Update multiple records through custom script

Hi all,

I want to write code to update fullsyncdate attribute of UNSAccountB table for 1000 accounts at a time, something similar as below

Update UNSAccountB set FullSyncDate=DateTime.Now where cn in ('x','y'.....)

But am not getting any reference on how to do it. All I am getting is by updating one by one record. 

Below is my code block

Public Sub UpdateDaaSSyncInformationInUNSAccountBNew(ByVal userExistList As List(Of String),ByVal xproxyContext As String)
        logMessage("DaaS",xproxyContext+" >>CBA_DIF_UNSAccount_DaaS_Reconcile","UpdateDaaSSyncInformationInUNSAccountBNew","Entered method...")
        If(userExistList.Count>0) Then
        Dim whereClause As String=f.AndRelation(f.comparison("xproxyContext", xproxyContext,ValType.String), _
        'Load up a collection with all of the values we need
        Dim unsAccountBCollections As IColDbObject = Connection.CreateCol("UNSAccountB")
        unsAccountBCollections.Prototype.WhereClause = whereClause
        unsAccountBCollections.Prototype.Columns("UID_UNSAccountB").IsDisplayItem = True

        Dim uidUNSAcccountB As String
        Dim dbUnsAccountB As ISingleDbObject

' Do not want to iterate one by one account and update the property.

       For Each unsAccountB As IColElem In unsAccountBCollections
            uidUNSAcccountB = unsAccountB.GetValue("uidUNSAcccountB").ToString()
            dbUnsAccountB = Connection.CreateSingle("UNSAccountB", uidUNSAcccountB)
            dbUnsAccountB("FullSyncDate").NewValue = DateTime.Now.ToString()

End If
End Sub