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Question on table indexes
Message
Information générale
Forum:
Visual FoxPro
Catégorie:
Base de données, Tables, Vues, Index et syntaxe SQL
Divers
Thread ID:
00306942
Message ID:
00306956
Vues:
30
Over 99% of my indexes are on 1 field. Keep in mind that if you have an index on single fields, the following where clause is Rushmore optimizable if all 3 fields are indexed:

... where Field1 = value1 and Field2 = value2 and Field3 = value3 ...

If you have an index on upper(lastname), the following is optimizable:

... where upper(lastname) = "SMITH" ...

As for a SEEK, you can Seek on the current single-field index, then use locate:

LOCATE FOR FIELD2 = VALUE2 WHILE FIELD1 = The_Value_Seeked

>The DBMS language I had used for DOS had a limitation on the number of indexes we could have so I am very accustomed to making compound indexes involving many fields.
>
>As I am becoming more familiar with the way VFP and Rushmore works I am beginning to wonder if it isn't better to create most of my indexes based on one field.
>
>The only down side I see to doing this is that I wouldn't be able to use seek statements if my search criteria involves more than one field. But then I guess I could use a locate for with multiple indexes.
>
>I know there would be exceptions to the rules where I would want more than one field in an index...But, I am just curious on how some of you set up your indexes.
>
>Thanks for your time,
>Paul
Mark McCasland
Midlothian, TX USA
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