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  • SQL indexing on varchar

    - by alex
    I have a table whose columns are varchar(50) and a float - I need to (very quickly) look get the float associated with a given string. Even with indexing, this is rather slow. I know, however, that each string is associated with an integer, which I know at the time of lookup, so that each string maps to a unique integer, but each integer does not map to a unique string. One might think of it as a tree structure. Is there anything to be gained by adding this integer to the table, indexing on it, and using a query like SELECT floatval FROM mytable WHERE phrase=givenstring AND assoc=givenint? This is Postgres, and if you couldn't tell, I have very little experience with databases.

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  • Issue connecting to SQL Compact Edition on Windows Mobile 6 Emulator

    - by Chad
    I am developing an application for Windows Mobile 6 using an emulator. When I try to open the database connection to the SDF file it is throwing an exception that it is not able to connect or find the file. My questions are: Where on the mobile device is the SDF file supposed to be deployed? Does the SDF file get automatically deployed to the emulator when I build the project (like in then windows forms app) or do I have to do that manually? Any help would be appreciated.

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  • MS SQL Server BEGIN/END vs BEGIN TRANS/COMMIT/ROLLBACK

    - by Rich
    I have been trying to find info on the web about the differences between these statements, and it seems to me they are identical but I can't find confirmation of that or any kind of comparison between the two. What is the difference between doing this: BEGIN -- Some update, insert, set statements END and doing this BEGIN TRANS -- Some update, insert, set statements COMMIT TRANS ? Note that there is only the need to rollback in the case of some exception or timeout or other general failure, there would not be a conditional reason to rollback.

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  • SQL Design: representing a default value with overrides?

    - by Mark Harrison
    I need a sparse table which contains a set of "override" values for another table. I also need to specify the default value for the items overridden. For example, if the default value is 17, then foo,bar,baz will have the values 17,21,17: table "things" table "xvalue" name stuff name xval ---- ----- ---- ---- foo ... bar 21 bar ... baz ... If I don't care about a FK from xvalue.name - things.name, I could simply put a "DEFAULT" name: table "xvalue" name xval ---- ---- DEFAULT 17 bar 21 But I like having a FK. I could have a separate default table, but it seems odd to have 2x the number of tables. table "xvalue_default" xval ---- 17 table "xvalue" name xval ---- ---- bar 21 I could have a "defaults table" tablename attributename defaultvalue xvalue xval 17 but then I run into type issues on defaultvalue. My operations guys prefer as compact a representation as possible, so they can most easily see the "diff" or deviations from the default. What's the best way to represent this, including the default value? This will be for Oracle 10.2 if that makes a difference.

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  • Clustered index - multi-part vs single-part index and effects of inserts/deletes

    - by Anssssss
    This question is about what happens with the reorganizing of data in a clustered index when an insert is done. I assume that it should be more expensive to do inserts on a table which has a clustered index than one that does not because reorganizing the data in a clustered index involves changing the physical layout of the data on the disk. I'm not sure how to phrase my question except through an example I came across at work. Assume there is a table (Junk) and there are two queries that are done on the table, the first query searches by Name and the second query searches by Name and Something. As I'm working on the database I discovered that the table has been created with two indexes, one to support each query, like so: --drop table Junk1 CREATE TABLE Junk1 ( Name char(5), Something char(5), WhoCares int ) CREATE CLUSTERED INDEX IX_Name ON Junk1 ( Name ) CREATE NONCLUSTERED INDEX IX_Name_Something ON Junk1 ( Name, Something ) Now when I looked at the two indexes, it seems that IX_Name is redundant since IX_Name_Something can be used by any query that desires to search by Name. So I would eliminate IX_Name and make IX_Name_Something the clustered index instead: --drop table Junk2 CREATE TABLE Junk2 ( Name char(5), Something char(5), WhoCares int ) CREATE CLUSTERED INDEX IX_Name_Something ON Junk2 ( Name, Something ) Someone suggested that the first indexing scheme should be kept since it would result in more efficient inserts/deletes (assume that there is no need to worry about updates for Name and Something). Would that make sense? I think the second indexing method would be better since it means one less index needs to be maintained. I would appreciate any insight into this specific example or directing me to more info on maintenance of clustered indexes.

