As I am new to MySQL, this question may be silly. How can I find the difference between successive rows?  

Example:  

A table (tableName='Abc') contains a single row as follows,

```
|DATA|
|10  |
|20  |
|30  |
|40  |
|50  |

```

Here I want get the output as,

```
|Dif|
|10 |
|10 |
|10 |
|10 |

```

How to find the difference like this without any index (primary or Auto\_increment)?