Geert JM Vanderkelen

Update 2010-08-27: Comments indicated that what I did here is not the best solution. Like noted in my original post, a set would be better in this case. I eventually used set(r).issubset(set(l)). Marius also pointed out to set(r) <= set(l), but I like the issubset one more.

I wanted to check if every element of one list or tuple is part of another one using Python. A set has the issubset()-method, but I couldn't find anything build-in for a tuple. It was, however, rather quickly done:

>>> r = (1,2)
>>> l = (3,4,1,5,2)
>>> False not in [ e in l for e in r ]
True
>>> r = (1,9)
>>> False not in [ e in l for e in r ]
False

Why I'm posting this? I just found it cute code, somehow.

Playing chess within MySQL? Over the network? In the .. cloud? Yes!

This is a follow-up post of my ‘A chessboard in MySQL’ where we create and populate a chessboard. But pieces need to move, and a few wondered how. Easy!

As an example, white openes with 1.e4:

BEGIN;
UPDATE chessboard SET e='♙' WHERE x = 4;
UPDATE chessboard SET e='' WHERE x = 2;
COMMIT;

Pretty obvious. Now lets put it in a stored procedure (source included in post) so the next move is easier on the fingers and more fun to play. Lets do a 1…e5:

CALL move_piece('e','7','e',5);

The result is the following:

mysql> SELECT * FROM chessboard;
+---+------+------+------+------+------+------+------+------+
| x | a    | b    | c    | d    | e    | f    | g    | h    |
+---+------+------+------+------+------+------+------+------+
| 8 | ♜    | ♞    | ♝    | ♛    | ♚    | ♝    | ♞    | ♜    |
| 7 | ♟    | ♟    | ♟    | ♟    |      | ♟    | ♟    | ♟    |
| 6 |      |      |      |      |      |      |      |      |
| 5 |      |      |      |      | ♟    |      |      |      |
| 4 |      |      |      |      | ♙    |      |      |      |
| 3 |      |      |      |      |      |      |      |      |
| 2 | ♙    | ♙    | ♙    | ♙    |      | ♙    | ♙    | ♙    |
| 1 | ♖    | ♘    | ♗    | ♕    | ♔    | ♗    | ♘    | ♖    |
+---+------+------+------+------+------+------+------+------+

Here is the stored procedure. It’s very, very basic, and of course, one can add much more!

DROP PROCEDURE IF EXISTS move_piece;
delimiter //
CREATE PROCEDURE move_piece(
    psrcCol CHAR(1),
    psrcRow TINYINT,
    pdstCol CHAR(1),
    pdstRow TINYINT)
BEGIN
    SET @srcCol = psrcCol;
    SET @srcRow = psrcRow;
    SET @dstCol = pdstCol;
    SET @dstRow = pdstRow;
    SET @piece = 0;
    SET @blank = '';
    
    -- Get the piece we are moving
    SET @stmt = CONCAT('SELECT ',@srcCol,
        '+0 INTO @piece FROM chessboard WHERE x = ?');
    PREPARE preStmt FROM @stmt;
    EXECUTE preStmt USING @srcRow;
    DEALLOCATE PREPARE preStmt;
    
    IF ((@piece > 1 AND @piece <= 14) AND @piece is not NULL)
    THEN
        -- Move the piece
        SET @stmt = CONCAT('UPDATE chessboard SET ',
            @dstCol,'=? WHERE x = ?');
        PREPARE preStmt FROM @stmt;
        EXECUTE preStmt USING @piece,@dstRow;
        DEALLOCATE PREPARE preStmt;
        SET @stmt = CONCAT('UPDATE chessboard SET ',
            @srcCol,'=? WHERE x = ?');
        PREPARE preStmt FROM @stmt;
        EXECUTE preStmt USING @blank,@srcRow;
        DEALLOCATE PREPARE preStmt;
    ELSE
        SELECT "No piece found at given position." AS Error;
    END IF;
END;
//

Some thoughts for future expansion:

• You could save the moves in a separate table to record time it took.
• Implement some other movement notation.
• Lock a player after a move.
• Build some other stored routines to populate and reset the chessboard.
• Have multiple chessboard tables.
• Event scheduler can be used to implement the non-human player!

