sql

How do I select a fixed number of rows for each group?

Here is some example data in a mysql table a b distance 15 44 250 94 31 250 30 41 250 6 1 250 95 18 250 72 84 500 14 23 500 55 24 500 95 8 500 59 25 500 40 73 500 65 85 500 32 50 500 31 39 500 22 25 500 37 11 750 98 39 750 15 57 750 9 22 750 14 44 750 69 22 750 62 50 750 89 35 750 67...

How do Relational Databases Work Under the Hood?

I've always been interested in how you can throw some SQL at at database, and it nearly instantaneously returns your results in an orderly manner without thinking about it as anything other than a black box. What is really going on? I'm pretty sure it has something to do with how values are laid out regularly in memory, similar to an a...

Can a Snapshot transaction fail and only partially commit in a TransactionScope?

Greetings I stumbled onto a problem today that seems sort of impossible to me, but its happening...I'm calling some database code in c# that looks something like this: using(var tran = MyDataLayer.Transaction()) { MyDataLayer.ExecSproc(new SprocTheFirst(arg1, arg2)); MyDataLayer.CallSomethingThatEventuallyDoesLinqToSql(arg1, argEtc);...

sql query to return items based on text and group ID

I am not sure how to best describe what I am trying to do (or search for it for that matter) but I am going to try. I have a pre-existing query (stored procedure) that returns items based on 3 specific ID's. What I want to do is to be able to reduce the results even further based upon a column within the results having the exact same st...

Is it possible to have a tableless select with multiple rows?

A SELECT without a FROM clause gets us a multiple columns without querying a table: SELECT 17+23, REPLACE('bannanna', 'nn', 'n'), RAND(), CURRENT_TIMESTAMP; How can we write a query that results in multiple rows without referring to a table? Basically, abuse SELECT to turn it into a data definition statement. The result could have a ...

SQL: Is there a more efficient way to calculate elapsed hours, minutes, seconds?

I'm using Computed Columns to provide me with the following information: Hours, Minutes, and Seconds between a Start DateTime and Finish DateTime (Where Minutes and Seconds are between 0 and 59 and Hours can be any value 0 or greater) Computed Column for Seconds: datediff(second,[Start],[Finish]) % 60 Computed Column for Minutes: f...

Is this select possible in sql?

Consider a table, Id columnA 1 a 2 b 3 c Select ColumnA from table gives the result as below, columnA a b c Is it possible to get ColumnA a,b,c ...

Finding rank of the student -Sql Compact

I have a table like this : Name Mar1 Mar2 Mar3 Total xxx 80 80 80 240 yyy 60 70 50 180 aaa 85 65 75 225 I wanted to find the rank of the student based on total. I using SQL Compact 3.5 . As we have rank() function in sql server do we have something with which we can find the students rank??? When I used "sele...

Show parts of the result of an SQL statement using PHP

I have an SQL query which returns a set of data (around 40-50 tuples). I would like to display the results 5 at a time on an HTML page using PHP. I already managed to have the right SELECT statement, but i am having problems to display the results 5 by 5 using a "more" button. Can you please help? Note that every time i call the query,...

Kohana 3 simple relations..

I'm trying to write a very simple cms (for learning purposes) in kohana 3 web framework. I have my db schemas and i want to map it to ORM but i have problems with relations. Schemas:articles and categories One article has one category. One category might has many articles of course. I think it is has_one relationship in article table....

Count problem in SQL when I want results from diffrent tabels

ALTER PROCEDURE GetProducts @CategoryID INT AS SELECT COUNT(tblReview.GroupID) AS ReviewCount, COUNT(tblComment.GroupID) AS CommentCount, Product.GroupID, MAX(Product.ProductID) AS ProductID, AVG(Product.Price) AS Price, MAX (Product.Year) AS Year, MAX (Product.Name) AS Name, AV...

Is there any way to optimize this LINQ where clause that searches for multiple keywords on multiple columns?

I have a LINQ query that searches for multiple keywords on multiple columns. The intention is that the user can search for multiple keywords and it will search for the keywords on every property in my Media entity. Here is a simplified example: var result = repository.GetAll<Media>().Where(x => x.Title.Contains("Apples") || x.Descri...

Should I use DATE and TIME as fields rather than DATETIME

I have a project on going for a TV guide, called mytvguide in the database - I use PHPMyAdmin. This is the structure for one table, which is called tvshow1: Field Type channel varchar(255) date date No airdate time No expiration time No ...

Database: Pipelined Functions

I am new to the concept of Pipeline Functions. I have some questions regarding From Database point of view: What actually is Pipeline function ? What is the advantage of using Pipeline Function ? What challenges are solved using Pipeline Function ? Are the any optimization advantages of using Pipeline Function ? Thanks. ...

Wildcards in T-SQL LIKE vs. ASP.net parameters

In my SQL statement I use wildcards. But when I try to select something, it never select something. While when I execute the query in Microsoft SQL Server Management Studio, it works fine. What am I doing wrong? Click handler protected void btnTitelAuteur_Click(object sender, EventArgs e) { cvalTitelAuteur.Enabled = true; cvalT...

Crystal Reports - Facilitating front/back printing

I have a single crystal report that usually ends up about 150 pages long. The single .rpt, through the use of clever grouping, actually includes records with little individual header and footer sections for each customer. Think of it as a sales report for 100 customers, each with their own section. Each customer section is 2 to 7 pages ...

PL/SQL How return all attributes in ROW

Hi I don't know how I can return all attributes with the RETURNING clause I want something like this: DECLARE v_user USER%ROWTYPE BEGIN INSERT INTO User VALUES (1,'Bill','QWERTY') RETURNING * INTO v_user; END; RETURNING * INTO gets an error , how can I replace * ? Have you any idea ? Thanks for yo...

Table/column names enclosed in square brackets, even though their names consist of legal characters

Square brackets allow you to use names for columns or aliases that contain characters not permitted for column names or aliases. a) I’ve noticed that lots of times table and column names are enclosed inside square brackets, even though their names consist of perfectly legal characters. Why is that? b) As far as I know, square brackets...

primary key datatype in sql server database

i see after installing the asp.net membership tables, they use the data type "uniqueidentifier" for all of the primary key fields. I have been using "int" data type and doing increment by one on inserts and declaring the column as IDENTITY. Is there any particular benefits to using the uniqueIdentifier data type compared to my current ...

what is a candidate row in SQL?

What is a candidate row when talking about Oracle and SQL? Using it in a sentence would be as such: "The candidate row is fetched from the table specified in the outer query." ...