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  3. Improving Query Performance in SQL Server

Exercise

Clustered index

Clustered indexes can be added to tables to speed up search operations in queries. You have two copies of the Cities table from the Earthquakes database: one copy has a clustered index on the CountryCode column. The other is not indexed.

You have a query on each table with a different filter condition:

Query 1

  • Returns all rows where the country is either Russia or China.

Query 2

  • Returns all rows where the country is either Jamaica or New Zealand.

Instructions 1/3

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  • Add the two country codes to the filter condition for Query 1.