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Modify an index properties

Posted on 2000-04-11
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Last Modified: 2008-03-06
Hi there, i want to modify the "indexed" property of a field. I want to be able to do that in a function with code. I know how to change a field type and size but i don't see how modify this property from yes(no duplicates) with yes(duplicates OK).
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Question by:tusken
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by:paasky
Comment Utility
Hello tusken,

Here's Drop-and-create function to change table index:

Public Function AlterIndex(IndexName As String, TableName As String, FieldNames As String, Optional Unique As Boolean)
    CurrentDb.Execute ("DROP INDEX " & IndexName & " ON " & TableName)
    CurrentDb.Execute ("CREATE " & IIf(Unique, "UNIQUE", "") & " INDEX " & IndexName & " ON " & TableName & "(" & FieldNames & ")")
End Function

Hope this helps,
Paasky
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Expert Comment

by:davereynolds
Comment Utility
Hi tusken,
There seems to quite a bit of info about this in the Help section (TableDefs~Indexes). I've pasted an example of setting the Unique property.
This example sets the Unique property of a new Index object to True, and appends the Index to the Indexes collection of the Employees table. It then enumerates the Indexes collection of the TableDef and the Properties collection of each Index. The new Index will only allow one record with a particular combination of Country, LastName, and FirstName in the TableDef.

Sub UniqueX()

      Dim dbsNorthwind As Database
      Dim tdfEmployees As TableDef
      Dim idxNew As Index
      Dim idxLoop As Index
      Dim prpLoop As Property

      Set dbsNorthwind = OpenDatabase("Northwind.mdb")
      Set tdfEmployees = dbsNorthwind!Employees

      With tdfEmployees
            ' Create and append new Index object to the Indexes
            ' collection of the Employees table.
            Set idxNew = .CreateIndex("NewIndex")

            With idxNew
                  .Fields.Append .CreateField("Country")

..Fields.Append .CreateField("LastName")
                  .Fields.Append .CreateField("FirstName")
                  .Unique = True
            End With

            .Indexes.Append idxNew
            .Indexes.Refresh

            Debug.Print .Indexes.Count & " Indexes in " & _
                  .Name & " TableDef"

            ' Enumerate Indexes collection of Employees table.
            For Each idxLoop In .Indexes
                  Debug.Print "    " & idxLoop.Name

                  ' Enumerate Properties collection of each Index
                  ' object.

For Each prpLoop In idxLoop.Properties
                        Debug.Print "        " & prpLoop.Name & _
                              " = " & IIf(prpLoop = "", "[empty]", prpLoop)
                  Next prpLoop

            Next idxLoop

            ' Delete new Index because this is a demonstration.
            .Indexes.Delete idxNew.Name
      End With

      dbsNorthwind.Close

End Sub

HTH
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paasky earned 100 total points
Comment Utility
Here's same with Objects:

Public Function AlterIndex(IndexName As String, TableName As String, FieldNames As String, Optional Unique As Boolean)
Dim MyIndex As Index

    CurrentDb.TableDefs(TableName).Indexes.Delete IndexName
    Set MyIndex = CurrentDb.TableDefs(TableName).CreateIndex(IndexName)
    With MyIndex
        .Fields = FieldNames
        .Unique = Unique
        .Primary = False
        .IgnoreNulls = False
        .Required = False
    End With
    CurrentDb.TableDefs(TableName).Indexes.Append MyIndex
   
End Function

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Expert Comment

by:paasky
Comment Utility
There's a little difference in parameter passing if the index contains more than one field.

With first example use commas (,) and second semicolon (;) to separate different fields.

? AlterIndex ("Test","Table1","Field1,Field2",False)

? AlterIndex ("Test","Table1","Field1;Field2",False)

Paasky
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Author Comment

by:tusken
Comment Utility
Hey paasky, you've remember i like the object version better!!!! ;-)
One thing, i do the change with the field, the code goes by without an error but i does not change anything....

My table have 2 Primary key cNoCSST and noDossier, does that change something??? I just want to change the indexed property of the field cNoCSST. If i want to pass from (no duplicate) to (duplicate OK) i just have to set the unique property to false, Right??



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Expert Comment

by:paasky
Comment Utility
yes tusken, I remembered you love objects :-)

This should work assuming your cNoCSST field index name is same as field name (check that in Indexes window in table design view -> View|Indexes)

? AlterIndex ("cNoCSST","YourTableName","cNoCSST",False)

Your two field PK is probably named as "PrimaryKey".

regards,
Paasky
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LVL 10

Expert Comment

by:paasky
Comment Utility
(Access names the index same name as field by default)
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Author Comment

by:tusken
Comment Utility
Hey paasky, you've remember i like the object version better!!!! ;-)
One thing, i do the change with the field, the code goes by without an error but i does not change anything....

My table have 2 Primary key cNoCSST and noDossier, does that change something??? I just want to change the indexed property of the field cNoCSST. If i want to pass from (no duplicate) to (duplicate OK) i just have to set the unique property to false, Right??



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Expert Comment

by:paasky
Comment Utility
Unique = False -> Duplicates OK
Unique = True -> Duplicates are not allowed
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Author Comment

by:tusken
Comment Utility
Hey passky!
i have to go for today, i'll check that tomorrow and let you know how it goes...

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Author Comment

by:tusken
Comment Utility
Thanks!
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Expert Comment

by:paasky
Comment Utility
Happy to help you tusken.

Best regards,
Paasky
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