4D v13.4

COPY NAMED SELECTION

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4D v13.4
COPY NAMED SELECTION

COPY NAMED SELECTION 


 

COPY NAMED SELECTION ( {aTable ;} name ) 
Parameter Type   Description
aTable  Table in Table from which to copy selection, or Default table, if omitted
name  String in Name of the named selection to create

COPY NAMED SELECTION copies the current selection of aTable to the named selection name. The default table for the process is used if the optional table parameter is not specified. The parameter name contains a copy of the selection. The current selection and the current record of aTable for the process are not changed.

A named selection does not actually contain the records, but only an ordered list of references to records. Each reference to a record takes 4 bytes in memory. This means that when a selection is copied using the COPY NAMED SELECTION command, the amount of memory required is 4 bytes multiplied by the number of records in the selection. Since named selections reside in memory, you should have enough memory for the named selection as well as the current selection of the table in the process.

Use the CLEAR NAMED SELECTION command to free the memory used by name.

Example  

The following example allows you to check if there are other overdue invoices in the [People] table. The selection is sorted and then saved. We search for all records where invoices are due. Then we reuse the selection and clear the named selection in memory. Clearing the named selection in memory is optional, in case the database designer wants to keep the sorted selection for future use:

 ALL RECORDS([People])
  `Allow the user to sort the selection
 ORDER BY([People])
  ` Save the sorted selection as a named selection
 COPY NAMED SELECTION([People];"UserSort")
  ` Search for records where invoices are due
 QUERY([People];[People]InvoiceDue=True)
  ` If records are found
 If(Records in selection([People])>0)
  ` Alert the user
    ALERT("Yes, there are overdue invoices on table.")
 End if
  ` Reuse the sorted named selection
 USE NAMED SELECTION("UserSort")
  ` Remove the selection from memory
 CLEAR NAMED SELECTION("UserSort")

 
PROPERTIES 

Product: 4D
Theme: Named Selections
Number: 331

 
INDEX

Alphabetical list of commands

 
HISTORY 

Created: < 4D v6

 
SEE ALSO 

CLEAR NAMED SELECTION
CUT NAMED SELECTION
Identifiers
USE NAMED SELECTION