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PRIMARY( ) Function

  • Article

Returns true (.T.) if an index tag is a primary index tag; otherwise, returns false (.F.).

PRIMARY([nIndexNumber] [, nWorkArea | cTableAlias])

Return Values

Logical

Parameters

  • nIndexNumber
    Specifies the number of the index tag for which PRIMARY( ) returns the primary status. PRIMARY( ) returns the primary status in the following order as nIndexNumber increases from 1 to the total number of structural compound and independent compound index tags.

  1. Primary status for each tag in the structural compound index (if one is present) are returned first. The primary status is returned for the tags in the order the tags are created in the structural index.

  2. Primary status for each tag in any open, independent compound indexes are returned next. The primary status is returned for the tags in the order in which the tags are created in the independent compound indexes.

    If you omit nIndexNumber, PRIMARY( ) checks the master controlling index tag to see if it's a primary index tag. If there is no master controlling index tag, PRIMARY( ) returns false (.F.).

  • nWorkArea
    Specifies the work area of the index tag specified with nIndexNumber.

  • cTableAlias
    Specifies the work area of the index tag specified with nIndexNumber.

    If you omit nWorkArea and cTableAlias, PRIMARY( ) checks the index tag in the currently selected work area to see if it's a primary index tag.

Example

The following example opens the customer table in the database. FOR ... ENDFOR is used to create a loop in which the primary status of each index tag in the customer structural index is checked. The name of each structural index tag is displayed with its primary status.

CLOSE DATABASES
SET PATH TO (HOME(2) + 'Data\')   && Sets path to database
OPEN DATABASE testdata  && Open testdata database
USE Customer     && Open customer table

FOR nCount = 1 TO 254
   IF !EMPTY(TAG(nCount))  && Checks for tags in the index
   ? TAG(nCount)  && Display tag name
   ? PRIMARY(nCount)     && Display primary status
   ELSE
      EXIT  && Exit the loop when no more tags are found
   ENDIF
ENDFOR

See Also

ALTER TABLE – SQL | CANDIDATE( ) | CREATE TABLE – SQL | INDEX