Possible to search/replace AND swap positions of values in MySQL? - php

Question

Is it possible to use a query to swap positions of characters within the SAME value/column?
Example, I have a large table with a column that lists sizes like so:
12x24 Bulletin
7x14 Bulletin
14x48 Bulletin, etc.
The problem is now my boss has decided that he wants it to read:
Bulletin 12x24
Bulletin 7x14
Bulletin 14x48
Is it possible to swap those positions with a query or a regular expression? Or do I have to go manually update each record (very time consuming as there aprrox. 500 records to be modified)? Thanks for your help!

Answer 1

Is it always a whitespace between this two values? If yes, you can select your records like this:
SELECT CONCAT(SUBSTRING_INDEX(details, ' ', -1),' ',SUBSTRING_INDEX(details, ' ', 1)) AS value FROM tableName
SQL Fiddle: http://sqlfiddle.com/#!2/a04d8d/6
Table schema for this query I used:
CREATE TABLE tableName (
id int auto_increment primary key,
details varchar(30));
INSERT INTO tableName (id, details)
VALUES (NULL,'12x24 Bulletin'), (NULL,'7x14 Bulletin');

Answer 2

Here's what seems natural to me, though not too flexible:
UPDATE SOMETABLE
SET SOMECOLUMN = CONCAT('Bulletin ', REPLACE(SOMECOLUMN, ' Bulletin', ''))
WHERE SOMECOLUMN LIKE '% Bulletin'
;

Answer 3

Yes. It is possible.
The "trick" is to write an expression that returns the new value to be assigned.
It looks like you could achieve what you want by finding occurrences of ' Bulletin' and replacing that with an empty string, and pre-pending the remaining value with 'Bulletin '.
Here's a demonstration...
-- test cases
CREATE TABLE foo (id INT UNSIGNED AUTO_INCREMENT PRIMARY KEY, mycol VARCHAR(255))
INSERT INTO foo (mycol) VALUES ('12x24 Bulletin'),('7x14 Bulletin'),('14x48 Bulletin')
-- test expression to return new value to be assigned
SELECT mycol AS oldval
, CONCAT('Bulletin ',REPLACE(mycol,' Bulletin','')) AS newval
FROM foo
WHERE mycol LIKE '% Bulletin%'
-- use that expression in an UPDATE statement to replace the value
UPDATE foo
SET mycol = CONCAT('Bulletin ',REPLACE(mycol,' Bulletin',''))
WHERE mycol LIKE '% Bulletin%'
There are some gotchas to be aware of in the UPDATE statement, such as referencing a column in an expression after it's assigned a value. (Not a problem in the example I gave above, but it can be in the more general case.
Note: The MySQL REGEXP operator returns a boolean, not a string function, so, no, you can't "use a regular expression" to return a replacement value. You could use REGEXP in place the LIKE operator in the examples above.
FOLLOWUP
The above assumes you want to update the values stored in a table. If you only want to do the modification at the time you pull the data, you could use an expression in the SELECT list, similar to the above.
INSERT INTO foo (mycol) VALUES ('Stapler 12')
SELECT IF(mycol LIKE '% Bulletin'
,CONCAT('Bulletin ',REPLACE(mycol,' Bulletin',''))
,mycol
) AS mycol
FROM foo

Answer 4

If those examples hold true, then you can do the swapping by doing:
update t
set col = ws_concat(' ', substring_index(col, ' ', -1), substring_index(col, ' ', 1)
where col like '% Bulletin';
Alternatively, you could just do this when you query on the column:
select ws_concat(' ', substring_index(col, ' ', -1), substring_index(col, ' ', 1) as size,
<other columns
from t;
However, the existence of the problem suggests that you are stuffing two types of information into a single column. You should consider having two columns -- in your case, one would contain 'Bulletin' (some sort of "sizetype" column) and another would have the dimensions. You might even want to split the dimensions into additional columns.
Actually, as I write this, I suspect that you are missing an entity in your database. This column should actually be a foreign key to a sizes table. That table would have one row per size thingee. You can then have various columns for representing the size to suite you, your boss, your boss's boss, or whoever.