SQL | Archived exercise | Fn to count trainer ids

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.

You can learn how to do this exercise on the relevant Wise Owl classroom training course (sadly for the moment only in the UK).

Software ==> SQL  (198 exercises)
Version ==> Any version of SQL Server
Topic ==> Archived  (70 exercises)
Level ==> Average difficulty
Before you can do this exercise, you'll need to download and unzip this file (if you have any problems doing this, click here for help).

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If you haven't already done so, run the stored procedure in the above folder to generate a database of training courses and delegates.

Each row in the tblSchedule table contains a column called TrainerIds, giving details of who is assigned to train on the course:

SQL exercise - Avoiding scalar functions (image 1)

Scheduled course 1, for example, has trainers number 21 and 93 assigned to it

We will create a function called fnCountIds to count how many trainers there are assigned to each course (note that exactly the same function could also count how many resources are assigned).  The following code excerpt contains an idea to help you do this:

SQL exercise - Avoiding scalar functions (image 2)

Count the number of trainers by seeing how long the string of ids is with and without its commas, and then taking the difference between these two numbers

Incorporate your function in a query to count the number of trainers assigned to a course:

SQL exercise - Avoiding scalar functions (image 3)

The first few rows of the final query, sorted by course start date

Optionally, save the code to generate your function as Count trainers.sql, then close it down.

You can unzip this file to see the answers to this exercise, although please remember this is for your personal use only.
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