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  • Greatest not null column

    - by Álvaro G. Vicario
    I need to update a row with a formula based on the largest value of two DATETIME columns. I would normally do this: GREATEST(date_one, date_two) However, both columns are allowed to be NULL. I need the greatest date even when the other is NULL (of course, I expect NULL when both are NULL) and GREATEST() returns NULL when one of the columns is NULL. This seems to work: GREATEST(COALESCE(date_one, date_two), COALESCE(date_two, date_one)) But I wonder... am I missing a more straightforward method?

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  • Difference between "and" and "where" in joins

    - by Midhat
    Whats the difference between SELECT DISTINCT field1 FROM table1 cd JOIN table2 ON cd.Company = table2.Name and table2.Id IN (2728) and SELECT DISTINCT field1 FROM table1 cd JOIN table2 ON cd.Company = table2.Name where table2.Id IN (2728) both return the same result and both have the same explain output

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  • Automatically Persisting a Complex Java Object

    - by VeeArr
    For a project I am working on, I need to persist a number of POJOs to a database. The POJOs class definitions are sometimes highly nested, but they should flatten okay, as the nesting is tree-like and contains no cycles (and the base elements are eventually primitives/Strings). It is preferred that the solution used create one table per data type and that the tables will have one field per primitive member in the POJO. Subclassing and similar problems are not issues for this particular project. Does anybody know of any existing solutions that can: Automatically generate a CREATE TABLE definition from the class definition Automatically generate a query to persist an object to the database, given an instance of the object Automatically generate a query to retrieve an object from the database and return it as a POJO, given a key. Solutions that can do this with minimum modifications/annotions to the class files and minimum external configuration are preferred. Example: Java classes //Class to be persisted class TypeA { String guid; long timestamp; TypeB data1; TypeC data2; } class TypeB { int id; int someData; } class TypeC { int id; int otherData; } Could map to CREATE TABLE TypeA ( guid CHAR(255), timestamp BIGINT, data1_id INT, data1_someData INT, data2_id INt, data2_otherData INT ); Or something similar.

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  • Database table schema design - varchar(n). Suitable choice of N

    - by morpheous
    Coming from a C background, I may be getting too anal about this and worrying unnecessarily about bits and bytes here. Still, I cant help thinking how the data is actually stored and that if I choose an N which is easily factorizable into a power of 2, the database will be more effecient in how it packs data etc. Using this "logic", I have a string field in a table which is a variable length up to 21 chars. I am tempted to use 32 instead of 21, for the reason given above - however now I am thinking that I am wasting disk space because there will be space allocated for 11 extra chars that are guaranteed to be never used. Since I envisage storing several tens of thousands of rows a day, it all adds up. Question: Mindful of all of the above, Should I declare varchar(21) or varchar(32) and why?

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  • Improve SQL query performance

    - by Anax
    I have three tables where I store actual person data (person), teams (team) and entries (athlete). The schema of the three tables is: In each team there might be two or more athletes. I'm trying to create a query to produce the most frequent pairs, meaning people who play in teams of two. I came up with the following query: SELECT p1.surname, p1.name, p2.surname, p2.name, COUNT(*) AS freq FROM person p1, athlete a1, person p2, athlete a2 WHERE p1.id = a1.person_id AND p2.id = a2.person_id AND a1.team_id = a2.team_id AND a1.team_id IN ( SELECT id FROM team, athlete WHERE team.id = athlete.team_id GROUP BY team.id HAVING COUNT(*) = 2 ) GROUP BY p1.id ORDER BY freq DESC Obviously this is a resource consuming query. Is there a way to improve it?

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  • Do partitions allow multiple bulk loads?

    - by ck
    I have a database that contains data for many "clients". Currently, we insert tens of thousands of rows into multiple tables every so often using .Net SqlBulkCopy which causes the entire tables to be locked and inaccessible for the duration of the transaction. As most of our business processes rely upon accessing data for only one client at a time, we would like to be able to load data for one client, while updating data for another client. To make things more fun, all PKs, FKs and clustered indexes are on GUID columns (I am looking at changing this). I'm looking at adding the ClientID into all tables, then partitioning on this. Would this give me the functionality I require?

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  • How to count number of occurences for all different values in database column?

    - by drasto
    I have a Postgre database that has say 10 columns. The fifth column is called column5. There are 100 rows in the database and possible values of column5 are c5value1, c5value2, c5value3...c5value29, c5value30. I would like to print out a table that shows how many times each value occurs. So the table would look like this: Value(of column5) number of occurrences of the value c5value1 1 c5value2 5 c5value3 3 c5value4 9 c5value5 1 c5value6 1 . . . . . . What is the command that does that? Thanks for help

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  • Getting rows which include a value with MySQL

    - by sundowatch
    I have a MySQL query which gets including some vars like that: messages TABLE receiver cols user1 rows : 1,3,5 user2 rows : 2,3 user3 rows : 1,4 I want to get rows which includes '3' value. So I will get 'user1' and 'user2'. I tried that but naturally it doesn't work. mysql_query("SELECT * FROM messages WHERE receiver='3'"); How can I do this?

