What is the command to replace value of all the field record in a table using phpmysql?

Example:
I have a table called country, and there is a filed country name. Currently I have about 50 records that have various countries, I need to replace all the records country = USA

Tks

Use the SQL option in PHPMyADMIN:

UPDATE tblcountries SET countryField = 'USA'

This will replace all values in your field, you can also add a where close if required