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  • count(*) vs count(column-name) - which is more correct?

    - by bread
    Does it make a difference if you do count(*) vs count(column-name) as in these two examples? I have a tendency to always write count(*) because it seems to fit better in my mind with the notion of it being an aggregate function, if that makes sense. But I'm not sure if it's technically best as I tend to see example code written without the * more often than not. count(*): select customerid, count(*), sum(price) from items_ordered group by customerid having count(*) > 1; vs. count(column-name): SELECT customerid, count(customerid), sum(price) FROM items_ordered GROUP BY customerid HAVING count(customerid) > 1;

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  • Mutiple FK columns all pointing to the same parent table - a good idea?

    - by Randy Minder
    For those of you who live and breath database design, have you ever found compelling reasons to have multiple FK's in a table that all point to the same parent table? We recently had to deal with a situation where we had a table that contained six columns which were all FK columns to the same parent table. We're debating whether this indicates a poor design on our part or whether this is more common than we think. Thanks very much.

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  • How do I execute a sql statement through a variable (dyname sql) that tries to do an insert into a variable table?

    - by Testifier
    If I do what I wanna do with a TEMPORARY TABLE, it works fine: DECLARE @CTRFR VARCHAR(MAX) SET @CTRFR = 'select blah blah blah' -- <-- very long select statement. this returns a 0 or some greater number. Please note! --> I NEED THIS NUMBER. IF EXISTS ( SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo][#CTRFRResult]') AND type IN ( N'U' ) ) DROP TABLE [dbo].[#CTRFRResult] CREATE TABLE #CTRFRResult ( CTRFRResult VARCHAR(MAX) ) SET @CTRFR = 'insert into #CTRFRResult ' + @CTRFR EXEC(@CTRFR) The above works fine. The problem is that several databases are using the same TEMP table. Therefore I need to use a VARIABLE table (instead of a temporary table). What I have below is not working because it says that the table must be declared. DECLARE @CTRFRResult TABLE ( CTRFRResult VARCHAR(MAX) ) SET @CTRFR = 'insert into @CTRFRResult ' + @CTRFR -- I think the issue is here. EXEC(@CTRFR) Setting @CTRFR to 'insert into...' is not working because I'm assuming the table name is out of scope. How would I go about mimicking the temporary table code using a variable table?

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  • How to filter rows on a complex filter

    - by dan
    I have these rows in a table ID Name Price Delivery == ==== ===== ======== 1 apple 1 1 2 apple 3 2 3 apple 6 3 4 apple 9 4 5 orange 4 6 6 orange 5 7 I want to have the price at the third delivery (Delivery=3) or the last price if there's no third delivery. It would give me this : ID Name Price Delivery == ==== ===== ======== 3 apple 6 3 6 orange 5 7 I don't necessary want a full solution but an idea of what to look for would be greatly appreciated.

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  • Timeout not working in SQL Connection

    - by carlos
    I have this simple code to test that a DB is ready: Function testlocalcon() As Boolean Dim constr As String = _clconstr Try Using t As New SqlConnection() constr = constr & " ; Connect Timeout=1" If Not t.State = Data.ConnectionState.Open Then t.ConnectionString = constr t.Open() If t.State = Data.ConnectionState.Open Then Return True Else Return False End If Else Return True End If End Using Catch ex As Exception Return False End Try End Function I do not want to execute a query, just to check the connection, but no matter what the time out parameter is ignored. I search here (Stackoverflow) and internet and found nothing in how to fix this. Any one else have this problem? Or, are there any other ideas on how to let the application know that the DB is ready?

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  • How can I find columns which have non-null values?

    - by aartist
    I have many columns in oracle database and some new are added with values. I like to find out which columns have values other than 0 or null. So I am looking for column names for which some sort of useful values exists at least in one row. How do I do this? Update: This sounds very close. How do I modify this to suit my needs? select column_name, nullable, num_distinct, num_nulls from all_tab_columns where table_name = 'SOME_TABLE'

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  • Determining child count of path

    - by sqlnewbie
    I have a table whose 'path' column has values and I would like to update the table's 'child_count' column so that I get the following output. path | child_count --------+------------- | 5 /a | 3 /a/a | 0 /a/b | 1 /a/b/c | 0 /b | 0 My present solution - which is way too inefficient - uses a stored procedure as follows: CREATE FUNCTION child_count() RETURNS VOID AS $$ DECLARE parent VARCHAR; BEGIN FOR parent IN SELECT path FROM my_table LOOP DECLARE tokens VARCHAR[] := REGEXP_SPLIT_TO_ARRAY(parent, '/'); str VARCHAR := ''; BEGIN FOR i IN 2..ARRAY_LENGTH(tokens, 1) LOOP UPDATE my_table SET child_count = child_count + 1 WHERE path = str; str := str || '/' || tokens[i]; END LOOP; END; END LOOP; END; $$ LANGUAGE plpgsql; Anyone knows of a single UPDATE statement that does the same thing?

