Question

I’ve a “TableOriginal” that I want to “split” into multiple tables, each one with the name of the different values than can be found on “split” column in “tableOriginal“. The name, therefore, must be dynamic (maybe formed by a variable that is the result of a previous query).

TableOriginal:

+----+-------+-------+
| id | split | value |
+----+-------+-------+
| 1  |   A   |  v1   |
| 2  |   A   |  v2   |
| 3  |   A   |  v3   |
| 4  |   B   |  v4   |
| 5  |   B   |  v5   |
| 6  |   B   |  v6   |
| 7  |   C   |  v7   |
| 8  |   C   |  v8   |
| 9  |   A   |  v9   |
| 10 |   B   |  v10  |
| 11 |   B   |  v11  |
| 12 |   C   |  v12  |
+----+-------+-------+

TableSplit_A

+----+-------------+-------+
| id | original_id | value |
+----+-------------+-------+
| 1  |      1      |  v1   |
| 2  |      2      |  v2   |
| 3  |      3      |  v3   |
| 4  |      9      |  v9   |
+----+-------------+-------+

TableSplit_B

+----+-------------+-------+
| id | original_id | value |
+----+-------------+-------+
| 1  |      4      |  v4   |
| 2  |      5      |  v5   |
| 3  |      6      |  v6   |
| 4  |      10     |  v10  |
| 5  |      11     |  v11  |
+----+-------------+-------+

TableSplit_C

+----+-------------+-------+
| id | original_id | value |
+----+-------------+-------+
| 1  |      7      |  v7   |
| 2  |      8      |  v8   |
| 3  |      12     |  v12  |
+----+-------------+-------+

SQLFiddle:

http://sqlfiddle.com/#!2/61266

Answer 1

You can probably use VIEW for this. For the dynamic approach see the TEMPTABLE argument to the VIEW.

In the VIEW’s Create query you then use alias for the column name.

In my opinion dynamics in relation should be handled in code and not in procedures on server. Anyways, here’s an example:

CREATE ALGORITHM=UNDEFINED 
DEFINER=`user`@`yourserver` 
SQL SECURITY DEFINER 
VIEW `tableA` AS select `tableoriginal`.`id` AS `id`,
     `tableoriginal`.`split` AS `tableoriginal_A`,
     `tableoriginal`.`value` AS `value` 
from 
     `tableoriginal` 
where
     (`tableoriginal`.`split` = 'A')

Now you can query TableA as any other table (I skipped the TEMPTABLE in this example).

Hope this was related to what you where looking for.

Added to fiddler:
http://sqlfiddle.com/#!2/c4304/1

UPDATE: (based on the comments below)

Personally I work by the STORE-NOP principle 😛 use a database only to STOre-REtrieve-NOt-for-Processing ™, so I would do it in two steps:

select distinct split from TableOriginal;

Then go through each result and inject the result in a pre-defined query (notice {0} in the string, these will be replaced later – and perhaps different in the language you’re using):

myView = "CREATE ALGORITHM=UNDEFINED 
SQL SECURITY DEFINER 
VIEW `table{0}` AS select `tableoriginal`.`id` AS `id`,
     `tableoriginal`.`split` AS `tableoriginal_{0}`,
     `tableoriginal`.`value` AS `value` 
from 
     `tableoriginal` 
where
     (`tableoriginal`.`split` = '{0}')
;"

Then run the query for each line in result (pseudo code in VB):

For Each line In DBQueryResult
  cmd.ExecuteWrite(String.Format(myView, line.field("split"))
Next

I cannot check right now if these are valid statement, but it’s meant as pseudo code so you can get the idea how you can do this in the language you are using.

You also might want to consider use a IF EXIST/DROP VIEW or a TEMPTABLE in the final query.