Transforming a table

[Breka]

Hello All,

 

I have a problem that I can solve mathematically but is rather difficult in MySQL world.  Here is the issue: I have a table that looks like the following:

 

| label_a | label_b | label_c | label_d |

|    a    |  NULL  |  NULL  |  NULL  |

|  NULL  |    b      |  NULL  |  NULL  |

|  NULL  |  NULL  |    c      |  NULL  |

|  NULL  |  NULL  |  NULL  |    d    |

 

and I want it to look like the following:

 

| label_a | label_b | label_c | label_d |

|    a      |    b    |    c      |    d    |

 

Any thoughts?  I really want to stay away from subqueries as the tables are relatively massive.  Thank you!

[fenway]

What do those rows represent?

[Breka]

The rows are the result of an executed query.  I was hoping that there was some manner of transformation on the result set that didn't involve manipulation of the original query whatsoever.  For example, mathematically, I'd look at multiplying the matrix on the left by a n x 1 row vector of 1's to produce a n x 1 vector of values. 

[fenway]

Hmm... COALESCE() will return the first non-null value it finds, but that would mean you'd need to get the rows "joined" together first.