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SQL | Looping exercise | Basic loop to count events for each year
This exercise is provided to allow potential course delegates to choose the correct Wise Owl Microsoft training course, and may not be reproduced in whole or in part in any format without the prior written consent of Wise Owl.
- Go into SQL Server Management Studio;
- Open the SQL file you've just unzipped (you can press CTRL + O to do this); then
- Execute this script.
This will generate the database that you'll need to use in order to do this exercise (note that the database and script are only to be used for exercises published on this website, and may not be reused or distributed in any form without the prior written permission of Wise Owl).
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The aim of this exercise is to create a query to show the number of events which occurred in each year that you have been alive, using a loop to run a separate select statement for each year:
The first few results for a Wise Owl born in 1981.
See below for details on how to do this.
The main parts of a loop are the starting point, counter, counter increment and end point - once you have these the rest of the loop is just the tasty filling:
-- create the counter, normally a variable
DECLARE @Counter INT =
-- create an end point to stop the loop
DECLARE @EndValue INT =
-- start the loop and set an end point
WHILE @Counter <=>=>
SET @Counter = @Counter + 1 --Increase the counter
Set the initial value of the counter to your year of birth, and loop until this reaches the current year (use year(GetDate())). You can then use the counter within your loop to filter a select statement counting the number of events.
Optionally save this as Going Loopy.sql and close it down.