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  • wp+sql+image not goin in the folder

    - by happy
    this is my code for uploading image in database but image are going to the desird forlder...but when i m tryin to retrieve the images to diaplay,,they are not displayed..anyone help me...... $category=$_POST['category']; $uploadDir = 'D:/xampp/htdocs/js/wordpress/wp-content/plugins/img/imagess/ '; $fileName = $_FILES['Photo']['name']; $tmpName = $_FILES['Photo']['tmp_name']; $fileSize = $_FILES['Photo']['size']; $fileType = $_FILES['Photo']['type']; $filePath = $uploadDir . $fileName; $result = move_uploaded_file($tmpName,$filePath); if (!$result) { echo "Error uploading file"; exit; } if(!get_magic_quotes_gpc()) { $fileName = addslashes($fileName); $filePath = addslashes($filePath); } global $wpdb; //$insert=$wpdb->insert('images',array('image_name'=>$filePath,'cat_name'=>$category),array('%b','%s')); $insert=$wpdb->insert('images',array('image_name'=>$filePath,'cat_name'=>$category)); $wpdb->insert('categories',array('cat_name'=>$category)); echo "Successfully Submitted";

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  • Getting records from a table based on a filter field and Between but also having the OR login for mu

    - by Pentium10
    I have a this table, where I store multiple ids and an age range (def1,def2) CREATE TABLE "template_requirements" ("_id" INTEGER NOT NULL, "templateid" INTEGER, "def1" VARCHAR(255), "def2" VARCHAR(255), PRIMARY KEY("_id")) Having values such as: templateid | def1 | def2 100 | 7 | 25 200 | 40 | 90 300 | 7 | 25 300 | 40 | 60 as you see for templateid 300 we have an or logic: age between 7 and 25 or age between 40 and 60. I want to get all the template ids that are not for a certain age like 25... What's the problem? If I run a query like this one: SELECT group_concat(templateid) FROM template_requirements where and '25' not between cast(def1 as integer) and cast(def2 as integer) it returns 200, 300, which is wrong, as the 300 matched on row 40 to 60, but shouldn't be included in the result as we have a condition with same templateid 7 to 25 that fails the not beetween stuff. How would be the correct query in SQLite, I would like to keep the group_concat stuff.

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  • Best method to search heriarachal data

    - by WDuffy
    I'm looking at building a facility which allows querying for data with hierarchical filtering. I have a few ideas how I'm going to go about it but was wondering if there are any recommendations or suggestions that might be more efficient. As an example imagine that a user is searching for a job. The job areas would be as follows. 1: Scotland 2: --- West Central 3: ------ Glasgow 4: ------ Etc 5: --- North East 6: ------ Ayrshire 7: ------ Etc A user can search specific (ie Glasgow) or in a larger area (ie Scotland). The two approaches I am considering are 1: keep a note of children in the database for each record (ie cat 1 would have 2, 3, 4 in its children field) and query against that record with a SELECT * FROM Jobs WHERE Category IN Areas.childrenField. 2: Use a recursive function to find all results who have a relation to the selected area The problems I see from both are 1: holding this data in the db will mean having to keep track of all changes to structure 2: Recursion is slow and inefficent Any ideas, suggestion or recommendations on the best approach? I'm using C# ASP.NET with MSSQL 2005 DB.

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  • Adding Related Entities without using navigation properties

    - by Barisa Puter
    I have the following classes, set for testing: public class Company { [DatabaseGenerated(DatabaseGeneratedOption.Identity)] public int Id { get; set; } public string Name { get; set; } } public class Employee { [DatabaseGenerated(DatabaseGeneratedOption.Identity)] public int Id { get; set; } public string Name { get; set; } public int CompanyId { get; set; } public virtual Company Company { get; set; } } public class EFTestDbContext : DbContext { public DbSet<Employee> Employees { get; set; } public DbSet<Company> Companies { get; set; } } For the sake of testing, I wanted to insert one company and one employee for that company with single SaveChanges call, like this: Company company = new Company { Name = "Sample company" }; context.Companies.Add(company); // ** UNCOMMENTED FOR TEST 2 //Company company2 = new Company //{ // Name = "Some other company" //}; //context.Companies.Add(company2); Employee employee = new Employee { Name = "Hans", CompanyId = company.Id }; context.Employees.Add(employee); context.SaveChanges(); Even though I am not using navigational properties, but instead I've made relation over Id, this somehow mysteriously worked - employee was saved with proper foreign key to company which got updated from 0 to real value, which made me go ?!?! Some hidden C# feature? Then I've decided to add more code, which is commented in the snippet above, making it to be inserting of 2 x Company entity and 1 x Employee entity, and then I got exception: Unable to determine the principal end of the 'CodeLab.EFTest.Employee_Company' relationship. Multiple added entities may have the same primary key. Does this mean that in cases where foreign key is 0, and there is a single matching entity being inserted in same SaveChanges transaction, Entity Framework will assume that foreign key should be for that matching entity? In second test, when there are two entities matching the relation type, Entity Framework throws an exception as it is not able to figure out to which of the Companies Employee should be related to.

