1 row(s) affected) a test b (0 row(s) affected) Output 2: Microsoft SQL Server 2000 - 8.00.2039 (Intel X86) May 3 2005 23:18:38 Copyright (c) 1988-2003 Microsoft Corporation Developer Edition on Windows NT 5.2 (Build 3790: Service Pack 2) (1 row(s) affected) (1 row(s) affected) (1 row(s) affected) (1 row(s) affected) (1 row(s) affected) (1 row(s) affected) a test b 3 NULL NULL (1 row(s) affected) If someone encounters the same problem - make sure you have the SP installed!

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  • Using Ruby on Rails, can a polymorphic database be created in a few steps (with polymorphic associat

    - by Jian Lin
    I thought it could be created in a few steps but it can't yet: rails poly cd poly ruby script/generate scaffold animal name:string obj_type:string obj_id:integer rake:migrate ruby script/generate scaffold human name:string passportNumber:string rake:migrate ruby script/generate scaffold dog name:string registrationNumber:string rake:migrate and now change app/models/animal.rb to: class Animal < ActiveRecord::Base belongs_to :obj, :polymorphic => true end and run ruby script/server and go to http://localhost:3000 I thought on the server then if I create an Michael, Human, J123456 and then Woofie, Dog, L23456 then the database will have entries in the Dogs table and "Humen" or "Humans" table as well as in the Animals table? But only the Animals table has records, Dogs and "Humen" do not for some reason. Is there some steps missing?

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  • Saving auto increment in MySQL

    - by oshafran
    Hello, I am trying to sync between 2 tables: I have active table where has auto_increment, and I have archive table with the same values. I would like both ID's to be unique (between the tables as well) - I mean, I would like to save auto incremenet, and if I UNION both table I still have uniqness. How can I do that? Is there a possibility to save auto increment when mysql is off?

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  • Oracle/c#: How do i use bind variables with select statements to return multiple records?

    - by twiga
    I have a question regarding Oracle bind variables and select statements. What I would like to achieve is do a select on a number different values for the primary key. I would like to pass these values via an array using bind values. select * from tb_customers where cust_id = :1 int[] cust_id = { 11, 23, 31, 44 , 51 }; I then bind a DataReader to get the values into a table. The problem is that the resulting table only contains a single record (for cust_id=51). Thus it seems that each statement is executed independently (as it should), but I would like the results to be available as a collective (single table). A workaround is to create a temporary table, insert all the values of cust_id and then do a join against tb_customers. The problem with this approach is that I would require temporary tables for every different type of primary key, as I would like to use this against a number of tables (some even have combined primary keys). Is there anything I am missing?

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  • creation of multiple dataset in Reporting service report

    - by brijit
    Hi, I have a SSRS report and using PL/SQL for the dataset creation. My report needs two tables 1 one gives detailed view.(dataset 1) 2 one below that gives a summary table (data should come from the calculations based on the data in 1 table) I am using a temporary table for the dataset one. What are the methods to get calculated result for dataset 2. I wrote 2 procedures for each. since first table is a temporary one i am not getting result for second dataset. Wht can be the options. Can I have multiple dataset outof single procedure please give me and idea. Thanks brijit

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  • Remove newlines and spaces

    - by Cosmin
    How can I remove newline between <table> .... </table> and add \n after each ex: <table border="0" cellspacing="0" cellpadding="0" width="450" class="descriptiontable"><tr> <td width="50%" valign="top"> <span class="displayb">Model Procesor:</span> Intel Celeron<br><span class="displayb">Frecventa procesor (MHz):</span> 2660<br><span class="displayb">Placa Video:</span> Intel Extreme Graphics 2<br><span class="displayb">Retea integrata:</span> 10/100Mbps, RJ-45<br><span class="displayb">Chipset:</span> Intel 845G<br> </td> <td width="50%" valign="top"> <span class="displayb">Capacitate RAM (MB):</span> 512<br><span class="displayb">Tip RAM:</span> DDR<br> </td> </tr></table> and become : <table border="0" cellspacing="0" cellpadding="0" width="450" class="descriptiontable"><tr><td width="50%" valign="top"><span class="displayb">Model Procesor:</span> Intel Celeron<br><span class="displayb">Frecventa procesor (MHz):</span> 2660<br><span class="displayb">Placa Video:</span> Intel Extreme Graphics 2<br><span class="displayb">Retea integrata:</span> 10/100Mbps, RJ-45<br><span class="displayb">Chipset:</span> Intel 845G<br></td><td width="50%" valign="top"><span class="displayb">Capacitate RAM (MB):</span> 512<br><span class="displayb">Tip RAM:</span> DDR<br></td></tr></table>\n s.

