VoDbEval Function |  |
Evaluate a code block for each record that matches a specified scope and/or condition.
Namespace: XSharp.RT
Assembly: XSharp.RT (in XSharp.RT.dll) Version: 2.21
SyntaxFUNCTION VoDbEval( cbExecute AS USUAL, cbForCondition AS USUAL, cbWhileCondition AS USUAL, nNext AS USUAL, nRecord AS USUAL, lRest AS LOGIC ) AS LOGIC
Parameters
- cbExecute
- Type: Usual
The code block to execute for each record that matches the scope and conditions. - cbForCondition
- Type: Usual
A code block that defines a condition that each record within the scope must meet in order to be processed. - cbWhileCondition
- Type: Usual
A code block that defines another condition that each record must meet in order to be processed. As soon as a record is encountered that causes the condition to fail, the operation terminates.
If no scope is specified, cbWhileCondition changes the default scope to lRest.
You define the scope using one of these three, mutually exclusive arguments.
The default is all records. - nNext
- Type: Usual
The number of records to process, starting at nRecord. Specify 0 to ignore this argument. - nRecord
- Type: Usual
A single record number to process. Specify 0 to ignore this argument. - lRest
- Type: Logic
TRUE processes only records from nStart to the end of the file. FALSE processes all records.
Return Value
Type: LogicTRUE if successful; otherwise, FALSE.
Remarks Tip |
|---|
| The nNext, nRecord, and lRest arguments are mutually exclusive. You should not pass all three of them. And if you pass the cbWhile argument then this also controls the scope behavior. |
This function, however, does not call the error handler and will not, therefore, produce a runtime error message or create an error object if it fails. Thus, it may be important to check the return value to determine if the function succeeded.
The global structure, StrucErrInfo, will contain needed information regarding any error that occurs. See DBEval() for more information.
Examples
This example uses VODBEval() to implement Count(), a function that counts the number of records in a work area matching a specified scope.
The scope is passed as an array to Count().
A set of constants defines the elements of the scope array:
The scope is passed as an array to Count().
A set of constants defines the elements of the scope array:
X#
1// Scope attribute constants 2DEFINE FOR_COND := 1 AS SHORTINT 3DEFINE WHILE_COND := 2 AS SHORTINT 4DEFINE NEXT_SCOPE := 3 AS SHORTINT 5DEFINE REC_SCOPE := 4 AS SHORTINT 6DEFINE REST_SCOPE := 5 AS SHORTINT 7DEFINE SCOPE_ELEMENTS := 5 AS SHORTINT 8FUNCTION Start() 9 // Create a scope and count records using it 10 LOCAL mySet[SCOPE_ELEMENTS] 11 LOCAL myCount AS LONGINT 12 USE customer NEW 13 mySet[FOR_COND] := {||customer = "Smith"} 14 mySet[WHILE_COND] := {||zip > "90000"} 15 mySet[REST_SCOPE] := FALSE 16 // Every record (ALL) 17 myCount := Count(mySet) 18 RETURN TRUE 19FUNCTION Count(aScope) AS LONGINT 20 LOCAL nCount := 0 AS LONGINT 21 VODBEval({|| nCount++},; 22 aScope[FOR_COND],; 23 aScope[WHILE_COND],; 24 aScope[NEXT_SCOPE],; 25 aScope[REC_SCOPE],; 26 aScope[REST_SCOPE]) 27 RETURN nCount
See Also