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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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  • 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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  • sqlobject: No connection has been defined for this thread or process

    - by Claudiu
    I'm using sqlobject in Python. I connect to the database with conn = connectionForURI(connStr) conn.makeConnection() This succeeds, and I can do queries on the connection: g_conn = conn.getConnection() cur = g_conn.cursor() cur.execute(query) res = cur.fetchall() This works as intended. However, I also defined some classes, e.g: class User(SQLObject): class sqlmeta: table = "gui_user" username = StringCol(length=16, alternateID=True) password = StringCol(length=16) balance = FloatCol(default=0) When I try to do a query using the class: User.selectBy(username="foo") I get an exception: ... File "c:\python25\lib\site-packages\SQLObject-0.12.4-py2.5.egg\sqlobject\main.py", line 1371, in selectBy conn = connection or cls._connection File "c:\python25\lib\site-packages\SQLObject-0.12.4-py2.5.egg\sqlobject\dbconnection.py", line 837, in __get__ return self.getConnection() File "c:\python25\lib\site-packages\SQLObject-0.12.4-py2.5.egg\sqlobject\dbconnection.py", line 850, in getConnection "No connection has been defined for this thread " AttributeError: No connection has been defined for this thread or process How do I define a connection for a thread? I just realized I can pass in a connection keyword which I can give conn to to make it work, but how do I get it to work if I weren't to do that?

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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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  • 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 limit results by SUM

    - by superspace
    I have a table of events called event. For the purpose of this question it only has one field called date. The following query returns me a number of events that are happening on each date for the next 14 days: SELECT DATE_FORMAT( ev.date, '%Y-%m-%d' ) as short_date, count(*) as date_count FROM event ev WHERE ev.date >= NOW() GROUP BY short_date ORDER BY ev.start_date ASC LIMIT 14 The result could be as follows: +------------+------------+ | short_date | date_count | +------------+------------+ | 2010-03-14 | 1 | | 2010-03-15 | 2 | | 2010-03-16 | 9 | | 2010-03-17 | 8 | | 2010-03-18 | 11 | | 2010-03-19 | 14 | | 2010-03-20 | 13 | | 2010-03-21 | 7 | | 2010-03-22 | 2 | | 2010-03-23 | 3 | | 2010-03-24 | 3 | | 2010-03-25 | 6 | | 2010-03-26 | 23 | | 2010-03-27 | 14 | +------------+------------+ 14 rows in set (0.06 sec) Let's say I want to dislay these events by date. At the same time I only want to display a maximum of 10 at a time. How would I do this? Somehow I need to limit this result by the SUM of the date_count field but I do not know how. Anybody run into this problem before? Any help would be appreciated. Thanks

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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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  • mysql NO_AUTO_VALUE_ON_ZERO problem

    - by every_answer_gets_a_point
    at least i think that is what the problem is. i am updating a mysql database through excel using an odbc like this: With rs .AddNew ' create a new record ' add values to each field in the record .Fields("datapath") = dpath .Fields("analysistime") = atime .Fields("reporttime") = rtime .Fields("lastcalib") = lcalib .Fields("analystname") = aname .Fields("reportname") = rname .Fields("batchstate") = "bstate" .Fields("instrument") = "NA" .Update ' stores the new record End With besides the fields above, i also have a primary key auto_increment field called rowid for some reason the only field that gets updated is instrument. none of the other fields get updated.. however, when i try to do the same updating on a table that has no ROWID auto_increment field, it works perfectly has anyone else experienced this kind of issue before?

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  • SQL query construction - separate data in a column into two columns

    - by Tommy
    I have a column that contains links. The problem is that the titles of the links are in the same column, so it looks like this: linktitle|-|linkurl I want link title and linkurl in separate columns. I've created a new column for the urls, so I'm looking for a way to extract them and update the linkurl column with them. Is there any clever way to construct a query that does this?

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  • Unable to get my master & details gridview to work.

    - by Javier
    I'm unable to get this to work. I'm very new at programming and would appreciate any help on this. <%@ Page Language="C#" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <script runat="server"> protected void Page_Load(object sender, EventArgs e) { } protected void DataGridSqlDataSource_Selecting(object sender, SqlDataSourceSelectingEventArgs e) { } </script> <html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server"> <title>Untitled Page</title> </head> <body> <form id="form1" runat="server"> <div> <asp:SqlDataSource ID="DataGrid2SqlDataSource" runat="server" ConnectionString="<%$ ConnectionStrings:JobPostings1ConnectionString %>" SelectCommand="SELECT [Jobs_PK], [Position_Title], [Educ_Level], [Grade], [JP_Description], [Job_Status], [Position_ID] FROM [Jobs]" FilterExpression="Jobs_PK='@Jobs_PK'"> <filterparameters> <asp:ControlParameter Name="Jobs_PK" ControlId="GridView1" PropertyName="SelectedValue" /> </filterparameters> </asp:SqlDataSource> <asp:SqlDataSource ID="DataGridSqlDataSource" runat="server" ConnectionString="<%$ ConnectionStrings:JobPostings1ConnectionString %>" SelectCommand="SELECT [Position_Title], [Jobs_PK] FROM [Jobs]" onselecting="DataGridSqlDataSource_Selecting"> </asp:SqlDataSource> <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" DataKeyNames="Jobs_PK" DataSourceID="DataGridSqlDataSource" AllowPaging="True" AutoGenerateSelectButton="True" SelectedIndex="0" Width="100px"> <Columns> <asp:BoundField DataField="Position_Title" HeaderText="Position_Title" SortExpression="Position_Title" /> <asp:BoundField DataField="Jobs_PK" HeaderText="Jobs_PK" InsertVisible="False" ReadOnly="True" SortExpression="Jobs_PK" /> </Columns> </asp:GridView> <br /> <asp:DetailsView ID="DetailsView1" runat="server" AutoGenerateRows="False" DataKeyNames="Jobs_PK" DataSourceID="DataGrid2SqlDataSource" Height="50px" Width="125px"> <Fields> <asp:BoundField DataField="Jobs_PK" HeaderText="Jobs_PK" InsertVisible="False" ReadOnly="True" SortExpression="Jobs_PK" /> <asp:BoundField DataField="Position_Title" HeaderText="Position_Title" SortExpression="Position_Title" /> <asp:BoundField DataField="Educ_Level" HeaderText="Educ_Level" SortExpression="Educ_Level" /> <asp:BoundField DataField="Grade" HeaderText="Grade" SortExpression="Grade" /> <asp:BoundField DataField="JP_Description" HeaderText="JP_Description" SortExpression="JP_Description" /> <asp:BoundField DataField="Job_Status" HeaderText="Job_Status" SortExpression="Job_Status" /> <asp:BoundField DataField="Position_ID" HeaderText="Position_ID" SortExpression="Position_ID" /> </Fields> </asp:DetailsView> </div> </form> </body> error message: Cannot perform '=' operation on System.Int32 and System.String. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.Data.EvaluateException: Cannot perform '=' operation on System.Int32 and System.String.