Anyway, this was all about fun and Unicode testing. There will be probably no follow-up on this post. If somebody is crazy enough to actually implement a chess game in MySQL: awesome!

(Disclaimer: I am not a chess player.)

UPDATE 2009-12-31: Here is the insert statement for populating the chessboard:

INSERT INTO `chessboard` VALUES
  (8,'♜','♞','♝','♛','♚','♝','♞','♜'),
  (7,'♟','♟','♟','♟','♟','♟','♟','♟'),
  (6,'','','','','','','',''),(5,'','','','','','','',''),
  (4,'','','','','','','',''),<br />  (3,'','','','','','','',''),
  (2,'♙','♙','♙','♙','♙','♙','♙','♙'),
  (1,'♖','♘','♗','♕','♔','♗','♘','♖');

Something to keep you warm during cold winter nights, or cool during hot summer days: a chessboard in MySQL!

Note: You should see chess pieces here below. If not, you’re not watching it using UTF-8, or get yourself a good browser!

CREATE TABLE `chessboard` (
  `x` tinyint unsigned NOT NULL,
  `a` enum('','♔','♕','♖','♗','♘','♙','♚','♛','♜','♝','♞','♟'),
  `b` enum('','♔','♕','♖','♗','♘','♙','♚','♛','♜','♝','♞','♟'),
  `c` enum('','♔','♕','♖','♗','♘','♙','♚','♛','♜','♝','♞','♟'),
  `d` enum('','♔','♕','♖','♗','♘','♙','♚','♛','♜','♝','♞','♟'),
  `e` enum('','♔','♕','♖','♗','♘','♙','♚','♛','♜','♝','♞','♟'),
  `f` enum('','♔','♕','♖','♗','♘','♙','♚','♛','♜','♝','♞','♟'),
  `g` enum('','♔','♕','♖','♗','♘','♙','♚','♛','♜','♝','♞','♟'),
  `h` enum('','♔','♕','♖','♗','♘','♙','♚','♛','♜','♝','♞','♟')
) DEFAULT CHARSET=utf8;

Populating it with Python using MySQL Connector/Python (only piece of script shown):

def create_board(db):
    c = db.cursor()
    table = """CREATE TABLE chessboard (
        x tinyint unsigned not null,
        a ENUM('','\u2654','\u2655','\u2656','\u2657','\u2658','\u2659',            
            '\u265A','\u265B','\u265C','\u265D','\u265E','\u265F'),
        b ENUM('','\u2654','\u2655','\u2656','\u2657','\u2658','\u2659',
            '\u265A','\u265B','\u265C','\u265D','\u265E','\u265F'),
        c ENUM('','\u2654','\u2655','\u2656','\u2657','\u2658','\u2659',
            '\u265A','\u265B','\u265C','\u265D','\u265E','\u265F'),
        d ENUM('','\u2654','\u2655','\u2656','\u2657','\u2658','\u2659',
            '\u265A','\u265B','\u265C','\u265D','\u265E','\u265F'),
        e ENUM('','\u2654','\u2655','\u2656','\u2657','\u2658','\u2659',
            '\u265A','\u265B','\u265C','\u265D','\u265E','\u265F'),
        f ENUM('','\u2654','\u2655','\u2656','\u2657','\u2658','\u2659',
            '\u265A','\u265B','\u265C','\u265D','\u265E','\u265F'),
        g ENUM('','\u2654','\u2655','\u2656','\u2657','\u2658','\u2659',
            '\u265A','\u265B','\u265C','\u265D','\u265E','\u265F'),
        h ENUM('','\u2654','\u2655','\u2656','\u2657','\u2658','\u2659',
            '\u265A','\u265B','\u265C','\u265D','\u265E','\u265F')
        ) default charset='utf8'"""
    c.execute("DROP TABLE IF EXISTS chessboard")
    c.execute(table)