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  • SQL Server Reporting Services using of pictures with dynamic links

    - by YvesR
    I have setup a SSRS 2008 and building reports. So far so good. Now there is a picture control in SSRS where you can set the picture as external link reference. There you can choose to use a link. When I use a weblink (http://anyurl/download_picture.aspx?id=123) it dont' work for me. Calling the url in the web browser (all tested IE, Safari, Chrome, FF) the pictures is delivered, Header is ok, content type, too. Does it work in general in SSRS ? Or do I have to copy the picture to a temp folder and link the url like http://anyurl/mypicture.jpg.

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  • MySQL Multiple "AND" Query

    - by Mark J
    I have a table with 2 columns (see below). A member can have multiple responses to a question RESPONSES --------- member_id INT response_id INT SAMPLE DATA member_id -- response_id 1 -- 3 1 -- 5 2 -- 1 2 -- 5 2 -- 9 3 -- 1 3 -- 5 3 -- 6 What I need to do is query the table for member that meet ALL response criteria. For example I need to select all members that have a response_id of 1 AND 5. I am using the following query: SELECT DISTINCT member_id FROM responses WHERE response_id = 1 AND response_id = 5. I would expect to get back member_id's 2,3. However I am getting nothing returned. I used EXPLAIN and it shows there is an error in my where query. What am I doing wrong? Also, is there a function similar to IN where all the criteria must be met in order to return true? Thanks for your help.

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  • How can I find all records for a model without doing a long list of "OR" conditions?

    - by gomezuk
    I'm having trouble composing a CakePHP find() which returns the records I'm looking for. My associations go like this: User -(has many)- Friends , User -(has many)- Posts I'm trying to display a list of all a user's friends recent posts, in other words, list every post that was created by a friend of the current user logged in. The only way I can think of doing this is by putting all the user's friends' user_ids in a big array, and then looping through each one, so that the find() call would look something like: $posts = $this->Post->find('all',array( 'conditions' => array( 'Post.user_id' => array( 'OR' => array( $user_id_array[0],$user_id_array[1],$user_id_array[2] # .. etc ) ) ) )); I get the impression this isn't the best way of doing things as if that user is popular that's a lot of OR conditions. Can anyone suggest a better alternative?

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  • is it possible to combine will_paginate with find_by_sql?

    - by Tam
    In my rails application I want to use will_paginate plugin to paginate on my query. Is that possible? I tried doing something like this but it didn't work: @users = User.find_by_sql(" SELECT u.id, u.first_name, u.last_name, CASE WHEN r.user_accepted =1 AND (r.friend_accepted =0 || r.friend_accepted IS NULL) .........").paginate( :page => @page, :per_page => @per_page, :conditions => conditions_hash, :order => 'first_name ASC') If not, can you recommend a way around this or a way that might work as I don't want to write my own pagination.

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  • T-SQL Self Join in combination with aggregate function

    - by Nick
    Hi, i have the following table. CREATE TABLE [dbo].[Tree]( [AutoID] [int] IDENTITY(1,1) NOT NULL, [Category] [varchar](10) NULL, [Condition] [varchar](10) NULL, [Description] [varchar](50) NULL, CONSTRAINT [PK_Tree] PRIMARY KEY CLUSTERED ( [AutoID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] GO the data looks like this: INSERT INTO [Test].[dbo].[Tree] ([Category] ,[Condition] ,[Description]) VALUES ('1','Alpha','Type 1') INSERT INTO [Test].[dbo].[Tree] ([Category] ,[Condition] ,[Description]) VALUES ('1','Alpha','Type 1') INSERT INTO [Test].[dbo].[Tree] ([Category] ,[Condition] ,[Description]) VALUES ('2','Alpha','Type 2') INSERT INTO [Test].[dbo].[Tree] ([Category] ,[Condition] ,[Description]) VALUES ('2','Alpha','Type 2') go I try now to do the following: SELECT Category,COUNT(*) as CategoryCount FROM Tree where Condition = 'Alpha' group by Category but i wish also to get the Description for each Element. I tried several subqueries, self joins etc. i always come to the problem that the subquery cannot return more than one record. The problem is caused by a poor database design which i cannot change and i run out of ideas to get this done in a single query ;-(

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  • Getting #Error value from ssrs reporting

    - by deepa
    I have created a dataset with fields "LastRunBuild" and "project" .The LastRunBuild field contain string of data seperated by commas according to each project. But Some Projects have no value in LastRunBuild field.When i am using this expression " iif(Fields!LastRunBuild.Value=nothing, nothing,Split(Fields!LastRunBuild.Value,",").GetValue(3)) " a #Error value returns every time. Please reply...