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  • how to select distinct rows for a column

    - by Satoru.Logic
    Hi, all. I have a table x that's like the one bellow: id | name | observed_value | 1 | a | 100 | 2 | b | 200 | 3 | b | 300 | 4 | a | 150 | 5 | c | 300 | I want to make a query so that in the result set I have exactly one record for one name: (1, a, 100) (2, b, 200) (5, c, 300) If there are multiple records corresponding to a name, say 'a' in the table above, I just pick up one of them. In my current implementation, I make a query like this: select x.* from x , (select distinct name, min(observed_value) as minimum_val from x group by name) x1 where x.name = x1.name and x.observed_value = x1.observed_value; But I think there may be some better way around, please tell me if you know, thanks in advance.

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  • Notification 7 Days Before Payment PHP No Error Message

    - by user1858672
    So I have PHP script running on cron daily. It is suppose to check the date and send an email if it is 7 days before any payments as a reminder. I haven't used PHP in a long time so sorry if the way I did it was ridiculous or something. Thanks a lot. I would say what the problem is but I don't get any error message or anything.. <?php mysqli_connect("xxxxxx", "xxxxxxx", "xxxxxxxxx") or die(mysqli_error()); mysqli_select_db("xxxxxxxxx") or die(mysqli_error()); //Retrieve original payment dates and enter them into an array $result = mysqli_query("SELECT DateCreated FROM UserTable"); $payment_dates = mysqli_fetch_array($result); //Puts original payment date into month-day format $md_payment_dates = substr($payment_dates, 5); //Gets todays date in m-d format and adds 7 days to it $due_date = mktime(0, 0, 0, date("m"), date("d")+7); //Checks if any payment days match today's date. If there are none it script will stop. if (count(preg_grep($due_date, $md_payment_dates)) > 0) { //Retrieves usernames of users that have an invoice due. $users_to_pay = mysqli_fetch_array("SELECT Username IN UserTable WHERE DateCreated = $date"); //Notifies you via email $to = "[email protected]"; $subject = "7 Day Payment Reminder"; $message = "Hi, <br /> The following owe a payment in 7 days : " + $users_to_pay ".<br/> Their payments are due on " + $md_payment_dates " of this year."; mail($to, $subject, $message); exit(); }else{ exit(); } ?>

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  • how to get an xml in a variable

    - by sam
    I have a stored procedure that will return xml. I have delared a variable of type xml and trying to execute the following code declare @v xml set @v = execute get_xml @id, 33 whereas id is returned by another query. now it keeps compalinng about the following error Incorrect syntax near the keyword 'execute'.

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  • MySQL - Limit a left join to the first date-time that occurs?

    - by John M
    Simplified table structure (the tables can't be merged at this time): TableA: dts_received (datetime) dts_completed (datetime) task_a (varchar) TableB: dts_started (datetime) task_b (varchar) What I would like to do is determine how long a task took to complete. The join parameter would be something like ON task_a = task_b AND dts_completed < dts_started The issue is that there may be multiple date-times that occur after the dts_completed. How do I create a join that only returns the first tableB-datetime that occurs after the tableA-datetime?

