Question: ```
#!/usr/bin/env python
# coding=utf8
  value=input("please enter value:")
  result=hex(value)
  r=hex(0xffff-result)
  print r
  print result

TypeError: unsupported operand type(s) for -: 'int' and 'str'

```

I study python for a few days,I try this python job,I can't understand what's the shape of '0xffff',it is str or int?and it's right for 'result' be str?

Answer: 
Since you are not getting a syntax error and you have only a small number of rows, the most likely reason is that there is another process that's holding a lock on this table. Please connect any other clients that you have open. This could be other instances of mysql work bench, a long running script, the django console and so many things.

Then try the query again. If that still doesn't work, try `SHOW OPEN TABLES`

<https://dev.mysql.com/doc/refman/5.7/en/show-open-tables.html>
Try this.

`ALTER TABLE test MODIFY COLUMN title VARCHAR(500);`

I think you are missing the *keyword* `COLUMN`