# MỞ RỘNG KÝ TỰ CHO CỘT MÃ

```
// Tăng ký 001 => 0001 do tràn ký tự
// sử dụng hàm STUFF(string gốc, vị trí chèn, số lượng ký tự xoá, ký tự mới cần chèn)
// số lượng ký tự xoá: nếu không xoá thì để =0
select ma,stuff(ma,7,0,'0'),vattu from vattu where ma like 'lodot.%'
update vattu set ma = stuff(ma,7,0,'0'),modidate=getdate() where ma like 'lodot.%'
```


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