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  • mysql GROUP_CONCAT

    - by user301766
    I want to list all users with their corropsonding user class. Here are simplified versions of my tables CREATE TABLE users ( user_id INT NOT NULL AUTO_INCREMENT, user_class VARCHAR(100), PRIMARY KEY (user_id) ); INSERT INTO users VALUES (1, '1'), (2, '2'), (3, '1,2'); CREATE TABLE classes ( class_id INT NOT NULL AUTO_INCREMENT, class_name VARCHAR(100), PRIMARY KEY (class_id) ); INSERT INTO classes VALUES (1, 'Class 1'), (2, 'Class 2'); And this is the query statement I am trying to use but is only returning the first matching user class and not a concatenated list as hoped. SELECT user_id, GROUP_CONCAT(DISTINCT class_name SEPARATOR ",") AS class_name FROM users, classes WHERE user_class IN (class_id) GROUP BY user_id; Actual Output +---------+------------+ | user_id | class_name | +---------+------------+ | 1 | Class 1 | | 2 | Class 2 | | 3 | Class 1 | +---------+------------+ Wanted Output +---------+---------------------+ | user_id | class_name | +---------+---------------------+ | 1 | Class 1 | | 2 | Class 2 | | 3 | Class 1, Class 2 | +---------+---------------------+ Thanks in advance

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  • How can I save the schema of a SQL Database to a file?

    - by Eric
    I'm writing a software application in C#.Net that connects to a SQL Server database. My C# project is under SVN version control, but I'd like to include my database schema in the SVN repository as well. An answer to a previous question of mine suggested storing the scripts to generate the database in version control. Is there a way to automatically generate these scripts from an existing database? I'm very new to SQL Server, but I noticed in management studio that the SQL commands to create a table can be generated automatically by right clicking on the table and clicking "Script Table As". Is there an equivalent command that would work with the entire database?

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  • What is faster in MySQL? WHERE sub request = 0 or IN list

    - by Nicolas Manzini
    Hello I was wondering what is better in MySQL. I have a SELECT querry that exclude every entry associated to a banned userID currently I have a subquerry clause in the WHERE statement that goes like AND (SELECT COUNT(*) FROM TheBlackListTable WHERE userID = userList.ID AND blackListedID = :userID2 ) = 0 Which will accept every userID not present in the TheBlackListTable Would it be faster to retrieve first all Banned ID in a previous request and replace the previous clause by AND creatorID NOT IN listOfBannedID Thank you!

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  • DB design for master file in enterprise software

    - by Thang Nguyen
    Dear all. I want to write an enterprise software and now I'm in the DB design phase. The software will have some master data such as Suppliers, Customers, Inventories, Bankers... I considering 2 options: Put each of these on one separate table. The advantage: the table will have all necessary information for that kind of master file (Customer: name, address,.../Inventory: Type, Manufacturer, Condition...). Disadvantage: Not flexible. When I want to have a new type of master data, such as Insurer, I have to design another table. Put all in one table and this table have foreign key to another table which have type of each kind of master data (table 1: id, data_type, code, name, address....; table 2: data_type, data_type_name). Advantage: flexible - if I want more master data such as Insurer, I just put in table 2: code: 002, name: Insurer, and then put detail each insurer into table 1). Disadvantage: table 1 must have sufficient field to store all kind of information including: customer name, address, account, inventory's manufacturer, inventory's quality...). So which method do you usually do (or you think work better). Thank you very much

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  • Advice on simple efficient way to store web form data when no db/auth required

    - by ted776
    Hi, I have a situation where I need to provide an efficient way to process and store comments submitted via a web form. I would normally use PHP and either MySQL or XML to store the data, but this is slightly different in that this web form will only be temporarily available in a closed LAN environment, and all i need to do is process the form data and store it a format which can be accessed by another application on the LAN (Adobe Director). Each request made by the Director app should pop the stack of data. I'm wondering how best to store the data for this type of situation as it's not something I would normally do. I'm thinking possibly storing the data in an XML file, but any advice would be great!

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  • Sql server query using function and view is slower

    - by Lieven Cardoen
    I have a table with a xml column named Data: CREATE TABLE [dbo].[Users]( [UserId] [int] IDENTITY(1,1) NOT NULL, [FirstName] [nvarchar](max) NOT NULL, [LastName] [nvarchar](max) NOT NULL, [Email] [nvarchar](250) NOT NULL, [Password] [nvarchar](max) NULL, [UserName] [nvarchar](250) NOT NULL, [LanguageId] [int] NOT NULL, [Data] [xml] NULL, [IsDeleted] [bit] NOT NULL,... In the Data column there's this xml <data> <RRN>...</RRN> <DateOfBirth>...</DateOfBirth> <Gender>...</Gender> </data> Now, executing this query: SELECT UserId FROM Users WHERE data.value('(/data/RRN)[1]', 'nvarchar(max)') = @RRN after clearing the cache takes (if I execute it a couple of times after each other) 910, 739, 630, 635, ... ms. Now, a db specialist told me that adding a function, a view and changing the query would make it much more faster to search a user with a given RRN. But, instead, these are the results when I execute with the changes from the db specialist: 2584, 2342, 2322, 2383, ... This is the added function: CREATE FUNCTION dbo.fn_Users_RRN(@data xml) RETURNS varchar(100) WITH SCHEMABINDING AS BEGIN RETURN @data.value('(/data/RRN)[1]', 'varchar(max)'); END; The added view: CREATE VIEW vwi_Users WITH SCHEMABINDING AS SELECT UserId, dbo.fn_Users_RRN(Data) AS RRN from dbo.Users Indexes: CREATE UNIQUE CLUSTERED INDEX cx_vwi_Users ON vwi_Users(UserId) CREATE NONCLUSTERED INDEX cx_vwi_Users__RRN ON vwi_Users(RRN) And then the changed query: SELECT UserId FROM Users WHERE dbo.fn_Users_RRN(Data) = '59021626919-61861855-S_FA1E11' Why is the solution with a function and a view going slower?