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  • "The data types text and nvarchar are incompatible in the equal to operator" in SQL Query

    - by kenom
    Why i get this error: The data types text and nvarchar are incompatible in the equal to operator. The field of "username" in database is text type... This is my soruce: <%@ Control Language="C#" AutoEventWireup="true" CodeFile="my_answers.ascx.cs" Inherits="kontrole_login_my_answers" %> <div style=" margin-top:-1280px; float:left;"> <p></p> <div id="question"> Add question </div> </div> <asp:GridView ID="GridView1" runat="server" DataSourceID="SqlDataSource1" > </asp:GridView> <asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:estudent_piooConnectionString %>" SelectCommand="SELECT * FROM [question] WHERE ([username] = @fafa)"> <SelectParameters> <asp:QueryStringParameter Name="fafa" QueryStringField="user" Type="String"/> </SelectParameters> </asp:SqlDataSource>

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  • Problem with Full text Searching

    - by devendra
    I am searching in resumes weather the word is exist or not i am using the below query Case1: select top(10) c_resume_text from sntbl_candidates where contains(c_resume_text,'"a/dm"') in the above example only it is not working properly .It showing resumes even though there is no text like that. In Messages i am getting the following message. Informational: The full-text search condition contained noise word(s). if i try with Case 2: select top(10) c_resume_text from sntbl_candidates where contains(c_resume_text,'"a/d') i am getting proper results in case 2 can any one suggest me what to do. Thanks

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  • When should I open and close a connection to SQL Server

    - by Martin
    I have a simple static class with a few methods in it. Each of those methods open a SqlConnection, query the database and close the connection. This way, I am sure that I always close the connection to the database, but on the other hand, I don't like to always open and close connection. Below is an example of what my methods look like. public static void AddSomething(string something) { using (SqlConnection connection = new SqlConnection("...")) { connection.Open(); // ... connection.Close(); } } Considering that the methods are inside a static class, should I have a static member containing a single SqlConnection? How and when should I drop it? What are the best practices?

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  • SQL Group By equivalent

    - by MikeB
    Pretend I have a cupcake_rating table: id | cupcake | delicious_rating -------------------------------------------- 1 | Strawberry | Super Delicious 2 | Strawberry | Mouth Heaven 3 | Blueberry | Godly 4 | Blueberry | Super Delicious I want to find all the cupcakes that have a 'Super Delicious' AND 'Mouth Heaven' rating. I feel like this is easily achievable using a group by clause and maybe a having. I was thinking: select distinct(cupcake) from cupcake_rating group by cupcake having delicious_rating in ('Super Delicious', 'Mouth Heaven') I know I can't have two separate AND statements. I was able to achieve my goal using: select distinct(cupcake) from cupcake_rating where cupcake in ( select cupcake from cupcake_rating where delicious_rating = 'Super Delicious' ) and cupcake in ( select cupcake from cupcake_rating where delicious_rating = 'Mouth Heaven' ) This will not be satisfactory because once I add a third type of rating I am looking for, the query will take hours (there are a lot of cupcake ratings).

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  • Different execution plan for similar queries

    - by Graham Clements
    I am running two very similar update queries but for a reason unknown to me they are using completely different execution plans. Normally this wouldn't be a problem but they are both updating exactly the same amount of rows but one is using an execution plan that is far inferior to the other, 4 secs vs 2 mins, when scaled up this is causing me a massive problem. The only difference between the two queries is one is using the column CLI and the other DLI. These columns are exactly the same datatype, and are both indexed exactly the same, but for the DLI query execution plan, the index is not used. Any help as to why this is happening is much appreciated. -- Query 1 UPDATE a SET DestKey = ( SELECT TOP 1 b.PrefixKey FROM refPrefixDetail AS b WHERE a.DLI LIKE b.Prefix + '%' ORDER BY len(b.Prefix) DESC ) FROM CallData AS a -- Query 2 UPDATE a SET DestKey = ( SELECT TOP 1 b.PrefixKey FROM refPrefixDetail b WHERE a.CLI LIKE b.Prefix + '%' ORDER BY len(b.Prefix) DESC ) FROM CallData AS a

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  • SQL Server last called stored procedures with parameters

    - by Teoman shipahi
    I am using ASP.NET environment. Is it possible to track last N number of stored procedures called with parameters info? I see in this article "Recently executed stored procedures"; http://sqlfool.com/2009/08/find-recently-executed-stored-procedures/ But I need input parameters also. If not what can be the best way to track it? For example, adding an insert statement to a information table for every single procedure beginning? Or is there any better solution for this?

