DB/Reporting :: Updating Table With Results From Another One

I am trying to update one table with results from another table as such:
Table A (field, type) : Table B
ID (key) Integer : ID (key) Integer
ParentID Integer : IssueID Integer
Number String : ParentID Integer
: Number String

I need to construct and UPDATE statement that does:
Sets B.IssueID = A.ID When B.ParentID = A.ParentID AND B.Number = A.Number AND B.IssueID = 0

Here is what I have so far but it is producing an SQL syntax error (missing operator)
sqlStr = "UPDATE B SET IssueID = A.id FROM B JOIN A ON (B.ParentID = A.ParentID AND B.Number = A.Number) WHERE B.IssueID = 0

I have also tried
sqlStr = "UPDATE B SET IssueID = A.id FROM B, A WHERE (B.ParentID = A.ParentID AND B.Number = A.Number AND B.IssueID = 0)