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  • MySQL: Query Cacheing (How do I use memcache?)

    - by Rachel
    I have an query like: SELECT id as OfferId FROM offers WHERE concat(partycode, connectioncode) = ? AND CURDATE() BETWEEN offer_start_date AND offer_end_date AND id IN ("121211, 123341,151512,5145626 "); Now I want to cache the results of this query using memcache and so my question is How can I cache an query using memcache. I am currently using CURDATE() which cannot be used if we want to implement caching and so how can I get current date functionality without using CURDATE() function ?

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  • Combine First, Middle Initial, Last name and Suffix in T-SQL (No extra spaces)

    - by Paul
    I'm trying not to reinvent the wheel here...I have these four fields [tbl_Contacts].[FirstName], [tbl_Contacts].[MiddleInitial], [tbl_Contacts].[LastName], [tbl_Contacts].[Suffix] And I want to create a FullName field in a view, but I can't have extra spaces if fields are blank...So I can't do FirstName + ' ' + MiddleInitial + ' ' + LastName + ' ' + Suffix...Because if there is no middle initial or suffix I'd have 2 extra spaces in the field. I think I need a Case statement, but I thought someone would have a handy method for this...Also, the middleinitial and suffix may be null.

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  • Redundancy in doing sum()

    - by Abhi
    table1 - id, time_stamp, value This table consists of 10 id's. Each id would be having a value for each hour in a day. So for 1 day, there would be 240 records in this table. table2 - id Table2 consists of a dynamically changing subset of id's present in table1. At a particular instance, the intention is to get sum(value) from table1, considering id's only in table2, grouping by each hour in that day, giving the summarized values a rank and repeating this each day. the query is at this stage: select time_stamp, sum(value), rank() over (partition by trunc(time_stamp) order by sum(value) desc) rn from table1 where exists (select t2.id from table2 t2 where id=t2.id) and time_stamp >= to_date('05/04/2010 00','dd/mm/yyyy hh24') and time_stamp <= to_date('25/04/2010 23','dd/mm/yyyy hh24') group by time_stamp order by time_stamp asc If the query is correct, can this be made more efficient, considering that, table1 will actually consist of thousand's of id's instead of 10 ? EDIT: I am using sum(value) 2 times in the query, which I am not able to get a workaround such that the sum() is done only once. Pls help on this

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  • SSRS run SQL/DataSet conditionally

    - by MikeTWebb
    Hello.... I have an SSRS report that contains several subreports. The user has the ability to select/deselect which subreports they want to produce using several Boolean parameters. If a subreport is deselected then it is not rendered by setting the Visibility property. However, the DataSet associated with the de-selected subreport still executes causing the execution time to take longer than expected. Is there any way to tell a dataset on a subreport or Tablix not to execute based on a Parameter selection? Thanks

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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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  • 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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  • How to repair "order by" after union of 2 selects from 1 tables

    - by 4e4el
    I have a dropDownList on my form, where i need to have union of values from 2 colums of table [ost]. Type of this columns is currency. I have russian version of access, default value of curency in "rur" and i need "uah". I need to change format and save "order by". I use this query: (SELECT distinct FORMAT([Sum1] ,'# ##0.00" uah.";-# ##0.00" uah."') FROM ost) Union (SELECT distinct FORMAT([Sum2],'# ##0.00" uah.";-# ##0.00" uah."') FROM ost) ORDER BY 1

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  • SQL queries to determine all values that would satisfy an arbitrary query

    - by jasterm007
    I'm trying to figure out how to efficiently run a set of queries that will provide a new table of all values that would return results for an arbitrary query. Say my table has a schema like: id name age city What is an efficient way to list all values that would return results for an arbitrary query, say "NOT city=X AND age BETWEEN Y and Z"? My naive approach for this would be to use a script and recurse through all possible combinations of {city, age, age} and see which SELECTs return more than 0 results, but that seems incredibly inefficient. I've also tried building large joins on {city, age, age} as well and basically using that table as an argument list to the query, but that quickly becomes an impossibility for queries on many columns. For simple conjunctive equality queries, i.e. "name=X and age=Y", this is much simpler, as I can do something like SELECT name, age, count(*) AS count FROM main GROUP BY name, age HAVING count > 0 But I'm having difficulty coming up with a general approach for anything more complicated than that. Any pointers in the right direction would be most helpful, thanks.

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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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