Question

I’ve a tableA with 2 columns (value1, value2) with a CSV formatted value. I want to create a tableB with the same fields as tableA but, in those 2 columns, with just a limit number of values (note that I don’t know how many characters exists between commas). This “limit” is the first n elements of the CSV.

Table A

+----+----------+----------------------+----------------------+
| id |   other  |        value1        |        value2        |
+----+----------+----------------------+----------------------+
| 1  |  other1  | 111,222,333,444      | 1616,17,1,8,19,2020  |
| 2  |  other2  | 55,6,7777,8,9        | 21,22,23             |
| 3  |  other3  | 10101,11.11,13,14,15 | 242424,2525,26,27    |
+----+----------+----------------------+----------------------+

Table B (limit to 3 elements)

+----+----------+----------------------+----------------------+
| id |   other  |        value1        |        value2        |
+----+----------+----------------------+----------------------+
| 1  |  other1  | 111,222,333          | 1616,17,1            |
| 2  |  other2  | 55,6,7777            | 21,22,23             |
| 3  |  other3  | 10101,11.11,13       | 242424,2525,26       |
+----+----------+----------------------+----------------------+

EDITED:

I didn’t mention that those tables have a huge number of elements (and many other columns like “other”). Therefore I prefer to use:

create table tableB LIKE tableA; 
INSERT tableB SELECT * FROM tableA; 

and then update the value1 and value2 (in 2 distinct transactions – in fact I’ve 91 columns like that). This probably is more efficient then a “create table” with all the values inside in a single query…

---

EDITED2 (solution):

SQLFiddle:

http://sqlfiddle.com/#!2/2e73a/1

Answer 1

You cam use MySQL’s SUBSTRING_INDEX() function, together with CREATE TABLE ... SELECT:

CREATE TABLE TableB
  SELECT id,
         other,
         SUBSTRING_INDEX(value1, ',', 3) AS value1,
         SUBSTRING_INDEX(value2, ',', 3) AS value2
  FROM   TableA

See it on sqlfiddle.