title: Power Query - Creating a History table from a Part Change Register
body: <p>Hoping a Power Query Ninja might assist in solving this…</p>
  <p>Reference attachment, I have 2 tables the first [ChangeRegTBL] is a dynamic table (which currently is some 7500+ lines long) which appends changes we've implemented into a build/assembly line.  In certain instances, those part number changes are changed again into a new number once again…and in some instances 7-8 times!.</p>
  <p>What I'm after is a table (shown in ref attachment as [ ChangeHistTBL] ) which lists a history of every Part Old and what its superseded Part New is and if changed more than once a count and finally a history table summarising Date, Change Request and Part Detail.</p>
  <p>Now I've had multiple goes with many merges etc…but it's just messy, slow and certainly doesn't deal with a dynamic table.</p>
  <p>Trying to get to grips with the List. Accumulate function…as I feel the solution is within this</p>
  <p>Cheers</p>
  <p><a href="https://i.stack.imgur.com/o24XF.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/o24XF.jpg" alt="enter image description here" /></a></p>
  <p>Ok, I can't seem to add a workbook as an attachment, but can send this if required!</p>
  <p><a href="https://i.stack.imgur.com/jndaF.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/jndaF.jpg" alt="enter image description here" /></a></p>