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
orChina
.
Query 2
- Returns all rows where the country is either
Jamaica
orNew Zealand
.
Diese Übung ist Teil des Kurses
Improving Query Performance in SQL Server
Interaktive Übung
Versuche dich an dieser Übung, indem du diesen Beispielcode vervollständigst.
-- Query 1
SELECT *
FROM Cities
WHERE CountryCode = ___ -- Country code
OR CountryCode = ___ -- Country code