| Navigation: Language Reference > 13 - Built-in Functions >====== SETNULL (set file field null) ====== |    |
SETNULL(field)
SETNULL(file, field)
| SETNULL | Assigns null “value” to a field. |
| field | The label (including prefix) of a field in a FILE structure. This may be a GROUP or RECORD structure. |
| file | The label of a FILE. |
The SETNULL statement assigns a null “value” to a field in a FILE structure. If the field is a GROUP or RECORD structure, all component fields are set to null. Support for null “values” in a FILE is entirely dependent upon the file driver. The file must be opened before this statement is applied.
You can now pass a file as the first parameter to SETNULL. This allows you to pass references to fields (see the example below).
Example:
Customer FILE,DRIVER('Clarion'),PRE(Cus) !Declare customer file layout
AcctKey KEY(Cus:AcctNumber)
Record RECORD
AcctNumber LONG
OrderNumber LONG
Name STRING(20)
Addr STRING(20)
CSZ STRING(35)
END
END
Header FILE,DRIVER('Clarion'),PRE(Hea) !Declare header file layout
AcctKey KEY(Hea:AcctNumber)
OrderKey KEY(Hea:OrderNumber)
Record RECORD
AcctNumber LONG
OrderNumber LONG
ShipToName STRING(20)
ShipToAddr STRING(20)
ShipToCSZ STRING(35)
END
END
CODE
OPEN(Header)
OPEN(Customer)
SET(Hea:AcctKey)
LOOP
NEXT(Header)
IF ERRORCODE()
BREAK
END
Cus:AcctNumber = Hea:AcctNumber
GET(Customer,Cus:AcctKey) !Get Customer record
IF ERRORCODE()
CLEAR(Cus:Record)
END
IF NOT NULL(Hea:ShipToName) AND Hea:ShipToName = Cus:Name !Check ship-to address
SETNULL(Hea:ShipToName) !and assign null “values”
SETNULL(Hea:ShipToAddr) ! to ship-to address
SETNULL(Hea:ShipToCSZ)
END
PUT(Header) !Put Header record back
END
!Example Two ' Use of file parameter
SwapNullState PROCEDURE(File F, ANY var)
CODE
IF NULL(f, var)
SETNONULL(f, var)
ELSE
SETNULL(f, var)
END
See Also: