Code for getting several characters from a field in SQ02

Hello Exports,

Please assist me with the next code.

I'm creating a query and need to get from MARA - MATNR field only 4 characters string.

For example the value in the field : 123456789 and I need the output to be 4567.

Please suggest the full code because I'm new to ABAP.

Thank you ,

TJ