Exercise: Use a CTE to show events containing this and that

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Category ==> SQL  (156 exercises)
Topic ==> Derived tables and CTEs  (8 exercises)
Level ==> Average difficulty
Courses ==> Introduction to SQL  /  Advanced SQL
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This exercise shows how you can use a CTE to make a complicated question simple, by dividing it into two or more parts.

First create a query to list out for each event id the positions (if any) of the words this and that:

Events with this and that

The first few events in the list - the last two columns give the position (if any) at which the words this and that can be found.

 

As an example, CHARINDEX('too','This too shall pass',1) would return 6, since the word too starts at the 6th letter of the given text (if you begin counting at the 1st character).

Now using this as a CTE, show the two events which contain both words in the right order (ie this followed by that).  You'll need to join your CTE to the events table, so that you can pick up on the event name and event date, and display them.

This and that events

The EventDetails column for these two events contains the words this and that, in this order.

 

Here's the sort of thing you'd have had to write without a CTE (showing how useful CTEs are!):

SELECT

e.EventName,e.EventDetails,

CHARINDEX('this',e.EventDetails,1) AS ThisPosition,

CHARINDEX('that',e.EventDetails,1) AS ThatPosition

FROM tblEvent AS e

WHERE

-- must contain both strings ...

CHARINDEX('this',e.EventDetails,1) > 0 and

CHARINDEX('that',e.EventDetails,1) > 0 and

-- ... in the right order

CHARINDEX('this',e.EventDetails,1)

CHARINDEX('that',e.EventDetails,1)

Save your query as This and that revisited, and close it down.

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