Prefixing multiple values within QGIS using the Field Calculator?

Question

I have a column in my my attribute table that contains a series of individually numbered locations. I wish to prefix all of these numbers with a letter, this letter will be the same for each of the values. E.g. 100, 200 and 300 would become A100, A200 and A300. I have a lot of data so simply going through and renaming would take a lot of time.

I have a feeling this would be achieved through the Field Calculator but unsure of which expression would be best for this?

Answer 1

Simple solution:

'A' ||  "column name" 

in a new field of type String.

Answer 2

You can use:

concat('A', "your_column" )

Note: Your column must accept Strings so if your current column type is set to integer, you will have to create a new field in the Field Calculator and set it to String.

Answer 3

The expression would be, for example:

'A'  ||  "someField" 

someField would be your field that you want to use when updating and || is used to concatenate strings in QGIS.

EDIT:
Make sure the values are put in between single quotes and the field names are put in between double quotes!