I stored the symbols in a table in a database, e.g.
country | currency_code | currency_symbol | currency_rate
UK GBP £ 1.0000
EU EUR € 1.XXXX
USA USD $ 1.XXXX
Canada CAD $ 1.XXXX
The problem is that the currency symbols are not valid in html so they show up as � instead.
Do I need to add another column to my table for HTML codes e.g. £ € $ or is there a simple function in PHP that I can use to wrap around the character to convert it to HTML?
Currency symbols are perfectly "HTML safe". What you have is an encoding problem. You are outputting these characters encoded in one encoding (likely Latin-1), but your browser is interpreting them in some other encoding (likely UTF-8). The actual encoding and the declared encoding need to match. Follow this answer or Handling Unicode Front To Back In A Web App to see where your problem is.