Extracting first digit of int in QGIS

Question

I have a field with number values (111,112,113,211,212,....) and want to extract only the first digit (111 -> 1, 259 -> 2 etc.).

I remember that there was some easy way to do that in field calculator, but not which it was.

Can anyone help?

I don't want to use CASE WHEN, since I have roughly 100 various numbers.

Answer 1

left("your field name here",1) will do the trick.

left() returns a string of a provided length from a field, counted from the left/beginning of the field.

Answer 2

Mathematically will be: "Field" // 10 ^ floor(log10("Field")) replace Field with the name of your field.

Answer 3

You can also use function regexp_substr:

Returns the portion of a string which matches a supplied regular expression.

 regexp_substr( "area", '(\\d{1})')

Which means, extract the first single digit