wpdb::determine_charset() WordPress Method

The wpdb::determine_charset() method is used to set the character set for the WordPress database. By default, this is set to latin1.

wpdb::determine_charset( string $charset, string $collate ) #

Determines the best charset and collation to use given a charset and collation.

Description
Parameters
Return
Source
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Description

For example, when able, utf8mb4 should be used instead of utf8.

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Parameters

$charset: (string)(Required)The character set to check.
$collate: (string)(Required)The collation to check.

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Return

(array) The most appropriate character set and collation to use.

'charset'
(string) Character set.
'collate'
(string) Collation.

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Source

File: wp-includes/wp-db.php

public function determine_charset( $charset, $collate ) {
    if ( ( $this->use_mysqli && ! ( $this->dbh instanceof mysqli ) ) || empty( $this->dbh ) ) {
        return compact( 'charset', 'collate' );
    }
 
    if ( 'utf8' === $charset && $this->has_cap( 'utf8mb4' ) ) {
        $charset = 'utf8mb4';
    }
 
    if ( 'utf8mb4' === $charset && ! $this->has_cap( 'utf8mb4' ) ) {
        $charset = 'utf8';
        $collate = str_replace( 'utf8mb4_', 'utf8_', $collate );
    }
 
    if ( 'utf8mb4' === $charset ) {
        // _general_ is outdated, so we can upgrade it to _unicode_, instead.
        if ( ! $collate || 'utf8_general_ci' === $collate ) {
            $collate = 'utf8mb4_unicode_ci';
        } else {
            $collate = str_replace( 'utf8_', 'utf8mb4_', $collate );
        }
    }
 
    // _unicode_520_ is a better collation, we should use that when it's available.
    if ( $this->has_cap( 'utf8mb4_520' ) && 'utf8mb4_unicode_ci' === $collate ) {
        $collate = 'utf8mb4_unicode_520_ci';
    }
 
    return compact( 'charset', 'collate' );
}