編輯

共用方式為

LookupRecord data block

  • 發行項

Applies to: Access 2013, Office 2013

A LookupRecord data block performs a set of actions on a specific record.

Note

The LookupRecord data block is available only in Data Macros.

Setting

The SetField action has the following arguments.

Argument

Required

Description

In

Yes

A string that identifies the record to operate on. The In argument can contain the name of the table, a select query, or a SQL statement.

NOTE: The specified record cannot include data stored in a linked table or ODBC data source.

Where Condition

No

A string expression used to restrict the range of data on which the LookupRecord data block is performed. For example, criteria are often equivalent to the WHERE clause in an SQL expression, without the word WHERE. If criteria are omitted, the LookupRecord data block operates on the entire domain specified by the In argument. Any field that is included in criteria must also be a field in In.

Alias

No

A string that provides an alternative name for the record specified by the In argument. Often used to shorten the table name for subsequent references to prevent possible ambiguous references. If Alias is not specified, the table or query name will be used as the alias.

Remarks

If the criteria specified by the In and Where Condition arguments returns more than one record, the LookupRecord data block will operate only on the first record. In the case that no records match the specified criteria, Access will skip over the set of actions contained within the LookupRecord block, as if it had been an If macro block expression that evaluated as false.

Example

The following example shows how to use the SetReturnVar action to return a value from a named data macro. A ReturnVar named CurrentServiceRequest is returned to the macro or Visual Basic for Applications (VBA) subroutine that called the named data macro.

Sample code provided by the Microsoft Access 2010 Programmer’s Reference.

    RunDataMacro
        Macro Name tblServiceRequests.dmGetCurrentServiceRequest
    
    Parameters
        prmAssignedTo =[ID]
    
    SetProperty
        Control Name txtCurrentSR
        Property Value
        Value =[ReturnVars]![CurrentServiceRequest]

The following example shows how to use the RaiseError action to cancel the Before Change data macro event. When the AssignedTo field is updated, a LookupRecord data block is used to determine whether the assigned technician is currently assigned to an open service request. If this is true, the Before Change event is cancelled and the record is not updated.

    /* Get the name of the technician  */
    Look Up A Record In tblTechnicians
        Where Condition =[tblTechnicians].[ID]=[tblServiceRequests].[AssignedTo]
    SetLocalVar
        Name TechName
        Expression [tblTechnicians].[FirstName] & " " & [tblTechnicians].[LastName]
    /* End LookUpRecord  */
    
    If Updated("AssignedTo") Then
        Look Up A Record In tblServiceRequests
            Where Condition SR.[AssignedTo]=tblServiceRequests[AssignedTo] And 
                SR.[ID]<>tblServiceRequests.[ID] And IsNull(SR.[ActualCompletionDate])
            Alias SR
            RaiseError
                Error Number 1234
                Error Description ="Cannot assign a request to the specified technician: " & [TechName]
    
    End If