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  • Passing BLOB/CLOB as parameter to PL/SQL function

    - by Ula Krukar
    I have this procedure i my package: PROCEDURE pr_export_blob( p_name IN VARCHAR2, p_blob IN BLOB, p_part_size IN NUMBER); I would like for parameter p_blob to be either BLOB or CLOB. When I call this procedure with BLOB parameter, everything is fine. When I call it with CLOB parameter, I get compilation error: PLS-00306: wrong number or types of arguments in call to 'pr_export_blob' Is there a way to write a procedure, that can take either of those types as parameter? Some kind of a superclass maybe?

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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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  • Cassandra Production ready on Windows?

    - by BlackTea
    Question anyone know of any success stories of Cassandra running on windows in a production environment? I'm doing some work on Cassandra and trying to find the correct platform for it currently the platform is windows running MS-SQLas the data store. what are the dis-advantages if any when running Cassandra on a windows environment.

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  • Single Large v/s Multiple Small MySQL tables for storing Options

    - by Prasad
    Hi there, I'm aware of several question on this forum relating to this. But I'm not talking about splitting tables for the same entity (like user for example) Suppose I have a huge options table that stores list options like Gender, Marital Status, and many more domain specific groups with same structure. I plan to capture in a OPTIONS table. Another simple option is to have the field set as ENUM, but there are disadvantages of that as well. http://www.brandonsavage.net/why-you-should-replace-enum-with-something-else/ OPTIONS Table: option_id <will be referred instead of the name> name value group Query: select .. from options where group = '15' - Since this table is expected to be multi-tenant, the no of rows could grow drastically. - I believe splitting the tables instead of finding by the group would be easier to write & faster to execute. - or perhaps partitioning by the group or tenant? Pl suggest. Thanks

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  • MongoDB RSS Feed Entries, Embed the Entries in the Feed Object?

    - by Patrick Klingemann
    I am saving a reference to an RSS Feed in MongoDB, each Feed has an ever growing list of Entries. As I'm designing my schema, I'm concerned about this statement from the MongoDB Schema Design - Embed vs. Reference Documentation: If the amount of data to embed is huge (many megabytes), you may read the limit on size of a single object. This will surely happen if I understand the statement correctly. So the question is, I am correct to assume that I should not embed the Feed Entries within a Feed because I'll eventually reach the limit on size of a single object?

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  • Using memory-based cache together with conventional cache

    - by Industrial
    Hi! Here's the deal. We would have taken the complete static html road to solve performance issues, but since the site will be partially dynamic, this won't work out for us. What we have thought of instead is using memcache + eAccelerator to speed up PHP and take care of caching for the most used data. Here's our two approaches that we have thought of right now: Using memcache on all<< major queries and leaving it alone to do what it does best. Usinc memcache for most commonly retrieved data, and combining with a standard harddrive-stored cache for further usage. The major advantage of only using memcache is of course the performance, but as users increases, the memory usage gets heavy. Combining the two sounds like a more natural approach to us, even though the theoretical compromize in performance. Memcached appears to have some replication features available as well, which may come handy when it's time to increase the nodes. What approach should we use? - Is it stupid to compromize and combine the two methods? Should we insted be focusing on utilizing memcache and instead focusing on upgrading the memory as the load increases with the number of users? Thanks a lot!

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  • How do I get save (no exclamation point) semantics in an ActiveRecord transaction?

    - by James A. Rosen
    I have two models: Person and Address which I'd like to create in a transaction. That is, I want to try to create the Person and, if that succeeds, create the related Address. I would like to use save semantics (return true or false) rather than save! semantics (raise an ActiveRecord::StatementInvalid or not). This doesn't work because the user.save doesn't trigger a rollback on the transaction: class Person def save_with_address(address_options = {}) transaction do self.save address = Address.build(address_options) address.person = self address.save end end end (Changing the self.save call to an if self.save block around the rest doesn't help, because the Person save still succeeds even when the Address one fails.) And this doesn't work because it raises the ActiveRecord::StatementInvalid exception out of the transaction block without triggering an ActiveRecord::Rollback: class Person def save_with_address(address_options = {}) transaction do save! address = Address.build(address_options) address.person = self address.save! end end end The Rails documentation specifically warns against catching the ActiveRecord::StatementInvalid inside the transaction block. I guess my first question is: why isn't this transaction block... transacting on both saves?