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  • "Special case" records for foreign key constraints

    - by keithjgrant
    Let's say I have a mysql table, called foo with a foreign key option_id constrained to the option table. When I create a foo record, the user may or may not have selected an option, and 'no option' is a viable selection. What is the best way to differentiate between 'null' (i.e. the user hasn't made a selection yet) and 'no option' (i.e. the user selected 'no option')? Right now, my plan is to insert a special record into the option table. Let's say that winds up with an id of 227 (this table already has a number of records at this point, so '1' isn't available). I have no need to access this record at a database level, and it would act as nothing more than a placeholder that the foreign key in the foo table can reference. So do I just hard-code '227' in my codebase when I'm creating 'foo' records where the user has selected 'no option'? The hard-coded id seems sloppy, and leaves room for error as the code is maintained down the road, but I'm not really sure of another approach.

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  • SQLAlchemy: a better way for update with declarative?

    - by hadrien
    I am a SQLAlchemy noob. Let's say I have an user table in declarative mode: class User(Base): __tablename__ = 'user' id = Column(u'id', Integer(), primary_key=True) name = Column(u'name', String(50)) When I know user's id without object loaded into session, I update such user like this: ex = update(User.__table__).where(User.id==123).values(name=u"Bob Marley") Session.execute(ex) I dislike using User.__table__, should I stop worrying with that? Is there a better way to do this? Thanx!

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  • sql insert query needed

    - by masfenix
    Hey guys, so I have two tables. They are pictured below. I have a master table "all_reports". And a user table "user list". The master table may have users that do not exist in the user list. I need to add them to the user list. The master table may have duplicates in them (check picture). The master list does not contain all the information that the user list requires (no manager, no HR status, no department.. again check picture).

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  • MySQL won't use index for query?

    - by Jack Sleight
    I have this table: CREATE TABLE `point` ( `id` INT(11) NOT NULL AUTO_INCREMENT, `siteid` INT(11) NOT NULL, `lft` INT(11) DEFAULT NULL, `rgt` INT(11) DEFAULT NULL, `level` SMALLINT(6) DEFAULT NULL, PRIMARY KEY (`id`), KEY `point_siteid_site_id` (`siteid`), CONSTRAINT `point_siteid_site_id` FOREIGN KEY (`siteid`) REFERENCES `site` (`id`) ON DELETE CASCADE ) ENGINE=INNODB AUTO_INCREMENT=35 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci And this query: SELECT * FROM `point` WHERE siteid = 1; Which results in this EXPLAIN information: +----+-------------+-------+------+----------------------+------+---------+------+------+-------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+-------+------+----------------------+------+---------+------+------+-------------+ | 1 | SIMPLE | point | ALL | point_siteid_site_id | NULL | NULL | NULL | 6 | Using where | +----+-------------+-------+------+----------------------+------+---------+------+------+-------------+ Question is, why isn't the query using the point_siteid_site_id index?

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  • Exporting de-aggregated data

