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No Functions on Left Side of Operator
Don’t use functions on a column in the where clause
You will get an index scan instead of a seek, take a look these two queries. The first query uses a function while the second does not and is therefore sargable
- SELECT * FROM Orders WHERE LEFT(CustomerID,1) ='V'
- SELECT * FROM Orders WHERE CustomerID LIKE 'V%'
Here is the execution plan
Contributed by: --SQLDenis 15:24, 31 May 2008 (GMT)
Section Query Optimization