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  • How to differenciate two tables

    - by Nemat
    Hi friends.... I have two tables.I want to get all records from one table that are different from the records in second table. For eg. if we have four records in first table like A,B,C,D and three records in second table thats A,B,C then the answer of query should be D. I have tried "EXCEPT" operator but it doesnt work fine.Kindly help me in writing correct query for the given problem. Any help is appreciated.... Thanks in Advance Nemat

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  • Where to start with the development of first database driven Web App (long question)?

    - by Ryan
    Hi all, I've decided to develop a database driven web app, but I'm not sure where to start. The end goal of the project is three-fold: 1) to learn new technologies and practices, 2) deliver an unsolicited demo to management that would show how information that the company stores as office documents spread across a cumbersome network folder structure can be consolidated and made easier to access and maintain and 3) show my co-workers how Test Drive Development and prototyping via class diagrams can be very useful and reduces future maintenance headaches. I think this ends up being a basic CMS to which I have generated a set of features, see below. 1) Create a database to store the site structure (organized as a tree with a 'project group'-project structure). 2) Pull the site structure from the database and display as a tree using basic front end technologies. 3) Add administrator privileges/tools for modifying the site structure. 4) Auto create required sub pages* when an admin adds a new project. 4.1) There will be several sub pages under each project and the content for each sub page is different. 5) add user privileges for assigning read and write privileges to sub pages. What I would like to do is use Test Driven Development and class diagramming as part of my process for developing this project. My problem; I'm not sure where to start. I have read on Unit Testing and UML, but never used them in practice. Also, having never worked with databases before, how to I incorporate these items into the models and test units? Thank you all in advance for your expertise.

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  • How to login users that are stored within a Wordpress account

    - by user3716795
    I am developing an iOS app that is password protected and all the users are stored in a wordpress account that, of course, is password protected as well. Does anybody know the format that wordpress uses to store login information for these accounts, I would assume that it is a MySQL that sends a json? I have only been able to find the database code for the initial admin page but nothing that shows the way these accounts (815 to be exact) would be stored within the site.

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  • self join table

    - by San82moon
    HI, i have a table, new_id----old_id----created_on 1234------5678------20100912 5678------3456------20100808 etc. i wrote this query, $q = "select event1.new_id, event1.old_id, event1.created_on,event2.new_id, event2.old_id, event2.created_on FROM replaced_isbns event1 JOIN replaced_isbns event2 ON event2.new_id = event1.old_id WHERE event1.new_id='$id'"; but i get result as 5678 - 1234, ie only one row, i want all rows... plz help me. Thanks, SLC

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  • Linqbuilder Query with an OrderBy

    - by Renshai
    I have a 1 : M relationship. I built a dynamic query based on input from users to return the listing of parents entities along with their children (using predicate builder: (done successfully new TDataContext().Ps.Where(predicate) )... but need to order the results by a field found only on the child entities. I'm at a loss: new TDataContext().Ps.Where(predicate).OrderBy(p = p.Cs. ??) where Ps = parents collection relationship with Cs = child entities any help appreciated.

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  • An attempt to attach an auto-named database for file failed in Vb.Net

    - by user2454135
    I am Trying to connect database for first time , and I am getting this error : An attempt to attach an auto-named database for file VBTestDB.mdf failed. A database with the same name exists, or specified file cannot be opened, or it is located on UNC share. and getting error on myconnect.Open() Heres my code : Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click Dim myconnect As New SqlClient.SqlConnection myconnect.ConnectionString = "Data Source=.\SQLEXPRESS;AttachDbFilename=VBTestDB.mdf;Integrated Security=True;User Instance=True;" Dim mycommand As SqlClient.SqlCommand = New SqlClient.SqlCommand() mycommand.Connection = myconnect mycommand.CommandText = "INSERT INTO Card (CardNo,Name) VALUES (@cardno,@name)" myconnect.Open() Try mycommand.Parameters.Add("@cardno", SqlDbType.Int).Value = TextBox1.Text mycommand.Parameters.Add("@name", SqlDbType.NVarChar).Value = TextBox2.Text mycommand.ExecuteNonQuery() MsgBox("Success") Catch ex As System.Data.SqlClient.SqlException MsgBox(ex.Message) End Try myconnect.Close() End Sub

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