Transfer data from certain postgresql table fields to single hstore field

fields_to_hstore.php

<?php

$fields = [
    'field_1',
    'field_2',
    'field_3',
    'date_field',
    'field_6',
    'field_7',
];
$glue = '~~~';
$selectPattern = "(CASE WHEN (%s IS NOT NULL%s) THEN ('%s' || '$glue' || %s || '$glue') ELSE '' END)";
$select = [];
foreach ($fields as $field) {
    $replacements = array_fill(0, 4, $field);
    if ('date_field' === $field) {
        $replacements[1] = '';
        $replacements[3] = "TO_CHAR(date_field, 'YYYY-MM-DD')";
    } else {
        $replacements[1] = " AND $field != ''";
    }
    $select[] = vsprintf($selectPattern, $replacements);
}
$select = implode(' || ', $select);

foreach (['table_1', 'table_2'] as $table) {
    executeSql("
        UPDATE {$table}
        SET attributes = hstore(string_to_array(rtrim(($select), '~'), '{$glue}'))
        WHERE some_field != 'someValue'
    ");
}