    - by Ben
    I'm currently working on a data export feature for a survey application. We are using SQL2k8. We store data in a normalized format: QuestionId, RespondentId, Answer. We have a couple other tables that define what the question text is for the QuestionId and demographics for the RespondentId... Currently I'm using some dynamic SQL to generate a pivot that joins the question table to the answer table and creates an export, its working... The problem is that it seems slow and we don't have that much data (less than 50k respondents). Right now I'm thinking "why am I 'paying' to de-aggregate the data for each query? Why don't I cache that?" The data being exported is based on dynamic criteria. It could be "give me respondents that completed on x date (or range)" or "people that like blue", etc. Because of that, I think I have to cache at the respondent level, find out what respondents are being exported and then select their combined cached de-aggregated data. To me the quick and dirty fix is a totally flat table, RespondentId, Question1, Question2, etc. The problem is, we have multiple clients and that doesn't scale AND I don't want to have to maintain the flattened table as the survey changes. So I'm thinking about putting an XML column on the respondent table and caching the results of a SELECT * FROM Data FOR XML AUTO WHERE RespondentId = x. With that in place, I would then be able to get my export with filtering and XML calls into the XML column. What are you doing to export aggregated data in a flattened format (CSV, Excel, etc)? Does this approach seem ok? I worry about the cost of XML functions on larger result sets (think SELECT RespondentId, XmlCol.value('//data/question_1', 'nvarchar(50)') AS [Why is there air?], XmlCol.RinseAndRepeat)... Is there a better technology/approach for this? Thanks!

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  • MySQL Need some help with a query

    - by Jules
    I'm trying to fix some data by adding a new field. I have a backup from a few months ago and I have restored this database to my server. I'm looking at table called pads, its primary key is PadID and the field of importance is called RemoveMeDate. In my restored (older) database there is less records with an actual date set in RemoveMeDate. My control date is 2001-01-01 00:00:00 meaning that the record is not hidden aka visible. What I need to do is select all the records from the older database / table with the control date and join with those from the newer db /table where the control date is not set. I hope I've explained that correctly. I'll try again, with numbers. I have 80,000 visible records in the older table (with control date set) and 30,000 in the newer db/table. I need to select the 50,000 from the old database, to perform an update query. Heres my query, which I'd can't get to work as I'd like. jules-fix-reasons is the old database, jules is the newer one. select p.padid from `jules-fix-reasons`.`pads` p JOIN `jules`.`pads` ON p.padid = `jules`.`pads`.`PadID` where p.RemoveMeDate <> '2001-01-01 00:00:00' AND `jules`.`pads`.RemoveMeDate = '2001-01-01 00:00:00'

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  • User settings mechanism for Yii

    - by Peterim
    Hi guys! I need some help with user settings mechanism for my Yii-based application. I've created the following db structure to store user settings: table user with the following fields id | username | email | etc. table settingslist (to store a list of all possible settings with descriptions) with the following fields id | code | name | description table settings (to store all user settings) with the following fields id | userid | settingslistcode | value Now I'm stuck with the form which allows user to change his settings. I had to deal before with the regular models (i.e. for posts, comments, etc.) where every new model had only one row in the database (Post model - id | title | body |) with the certain amount of attributes (fields of the table). But now I need to store user settings in 10-15 rows and I don't know how to apply Yii model mechanism to work with this, so I can retrieve those settings in a single form (so user could change his preferences). Any suggestions are greatly appreciated. Thank you!

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  • Data retrieval and Join operations with cluster db server

    - by Goerge
    If any database spreads across multiple servers (ex. Microsoft Sql Server), how can we do join or filter operations. In my scenario, if suppose: A single table spreads across multiple servers how can we filter rows based on user input? If master table is there on one db server and transaction table is at another db server, how can we do join operations? Please let me know how can we achieve this and where can I get more details about this?

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  • Create Chart using PHP-MySQL

    - by Ajith
    I have a mysql table - request_events with three fields; request_eventsid,datetime,type.this table will track all the activities of my website day wise and also type wise.thus,type may be 1 or 2.I need to display an open-chart for understanding the progress.So I need to retrieve the ratio of type2/type1 as input day wise.How can I get all these input for last 30 days from this table.Please give me some idea....It already kill my week end.Please help me

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  • Implementation of MVC with SQLite and NSURLConnection, use cases?

