Each collation must have a unique ID. To add a new collation, you must choose an ID value that is not currently used. The value must be in the range from 1 to 254. The collation ID that you choose will show up in these contexts:

To display a list of the currently used collation IDs, use this statement:

mysql> SHOW COLLATION;
+----------------------+----------+-----+---------+----------+---------+
| Collation            | Charset  | Id  | Default | Compiled | Sortlen |
+----------------------+----------+-----+---------+----------+---------+
| big5_chinese_ci      | big5     |   1 | Yes     | Yes      |       1 |
| big5_bin             | big5     |  84 |         | Yes      |       1 |
...
| latin1_german1_ci    | latin1   |   5 |         | Yes      |       1 |
| latin1_swedish_ci    | latin1   |   8 | Yes     | Yes      |       1 |
| latin1_danish_ci     | latin1   |  15 |         | Yes      |       1 |
| latin1_german2_ci    | latin1   |  31 |         | Yes      |       2 |
| latin1_bin           | latin1   |  47 |         | Yes      |       1 |
| latin1_general_ci    | latin1   |  48 |         | Yes      |       1 |
| latin1_general_cs    | latin1   |  49 |         | Yes      |       1 |
| latin1_spanish_ci    | latin1   |  94 |         | Yes      |       1 |
| latin2_czech_cs      | latin2   |   2 |         | Yes      |       4 |
| latin2_general_ci    | latin2   |   9 | Yes     | Yes      |       1 |
| latin2_hungarian_ci  | latin2   |  21 |         | Yes      |       1 |
| latin2_croatian_ci   | latin2   |  27 |         | Yes      |       1 |
| latin2_bin           | latin2   |  77 |         | Yes      |       1 |
...
+----------------------+----------+-----+---------+----------+---------+

Look through the values in the Id column and pick a value that is not used.