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  • C#: ExecuteNonQuery() returns -1 when execute the stored procedure

    - by user1122359
    I'm trying to execute stored procedure in Visual Studio. Its given below. CREATE PROCEDURE [dbo].[addStudent] @stuName varchar(50), @address varchar(100), @tel varchar(15), @etel varchar(15), @nic varchar (10), @dob date AS BEGIN SET NOCOUNT ON; DECLARE @currentID INT DECLARE @existPerson INT SET @existPerson = (SELECT p_ID FROM Student WHERE s_NIC = @nic); IF @existPerson = null BEGIN INSERT INTO Person (p_Name, p_RegDate, p_Address, p_Tel, p_EmergeNo, p_Valid, p_Userlevel) VALUES (@stuName, GETDATE(), @address, @tel, @etel, 0, 'Student' ); SET @currentID = (SELECT MAX( p_ID) FROM Person); INSERT INTO Student (p_ID, s_Barcode, s_DOB, s_NIC) VALUES (@currentID , NULL, @dob, @nic); return 0; END ELSE return -1; END Im doing so by using this code below. SqlConnection con = new SqlConnection(); Connect conn = new Connect(); con = conn.getConnected(); con.Open(); cmd = new SqlCommand("addStudent", con); cmd.CommandType = CommandType.StoredProcedure; cmd.Parameters.Add("@stuName", SqlDbType.VarChar).Value = nameTxt.Text.ToString(); cmd.Parameters.Add("@address", SqlDbType.VarChar).Value = addressTxt.Text.ToString(); cmd.Parameters.Add("@tel", SqlDbType.VarChar).Value = telTxt.Text.ToString(); cmd.Parameters.Add("@etel", SqlDbType.VarChar).Value = emerTxt.Text.ToString(); cmd.Parameters.Add("@nic", SqlDbType.VarChar).Value = nicTxt.Text.ToString(); cmd.Parameters.Add("@dob", SqlDbType.DateTime).Value = dobTime.Value.ToString("MM-dd-yyyy"); int n = cmd.ExecuteNonQuery(); MessageBox.Show(n.ToString()); But it returns me -1. I tried this stored procedure by entering the same values I captured from debugging. It was successful. What can be the possible error? Thanks a lot!

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  • Insert into select and update in single query

    - by Ossi
    I have 4 tables: tempTBL, linksTBL and categoryTBL, extra on my tempTBL I have: ID, name, url, cat, isinserted columns on my linksTBL I have: ID, name, alias columns on my categoryTBL I have: cl_id, link_id,cat_id on my extraTBL I have: id, link_id, value How do I do a single query to select from tempTBL all items where isinsrted = 0 then insert them to linksTBL and for each record inserted, pickup ID (which is primary) and then insert that ID to categoryTBL with cat_id = 88. after that insert extraTBL ID for link_id and url for value. I know this is so confusing, put I'll post this anyhow... This is what I have so far: INSERT IGNORE INTO linksTBL (link_id,link_name,alias) VALUES(NULL,'tex2','hello'); # generate ID by inserting NULL INSERT INTO categoryTBL (link_id,cat_id) VALUES(LAST_INSERT_ID(),'88'); # use ID in second table I would like to add here somewhere that it only selects items where isinserted = 0 and iserts those records, and onse inserted, will change isinserted to 1, so when next time it runs, it will not add them again.

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  • Centralizing / Abstracting MSSQL Data from Multiple Tables / Databases

    - by davemackey
    If one has a number of databases (due to separate application front-ends) that provide a complete picture - for example a CRM, accounting, and product database - what methods are available to centralize/abstract this data for easy reporting? Essentially, I'm wondering if there is a way to automatically pull data from multiple databases into a central repository that is continuously updated from the three databases and which can be used for reporting? I'm also open to alternative best practice suggestions?

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  • Cakephp Autoconvert find() fields?

    - by Razor Storm
    In cake php I can grab a model's fields by using the find() method. What if I wish to apply a transformation function to the fields? Is there a way to directly accomplish this task? Suppose I have a model called RaceTime with the fields racerId and timeMillis RaceTime +------------+ | Field | +------------+ | id | | racerId | | timeMillis | +------------+ timeMillis is an int specifying how long the race took in milliseconds. Obviously saying a race took 15651 milliseconds isn't very useful to a human reader, and I would wish to convert this to a human readable format. Is there a way to accomplish this directly in find()? Or is the only option to loop through the results after find() finishes?

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  • How to handle Foreign Keys with Entity Framework

    - by Jack Marchetti
    I have two entities. Groups. Pools. A Group can create many pools. So I setup my Pool table to have a GroupID foreign key. My code: using (entity _db = new entity()) { Pool p = new Pool(); p.Name = "test"; p.Group.ID = "5"; _db.AddToPool(p); } This doesn't work. I get a null reference exception on p.Group. How do I go about creating a new "Pool" and associating a GroupID?

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  • comparing rows on a mysql table

    - by user311324
    Ok here's the deal I got one table with a bunch of client information. Each client makes up to one purchase a year which is represented by an individual row. there's a column for the year and there's a column the contains a unique identifier for each client. What I need to do is to construct a query that takes last year and this year and shows me which clients were here made a purchase last year but not make a purchase this year. I also need to build a query that shows me which clients did not make a purchase last year and the year before last but did make a purchase this year.

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