Sanjay, my colleague is an avid programmer and excel enthusiast. In his spare time he wrote a small VBA macro to solve Sudoku. Sudoku is a very famous number based puzzle with a 9×9 grid of cells. Each of the 9 rows, columns and 3×3 blocks should be filled in such a way that they have all the numbers from 1 to 9. Sudoku is a very effective way to keep your brain cells ticking. I am a huge sudoku fan and I solve sudoku whenever I have few minutes to kill. So naturally I jumped with joy when I saw Sanjay’s excel macro for solving sudoku. He is kind enough to let me share this with all of you.
Click here to download the sudoku solver workbook. It has macros, so enable them when you download the file.
The file is unlocked, so if you are curious, go around and poke the code.
And if you are interested in writing your own sudoku solver, here is a basic algorithm:
- While Sudoku is not solved,
- Check if any row, column or 3×3 block has ‘n’ cells such that, (n>1)
- All possible values in those ‘n’ cells are exactly ‘n’ unique values
- For each block of such cells,
- Remove the occurrences of the ‘n’ unique values from remaining cell’s possible’s list in that row / column / 3×3 grid
- Check if any cell has more than one possible value. If so, Sudoku is not solved.
- Check if any row, column or 3×3 block has ‘n’ cells such that, (n>1)
- Do While
One Response to “SQL vs. Power Query – The Ultimate Comparison”
Enjoyed your SQL / Power Query podcast (A LOT). I've used SQL a little longer than Chandoo. Power Query not so much.
Today I still use SQL & VBA for my "go to" applications. While I don't pull billions of rows, I do pull millions. I agree with Chandoo about Power Query (PQ) lack of performance. I've tried to benchmark PQ to SQL and I find that a well written SQL will work much faster. Like mentioned in the podcast, my similar conclusion is that SQL is doing the filtering on the server while PQ is pulling data into the local computer and then filtering the data. I've heard about PQ query folding but I still prefer SQL.
My typical excel application will use SQL to pull data from an Enterprise DB. I load data into Structured Tables and/or Excel Power Pivot (especially if there's lot of data).
I like to have a Control Worksheet to enter parameters, display error messages and have user buttons to execute VBA. I use VBA to build/edit parameters used in the SQL. Sometimes I use parameter-based SQL. Sometimes I create a custom SQL String in a hidden worksheet that I then pull into VBA code (these may build a string of comma separated values that's used with a SQL include). Another SQL trick I like to do is tag my data with a YY-MM, YY-QTR, or YY-Week field constructed form a Transaction Date.
In an application, I like to create a dashboard(s) that may contain hyperlinks that allow the end-user to drill into data. Sometimes the hyperlink will point to worksheet and sometimes to a supporting workbook. In some cases, I use a double click VBA Macro that will pull additional data and direct the user to a supplemental worksheet or pivot table.
In recent years I like Dynamic Formulas & Lambda Functions. I find this preferable to pivot tales and slicers. I like to use a Lambda in conjunction with a cube formula to pull data from a power pivot data model. I.E. a Lambda using a cube formula to aggregate Accounting Data by a general ledger account and financial period. Rather than present info in a power pivot table, you can use this combination to easily build financial reports in a format that's familiar to Accounting Professionals.
One thing that PQ does very well is consolidating data from separate files. In the old days this was always a pain.
I've found that using SQL can be very trying (even for someone with experience). It's largely an iterative process. Start simple then use Xlookup (old days Match/Index). Once you get the relationships correct you can then use SQL joins to construct a well behaved SQL statement.
Most professional enterprise systems offer a schema that's very valuable for constructing SQL statements. For any given enterprise system there's often a community of users that will share SQL. I.E. MS Great Plains was a great source (but I haven't used them in years).
Hope this long reply has value - keep up the good work.