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  • MySQL/SQL: Update with correlated subquery from the updated table itself

    - by Roee Adler
    I have a generic question that I will try to explain using an example. Say I have a table with the fields: "id", "name", "category", "appearances" and "ratio" The idea is that I have several items, each related to a single category and "appears" several times. The ratio field should include the percentage of each item's appearances out of the total number of appearances of items in the category. In pseudo-code what I need is the following: For each category find the total sum of appearances for items related to it. For example it can be done with (select sum("appearances") from table group by category) For each item set the ratio value as the item's appearances divided by the sum found for the category above Now I'm trying to achieve this with a single update query, but can't seem to do it. What I thought I should do is: update Table T set T.ratio = T.appearances / ( select sum(S.appearances) from Table S where S.id = T.id ) But MySQL does not accept the alias T in the update column, and I did not find other ways of achieving this. Any ideas?

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  • SQL Reset Identity ID in already populated table

    - by rockinthesixstring
    hey all. I have a table in my DB that has about a thousand records in it. I would like to reset the identity column so that all of the ID's are sequential again. I was looking at this but I'm ASSuming that it only works on an empty table Current Table ID | Name 1 Joe 2 Phil 5 Jan 88 Rob Desired Table ID | Name 1 Joe 2 Phil 3 Jan 4 Rob Thanks in advance

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  • Need help configuring SQL Server CE connections string in Fluent NHibernate

    - by Yoav
    Hi, I'm trying to return a session factory using this code: return Fluently.Configure() .Database(MsSqlCeConfiguration.Standard.ShowSql().ConnectionString(path)) .Mappings(m => m.FluentMappings.AddFromAssemblyOf<Project>()) .BuildSessionFactory(); Path is the full path to an .sdf file. And get this exception: System.ArgumentException: Format of the initialization string does not conform to specification starting at index 0. at System.Data.SqlServerCe.ConStringUtil.GetKeyValuePair(Char[] connectionString, Int32 currentPosition, String& key, Char[] valuebuf, Int32& vallength, Boolean& isempty) What am I doing wrong?

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  • SQL using sum to count results of multiple subqueries

    - by asdas
    I have a table with 2 columns: integer and var char. I am given only the integer values but need to do work on the var char (string) values. Given an integer, and a list of other integers (no overlap), I want to find the string for that single integer. Then I want to take that string and do the INSTR command with that string, and all the other strings for all the other integers. Then I want the sum of all the INSTR so the result is one number. So lets say I have int x, and list y=[y0, y1, y2]. I want to do 3 INSTR commands like SUM(INSTR(string for x, string for y0), INSTR(string for x, string for y1), INSTR(string for x, string for y2)) I think im going in the wrong direction, this is what I have. Im not good with sub queries. SELECT SUM ( SELECT INSTR ( SELECT string FROM pages WHERE int=? LIMIT 1, ( SELECT string FROM pages WHERE id=? OR id=? OR id=? LIMIT 3 ) ) )

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  • How can I limit the number of connections to an mssql server from my tomcat deployed java applicatio

    - by CJ
    Hi, I have an application that is deployed on tomcat on server A and sends queries to a huge variety of mssql databases on an server B. I am concerned that my application could overload this mssql database server and would like some way to preventing it making requests to connect to any database on that server if some arbitrary number of connections were already in existence and unclosed. I am looking at using connection pooling but am under the impression that this will only pool connections to a specific database on the mssql server, I want to control the total of these combined connections that will occur to many different databases (incidentally I can only find out the names of individual db's dynamically as they change day to day). Will connection pooling take care of this for me, are am I looking at this from the wrong perspective? I have no access to the configuration of the mssql server. Links to tutorials or working examples of your suggested solution are most welcome! Thanks, Caroline

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  • Using AVG() in Oracle SQL

    - by Viet Anh
    I have a table named Student as followed: CREATE TABLE "STUDENT" ( "ID" NUMBER(*,0), "NAME" VARCHAR2(20), "AGE" NUMBER(*,0), "CITY" VARCHAR2(20), PRIMARY KEY ("ID") ENABLE ) I am trying to get all the records of the students having a larger age than the average age. This is what I tried: SELECT * FROM student WHERE age > AVG(age) and SELECT * FROM student HAVING age > AVG(age) Both ways did not work!

