Question

any idea how to make this happen in MySQL:

Have Data:

Item, class, x, y, z, A, B, C
1,     new,  1, 0, 0, 1, 1, 0
2,     red,  1, 1, 0, 0, 1, 1
3,     new,  0, 0, 1, 1, 0, 1

(Data is also be in form 1, new, X, AB or 2, red, XY, BC if that is an easier point of departure…)

Need:

1, new, X, A
1, new, X, B
2, red, X, B
2, red, X, C
2, red, Y, B
2, red, Y, C
3, new, Z, A
3, new, Z, C

Any help would be awesomely appreciated. Thanks.

Answer 1

For few “xyzABC…” columns you can use this:

SELECT item,class,'x','A' FROM `test_pivot` WHERE x=1 AND a=1 UNION
SELECT item,class,'x','B' FROM `test_pivot` WHERE x=1 AND b=1 UNION
SELECT item,class,'x','C' FROM `test_pivot` WHERE x=1 AND c=1 UNION
SELECT item,class,'y','A' FROM `test_pivot` WHERE y=1 AND a=1 UNION
SELECT item,class,'y','B' FROM `test_pivot` WHERE y=1 AND b=1 UNION
SELECT item,class,'y','C' FROM `test_pivot` WHERE y=1 AND c=1 UNION
SELECT item,class,'z','A' FROM `test_pivot` WHERE z=1 AND a=1 UNION
SELECT item,class,'z','B' FROM `test_pivot` WHERE z=1 AND b=1 UNION
SELECT item,class,'z','C' FROM `test_pivot` WHERE z=1 AND c=1