This question already has an answer here:
I recently upgraded my site to PHP 5.7 and a new install of the MySQL database. The previous data was imported.
Now I have a lot of the question marks in diamonds in outputted text. I have read up, and the problem seems to be that the collation of my database is set to latin1_swedish_ci and I need to be utf8 to correctly render special characters stored in the database.
If I change the collation will this potentially solve my problem, fixing the older postings?
Do I switch off the site before changing the collation, and does it require a reboot to take effect? I'm a little nervous about corrupting the data as my users would be extremely upset to lose their historical postings.
I am not setting up a new database, I've upgraded an existing database, and need to keep the historical data.
I followed one of the answers posted below and it worked for data that was inputted into the database before the upgrade, but now renders newer data with various “ in place of apostrophes, etc.
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You can use
$con = mysqli_connect("HOST","DB_USER","PASSWORD","DB_NAME");
$db->set_charset('utf8');
OR
mysql_query('SET NAMES utf8');