    - by user324723
    I'm interested in knowing how others have implemented/designed database & web services in their iphone app and how they simplified it for the entire application. My application is dependent on these services and I can't figure out a efficient way to use them together due to the (semi)complexity of my requirements. My past attempts on combining them haven't been completely successful or at least optimal in my mind. I'm building a database driven iphone app that uses a relational database in sqlite and consumes web services based on missing content or user interaction. Like this hasn't been done before...right? Since I am using a relational database - any web services consumed requires normalization, parsing the result and persisting it to the database before it can be displayed in a table view controller. The applications UI consists of nested(nav controller) table views where a user can select a cell and be taken to the next table view where it attempts to populate the table views data source from the database. If nothing exists in the database then it will send a request via web services to download its content, thus download - parse - persist - query - display. Since the user has the ability to request a refresh of this data it still requires the same process. Quickly describing what I've implemented and tried to run with - 1st attempt - Used a singleton web service class that handled sending web service requests, parsing the result and returning it to the table view controller via delegate protocols. Once the controller received that data it would then be responsible for persisting it to the database and re-returning the result. I didn't like the idea of only preventing the case where the app delegate selector doesn't exists(released) causing the app to crash. 2nd attempt - Used NSNotificationCenter for easy access to both database and web services but later realized it was more complex due to adding and removing observers per view(which isn't advised anyways).

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  • Google Visualization Annotated Time Line, removing data points.

    - by Vitaly Babiy
    I am trying to build a graph that will change resolution depending on how far you are zoomed in. Here is what it looks like when you are complete zoomed out. So this looks good so when I zoom in I get a higher resolution data and my graph looks like this: The problem is when I zoom out the higher resolution data does not get cleared out of the graph: The tables below the graphs are table display what is in the DataTable. This is what drawing code looks like. var g_graph = new google.visualization.AnnotatedTimeLine(document.getElementById('graph_div_json')); var table = new google.visualization.Table(document.getElementById('table_div_json')); function handleQueryResponse(response){ log("Drawing graph") var data = response.getDataTable() g_graph.draw(data, {allowRedraw:true, thickness:2, fill:50, scaleType:'maximized'}) table.draw(data, {allowRedraw:true}) } I am try to find a way for it to only displaying the data that is in the DataTable. I have tried removing the allowRedraw flag but then it breaks the zooming operation. Any help would be greatly appreciated. Thanks

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  • Accessing Element Count and Values Within a Hidden Div

    - by Tegan Snyder
    I'm having trouble grabbing the TR count in JQuery of a table that inside a DIV set to be hidden. Here is an example: <div id="questions" style="display: none;"> <table id="tbl_questions"> <thead> <tr> <th>Question</th> <th>Weight</th> </tr> </thead> <tbody> <tr id="q0"> <td id="td_question0">Some Question 0</td> <td id="td_wieght0">Some Weight 0</td> </tr> <tr id="q1"> <td id="td_question1">Some Question 1</td> <td id="td_wieght1">Some Weight 1</td> </tr> </tbody> </table> </div> Note the table is within the containing div. It's set to display: none. When I try to run this JQuery code it returns 0. var question_count = $("#tbl_questions> tr").size(); alert(question_count); Any ideas? I'm try to locate the count so I can then build an array of each question and weight in the table. Since the ID's provide me with an index this should be simple, but is the fact that it is contained in a hidden DIV going to be a problem just as the above question? Thanks, Tegan Snyder

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  • Order database results by bayesian rating

    - by One Trick Pony
    I'm not sure this is even possible, but I need a confirmation before doing it the "ugly" way :) So, the "results" are posts inside a database which are stored like this: the posts table, which contains all the important stuff, like the ID, the title, the content the post meta table, which contains additional post data, like the rating (this_rating) and the number of votes (this_num_votes). This data is stored in pairs, the table has 3 columns: post ID / key / value. It's basically the WordPress table structure. What I want is to pull out the highest rated posts, sorted based on this formula: br = ( (avg_num_votes * avg_rating) + (this_num_votes * this_rating) ) / (avg_num_votes + this_num_votes) which I stole form here. avg_num_votes and avg_rating are known variables (they get updated on each vote), so they don't need to be calculated. Can this be done with a mysql query? Or do I need to get all the posts and do the sorting with PHP?