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  • Separating date ranges into separate segments in SQL

    - by Richard
    I have a table containing 2 date fields and an identifier (id, fromdate and todate) These dates overlap in any and every possible way. I need to produce a list of segments each with a start and end date describing the separate segments in that list. For example: id, FromDate ToDate 1, 1944-12-11, 1944-12-31 2, 1945-01-01, 1945-12-31 3, 1945-01-01, 1945-06-30 4, 1945-12-31, 1946-05-01 5, 1944-12-17, 1946-03-30 Should produce all the segments of all the overlaps: 1, 1944-12-11, 1944-12-16 1, 1944-12-17, 1944-12-31 5, 1944-12-17, 1944-12-31 2, 1945-01-01, 1945-06-30 3, 1945-01-01, 1945-06-30 5, 1945-01-01, 1945-06-30 2, 1945-07-01, 1945-12-09 5, 1945-07-01, 1945-12-09 2, 1945-12-10, 1945-12-31 4, 1945-12-10, 1945-12-31 5, 1945-12-10, 1945-12-31 4, 1946-01-01, 1946-03-30 5, 1946-01-01, 1946-03-30 4, 1946-04-01, 1946-05-01 Or perhaps a diagram might help INPUT 1 <----> 2 <-----------> 3 <-----> 4 <----------> 5 <-----------------> OUTPUT 1 <-> 1 <-> 5 <-> 2 <-----> 3 <-----> 5 <-----> 2 <-> 5 <-> 2 <-> 4 <-> 5 <-> 4 <-> 5 <-> 4 <----> Please help

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  • UNIQUE CONSTRAINT on a column from foreign table in MSSQL2008

    - by bodziec
    Hi, I have two tables: create table [dbo].[Main] ( [ID] [int] identity(1,1) primary key not null, [Sign] [char](1) not null ) create table [dbo].[Names] ( [ID_Main][int] primary key not null, [Name][nvarchar](128) not null, constraint [FK_Main_Users] foreign key ([ID_Main]) references [dbo].[Main]([ID]), constraint [CK_Name] unique ([Name], [Sign]) ) The problem is with the second constraint CK_Name Is there a way to make a constraint target column from a foreign table?

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  • Guid Primary /Foreign Key dilemma SQL Server

    - by Xience
    Hi guys, I am faced with the dilemma of changing my primary keys from int identities to Guid. I'll put my problem straight up. It's a typical Retail management app, with POS and back office functionality. Has about 100 tables. The database synchronizes with other databases and receives/ sends new data. Most tables don't have frequent inserts, updates or select statements executing on them. However, some do have frequent inserts and selects on them, eg. products and orders tables. Some tables have upto 4 foreign keys in them. If i changed my primary keys from 'int' to 'Guid', would there be a performance issue when inserting or querying data from tables that have many foreign keys. I know people have said that indexes will be fragmented and 16 bytes is an issue. Space wouldn't be an issue in my case and apparently index fragmentation can also be taken care of using 'NEWSEQUENTIALID()' function. Can someone tell me, from there experience, if Guid will be problematic in tables with many foreign keys. I'll be much appreciative of your thoughts on it...

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  • Question About DateCreated and DateModified Columns - SQL Server

    - by user311509
    CREATE TABLE Customer ( customerID int identity (500,20) CONSTRAINT . . dateCreated datetime DEFAULT GetDate() NOT NULL, dateModified datetime DEFAULT GetDate() NOT NULL ); When i insert a record, dateCreated and dateModified gets set to default date/time. When i update/modify the record, dateModified and dateCreated remains as is? What should i do? Obviously, i need to dateCreated value to remain as was inserted the first time and dateModified keeps changing when a change/modification occurs in the record fields. In other words, can you please write a sample quick trigger? I don't know much yet...

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