framework/db/Schema.php
public function getSchemaNames($refresh = false)
    {
        if ($this->_schemaNames === null || $refresh) {
            $this->_schemaNames = $this->findSchemaNames();
        }

        return $this->_schemaNames;
    }
public function getSchemaNames($refresh = false)
    {
        if ($this->_schemaNames === null || $refresh) {
            $this->_schemaNames = $this->findSchemaNames();
        }

        return $this->_schemaNames;
    }
Returns all schema names in the database, except system schemas.
@param bool $refresh whether to fetch the latest available schema names. If this is false,
schema names fetched previously (if available) will be returned.
@return string[] all schema names in the database, except system schemas.
@since 2.0.4