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**SETNULL(**//field//**)**

**SETNULL(**//file, field//**)**

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| **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:**

[[null  return null file field .htm|NULL]]

[[setnonull  set file field non null .htm|SETNONNULL]]

[[getnulls get the null state of a table .htm|GETNULLS]]

[[setnulls set the null state of columns .htm|SETNULLS]]