Exercise: Basic dynamic SQL to pass in table name

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.

The answer to the exercise will be included and explained if you attend the course listed below!

Category ==> SQL  (192 exercises)
Topic ==> Dynamic SQL  (4 exercises)
Level ==> Relatively easy
Course ==> Advanced SQL
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). Once you've done this:
  1. Go into SQL Server Management Studio;
  2. Open the SQL file you've just unzipped (you can press CTRL + O to do this); then
  3. 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).

You need a minimum screen resolution of about 700 pixels width to see our exercises. This is because they contain diagrams and tables which would not be viewable easily on a mobile phone or small laptop. Please use a larger tablet, notebook or desktop computer, or change your screen resolution settings.

The aim of this exercise is to be able to pass different table names to a select statement, to show different sets of rows.  First create a stored procedure which selects everything from the table tblEvent:

Something

The first few events.

Now add a varchar(max) parameter called @TableName to hold the name of the table from which you want to extract data, and use its value in place of tblEvent in the FROM clause. Sadly this doesn't work and results in an error:

Parameters Dynamic SQL

It takes a while to accept that this can't work!

Declare a varchar(max) variable called @SQL, and set it equal to the SQL script up to the FROM keyword, then add your parameter value on the end:

DECLARE @SQL VARCHAR(MAX) =

'SELECT * FROM ' +

@TableName

Then finally either use EXEC (@SQL) or Exec SP_SQLEXEC @SQL at the bottom of the stored procedure to run the select statement contained in your variable.

Now try running the stored procedure:

Dynamic SQL in action

Try passing in each of the tblEvent, tblCountry and tblContinent table names.

Optionally save this as Turning the table.sql, and close it down.

This page has 0 threads Add post