Question

All data in column foo are suffixed by a _. I want to delete this _. Can I do it using SQL rather than writing a script?

Answer 1

A few ways to do it:

• TRIM the trailing ‘_’:

  UPDATE mytable
  SET foo = TRIM(TRAILING '_' FROM foo)
  

• Grab the substring consisting of characters 1 to n-1, n being the length of the string in foo, using SUBSTRING and CHAR_LENGTH:

  UPDATE mytable
  SET foo = SUBSTRING(foo,1,CHAR_LENGTH(foo)-1)
  

I’d recommend the first method as, if you have, say, one row in foo that doesn’t end in ‘_’, the first method will leave it as is, whereas the second will take of its last character even though that isn’t an underscore.