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Indexes: how is it used in SQL SELECTs?
Message
From
20/12/2001 12:50:48
Hilmar Zonneveld
Independent Consultant
Cochabamba, Bolivia
 
 
To
20/12/2001 11:51:04
General information
Forum:
Visual FoxPro
Category:
Databases,Tables, Views, Indexing and SQL syntax
Miscellaneous
Thread ID:
00596834
Message ID:
00596875
Views:
18
>I have a table called myTable in a database called myData. myTable has a structural (primary) index called ID on field ID, and another (regular) index called LASTNAME on field LASTNAME. In this SQL statememt:
>SELECT * FROM myTable WHERE id='0125'
>is the ID index automatically used, or do I have to specifically specify that I'd like it to use the ID index?
>How about:
>SELECT * FROM myTable WHERE id>'0125' ORDER BY LASTNAME :
>both ID & LASTNAME index automatically used?
>Thanks all!

Any index that EXACTLY MATCHES the expression on the left side will be used to optimize the record fetching - whether this makes the query faster - or slower. I'm not sure about sorting.

Hilmar.
Difference in opinions hath cost many millions of lives: for instance, whether flesh be bread, or bread be flesh; whether whistling be a vice or a virtue; whether it be better to kiss a post, or throw it into the fire... (from Gulliver's Travels)
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