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  • Strategy in storing ad-hoc numbers/constants?

    - by Jiho Han
    I have a need to store a number of ad-hoc figures and constants for calculation. These numbers change periodically but they are different type of values. One might be a balance, a money amount, another might be an interest rate, and yet another might be a ratio of some kind. These numbers are then used in a calculation that involve other more structured figures. I'm not certain what the best way to store these in a relational DB is - that's the choice of storage for the app. One way, I've done before, is to create a very generic table that stores the values as text. I might store the data type along with it but the consumer knows what type it is so, in situations I didn't even need to store the data type. This kind of works fine but I am not very fond of the solution. Should I break down each of the numbers into specific categories and create tables that way? For example, create Rates table, and Balances table, etc.?

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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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  • Multi-variable indexes in postgres

    - by Jackson Davis
    Im looking at an application where I will be doing quite a few SELECTs where I am trying to find column_a = x AND column_b = y. Is the correct to create that index that something like the following? CREATE INDEX index_name ON table (column_a, column_b)

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  • Do non-clustered indexes slow down inserts?

    - by mikeinmadison
    I'm working in Sql Server 2005. I have an event log table that tracks user actions, and I want to make sure that inserts into the table are as fast as possible. Currently the table doesn't have any indexes. Does adding a single non-clustered index slow down inserts at all? Or is it only clustered indexes that slow down inserts? Or should I just add a clustered index and not worry about it?

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  • Is copying /var/lib/mysql a good alterntive to mysqldump?

    - by kemp
    Since I'm making a full backup of my entire debian system, I was thinking if having a copy of /var/lib/mysql directory is a viable alternative to dumping tables with mysqldump. are all informations needed contained in that directory? can single tables be imported in another mysql? can there be problems while restoring those files on a (probably slightly) different mysql server version?

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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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  • Grails multi column indexes

    - by Kimble
    Can someone explain how to define multi column indexes in Grails? The documentation is at best sparse. This for example does not seem to work at all: http://grails.org/GORM+Index+definitions I've had some luck with this, but the results seems random at best. Definitions that works in one domain class does not when applied to another (with different names of course). http://www.grails.org/doc/1.1/guide/single.html#5.5.2.6%20Database%20Indices Some working examples and explanations would be highly appreciated!

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  • MySQL query does not return any data

    - by Alex L
    Hi, I need to retrieve data from a specific time period. The query works fine until I specify the time period. Is there something wrong with the way I specify time period? I know there are many entries within that time-frame. This query returns empty: SELECT stop_times.stop_id, STR_TO_DATE(stop_times.arrival_time, '%H:%i:%s') as stopTime, routes.route_short_name, routes.route_long_name, trips.trip_headsign FROM trips JOIN stop_times ON trips.trip_id = stop_times.trip_id JOIN routes ON routes.route_id = trips.route_id WHERE stop_times.stop_id = 5508 HAVING stopTime BETWEEN DATE_SUB(stopTime,INTERVAL 1 MINUTE) AND DATE_ADD(stopTime,INTERVAL 20 MINUTE); Here is it's EXPLAIN: +----+-------------+------------+--------+------------------+---------+---------+-------------------------------+------+-------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+------------+--------+------------------+---------+---------+-------------------------------+------+-------------+ | 1 | SIMPLE | stop_times | ref | trip_id,stop_id | stop_id | 5 | const | 605 | Using where | | 1 | SIMPLE | trips | eq_ref | PRIMARY,route_id | PRIMARY | 4 | wmata_gtfs.stop_times.trip_id | 1 | | | 1 | SIMPLE | routes | eq_ref | PRIMARY | PRIMARY | 4 | wmata_gtfs.trips.route_id | 1 | | +----+-------------+------------+--------+------------------+---------+---------+-------------------------------+------+-------------+ 3 rows in set (0.00 sec) The query works if I remove the HAVING clause (don't specify time range). Returns: +---------+----------+------------------+-----------------+---------------+ | stop_id | stopTime | route_short_name | route_long_name | trip_headsign | +---------+----------+------------------+-----------------+---------------+ | 5508 | 06:31:00 | "80" | "" | "FORT TOTTEN" | | 5508 | 06:57:00 | "80" | "" | "FORT TOTTEN" | | 5508 | 07:23:00 | "80" | "" | "FORT TOTTEN" | | 5508 | 07:49:00 | "80" | "" | "FORT TOTTEN" | | 5508 | 08:15:00 | "80" | "" | "FORT TOTTEN" | | 5508 | 08:41:00 | "80" | "" | "FORT TOTTEN" | | 5508 | 09:08:00 | "80" | "" | "FORT TOTTEN" | I am using Google Transit format Data loaded into MySQL. The query is supposed to provide stop times and bus routes for a given bus stop. For a bus stop, I am trying to get: Route Name Bus Name Bus Direction (headsign) Stop time The results should be limited only to buses times from 1 min ago to 20 min from now. Please let me know if you could help.

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