def set_start_position(db):
    c = db.cursor()
    # Numbers correspondent to the ENUM fields
    wdata = { 'x' : 1,
        'a': 4, 'b': 6, 'c': 5,
        'd': 3, 'e': 2,
        'f': 5, 'g': 6, 'h': 4}
    bdata = { 'x' : 8,
        'a': 10, 'b': 12, 'c': 11,
        'd': 9, 'e': 8,
        'f': 11, 'g': 12, 'h': 10}
    
    stmt = """UPDATE chessboard SET a=%(a)s,b=%(b)s,c=%(c)s,
        d=%(d)s,e=%(e)s,f=%(f)s,g=%(g)s,h=%(h)s WHERE x = %(x)s"""
    c.executemany(stmt, [wdata,bdata])
    
    stmt = """UPDATE chessboard SET a=7,b=7,c=7,d=7,e=7,f=7,g=7,h=7
        WHERE x = 2"""
    c.execute(stmt)
    stmt = """UPDATE chessboard SET a=13,b=13,c=13,d=13,e=13,f=13,g=13,h=13
        WHERE x = 7"""
    c.execute(stmt)

Now you can select the chessboard:

mysql> select * from chessboard;
+---+------+------+------+------+------+------+------+------+
| x | a    | b    | c    | d    | e    | f    | g    | h    |
+---+------+------+------+------+------+------+------+------+
| 8 | ♜    | ♞    | ♝    | ♛    | ♚    | ♝    | ♞    | ♜    |
| 7 | ♟    | ♟    | ♟    | ♟    | ♟    | ♟    | ♟    | ♟    |
| 6 |      |      |      |      |      |      |      |      |
| 5 |      |      |      |      |      |      |      |      |
| 4 |      |      |      |      |      |      |      |      |
| 3 |      |      |      |      |      |      |      |      |
| 2 | ♙    | ♙    | ♙    | ♙    | ♙    | ♙    | ♙    | ♙    |
| 1 | ♖    | ♘    | ♗    | ♕    | ♔    | ♗    | ♘    | ♖    |
+---+------+------+------+------+------+------+------+------+

The possibilities.. oh yeah!

clus·te·ri·ous |ˈkləstərēəs;|
adjective
highly pleasant to MySQL Support Engineers: A clusterious issue a day, keeps the spouse away.
· clusterful : a hard day.

DERIVATIVES
clusteriously adverb
clusteriousness noun

ORIGIN MySQL Support Team: via Sun Microsystems.

Clusterious
noun
a rare variety of MySQL Support Engineers originally cultivated in Sweden.

This bugged me for a long time, and just today I googled for a solution. And it’s darn simple! To set a new default column size, size them while holding the Option (Alt) key. Open a new Finder window, et voila: default size changed!

There are lots of these little tricks in Mac OS (and I’m sure in other desktop GUIs). Fun to find one each day!

Got to love unicode! Importing Ken Ishii‘s Jelly Tones album (btw, I won it at Studio Brussel in Belgium sending an email through BBS, somewhere in 1995!) I saw following in iTunes:

Found it pretty cool that ケン・イシイ shows up! I’m leaving as is. The Composer field is filled with ‘Ken Ishii’, so looking it up still works.

Today I got fed up with the Google Mail Notifier for Mac. Google is distributing a DMG package with only an install.sh script which opens again the website were you can download.. that same package!

I’m planning to drive the Main Square which is when you look from the sky to the the river Main, you can form a square. It will probably take me 2 or 3 days in total.

Yesterday I took on the first leg, which is probably the hardest one. It goes from Aschaffenburg over Laufach, Neuhütten, Rechtenbach and ending in Lohr am Main.

It was quite a tough ride through Spessart. In fact, I had to twice get off my bicycle, rest and continue the climb by foot. In total it was about 40km and took me 3 and a half hours. Bad luck my GPS ran out of battery to continue the tracking.

In Lohr am Main I took the train back to Aschaffenburg.

You might ask yourself why I’m running around with a beard in Summer, in Madrid? No, well, telling you anyway! I charged my beard trimmer leaving for Spain so it can last easily for a week, I rarely use it anyway. The problem? Apparently, while in my bag, it got turned on and happily got empty somewhere above France maybe.

Aah.. Vacation.. The time of the year you not only think about eating a burger and chocolate cake mixed with a Mexican beer, you actually do it.