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  • temporary tables within stored procedures on slave servers with readonly set

    - by lau
    Hi, We have set up a replication scheme master/slave and we've had problems lately because some users wrote directly on the slave instead of the master, making the whole setup inconsistent. To prevent these problems from happening again, we've decided to remove the insert, delete, update, etc... rights from the users accessing the slave. Problems is that some stored procedure (for reading) require temporary tables. I read that changing the global variable read_only to true would do what I want and allow the stored procedures to work correctly ( http://dev.mysql.com/doc/refman/5.0/en/server-system-variables.html#sysvar_read_only ) but I keep getting the error : The MySQL server is running with the --read-only option so it cannot execute this statement (1290) The stored procedure that I used (for testing purpose) is this one : DELIMITER $$ DROP PROCEDURE IF EXISTS test_readonly $$ CREATE DEFINER=dbuser@% PROCEDURE test_readonly() BEGIN CREATE TEMPORARY TABLE IF NOT EXISTS temp ( BT_INDEX int(11), BT_DESC VARCHAR(10) ); INSERT INTO temp (BT_INDEX, BT_DESC) VALUES (222,'walou'), (111,'bidouille'); DROP TABLE temp; END $$ DELIMITER ; The create temporary table and the drop table work fine with the readonly flag - if I comment the INSERT line, it runs fine- but whenever I want to insert or delete from that temporary table, I get the error message. I use Mysql 5.1.29-rc. My default storage engine is InnoDB. Thanks in advance, this problem is really driving me crazy.

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  • NSTableView with columns bound to different NSArrayControllers

    - by Vyacheslav Karpukhin
    i have NSTableView and two columns in it: NSTableColumn *column = [[[NSTableColumn alloc] initWithIdentifier:@"custId"] autorelease]; [column bind:@"value" toObject:arrC2 withKeyPath:@"arrangedObjects.custId" options:nil]; [table addTableColumn:column]; column = [[[NSTableColumn alloc] initWithIdentifier:@"totalGrams"] autorelease]; [column bind:@"value" toObject:valuationArrC withKeyPath:@"arrangedObjects.totalGrams_double" options:nil]; [table addTableColumn:column]; as you can see, columns bound to different NSArrayControllers. first column shows correct values, but second just shows "(" symbol. but if i swap columns like this: NSTableColumn *column = [[[NSTableColumn alloc] initWithIdentifier:@"totalGrams"] autorelease]; [column bind:@"value" toObject:valuationArrC withKeyPath:@"arrangedObjects.totalGrams_double" options:nil]; [table addTableColumn:column]; column = [[[NSTableColumn alloc] initWithIdentifier:@"custId"] autorelease]; [column bind:@"value" toObject:arrC2 withKeyPath:@"arrangedObjects.custId" options:nil]; [table addTableColumn:column]; then i see values of first column (which was second in the first example) and again "(" in the second column. i don't understand that behaviour. how can i bound two array controllers to one table?

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  • How to structure a database with questions and answers?

    - by Andreas Johannessen
    Hi I am going to make a simple application that uses a database. I could need some guidance on how to structure it. I shall make question program. What I have in mind is. One table with questions One table with the difficulity of the question One table with the category of the question However, what do I do with the answers? Have them as seperate columns in the question-table? It sounds like a bad practice.(Also, where do I have the correct answer) Each question will have 5 answers where only one of them is correct.

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  • Reverse Expression.Like criterion

    - by Joel Potter
    How should I go about writing a backwards like statement using NHibernate criteria? WHERE 'somestring' LIKE [Property] + '%' Sub Question: Can you access the abstract root alias in a SQLCriterion expression? This is somewhat achievable using the SQLCriterion expression Expression.Sql("? like {alias}.[Property] + '.%'", value, NHibernateUtil.String); However, in the case of class inheritance, {alias} is replaced with the incorrect alias for the column. Example (these classes are stored in separate tables): public abstract class Parent { public virtual string Property { get; set; } } public class Child : Parent { } The above query executed with Child as the root type will replace {alias} with the alias to the Child table rather than the Parent table. This results in an invalid column exception. I need to execute a like statement as above where the property exists on the parent table rather than on the root type table.

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  • Mysql Removal of primary key

    - by marionmaiden
    Hello, I've removed the primary key of one table of my MySQL database, but now, when I use the MySQL Administrator and try to edit the data of this table, it doesn't allow me to do this. The button edit that appears in the bottom of the table keeps visible, but unable to click.

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