用同一行中另一列的值替换一列中的子字符串

Question

I have a MySQL database with two columns, id and file :

id    file
1     /img/333.PNG
2     /img/452645.jpg
3     /img/1.gif

The file s are all the same path ( /img/ ), a number, and a graphics file extension, some in lower ( .png ), some in upper case ( .JPEG ).

How can I replace the path and numeric part of file with the id (from the same row)?

The result for the above sample should look like:

id    file
1     1.PNG
2     2.jpg
3     3.gif

Notes:

• I don't want to rename the actual files, just the database entries.
• I want to rename file in all rows using only one query.

Answer 1

This should work

UPDATE table SET file = CONCAT(id, '.', RIGHT(file, 3));

To accommodate JPEG extension locate position of dot.

UPDATE table SET file = CONCAT(id, SUBSTRING(file, POSITION('.' IN file)));