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**ClearKey ( **//key //[, //firstcomponent//] [, //lastcomponent//] [, //highvalue//] **)**

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| **ClearKey** | Clears or (re)initializes the specified range of key component fields. |
| //key// | The label of the KEY. |
| //firstcomponent// | A numeric constant, variable, EQUATE, or expression that indicates the first component to clear. If omitted, //firstcomponent //defaults to one (1). |
| //lastcomponent// | A numeric constant, variable, EQUATE, or expression that indicates the last component to clear. If omitted, //lastcomponent //defaults to twenty-two (22). |
| //highvalue// | An integer constant, variable, EQUATE, or expression that indicates whether to clear the components to zero (or spaces for string fields) or to their highest possible values. A value of one (1) applies the highest possible value; a value of zero (0) applies spaces for strings and zeros for numerics. If omitted, //highvalue //defaults to zero (0). |

The **ClearKey **method clears or (re)initializes the specified range of key component fields.

**Implementation: **ClearKey is useful for range limiting to the first instance of the first "free" key component. By retaining higher order key component values and clearing lower order key component values, you can fetch the first (or last) record that matches the retained higher order component values; for example, the first order (lower order key component) for a customer (higher order key component).

The value ClearKey assigns depends on three things: the data type of the component field (numeric or string), the sort direction of the component (ascending or descending), and the value of the //highvalue //parameter (True or False). The following table shows the values ClearKey assigns for each combination of data type, sort direction, and //highvalue//.

|  |  | __**Numeric Fields**__ | __**String Fields**__ |  |
| __**//highvalue//**__ | __**Ascending**__ | __**Descending**__ | __**Ascending**__ | __**Descending**__ |
| True (1) | High Values | zero | High Values | Spaces |
| False (0) | zero | High Values | spaces | High Values |

**Example:**

<code>
PROGRAM
INCLUDE('ABFILE.INC')              !declare FileManager class
MAP                                !program map
END
GlobalErrors ErrorClass             !declare GlobalErrors object
Access:Order CLASS(FileManager)     !derive Access:Order object
            END
 
Order    FILE,DRIVER('TOPSPEED'),PRE(ORD),CREATE,BINDABLE,THREAD
IDKey     KEY(Ord:Cust,Ord:ID,Ord:Date),NOCASE,OPT,PRIMARY
Record    RECORD,PRE()
Cust       LONG
ID         LONG
Date       LONG
         END
        END
CODE
!program code
!find first order for current customer by clearing all components except Ord:Cust
Access:Order.ClearKey( ORD:IDKey, 2 )     !clear Ord:ID and Ord:Date
Access:Order.Fetch()                      !get the next record by key
</code>