/**
* 构造 FROM 子句
*
* @return string
*/
protected function _renderFrom()
{
$from = array();
foreach ($this->_parts[self::FROM] as $alias => $table) {
$tmp = '';
// $this->_parts[self::FROM][$alias] = array(
// 'join_type' => $join_type,
// 'table_name' => $table_name,
// 'schema' => $shema,
// 'join_cond' => $where_sql, // 字符串
// );
// 如果不是第一个 FROM，则添加 JOIN
if (!empty($from)) {
$tmp .= ' ' . strtoupper($table['join_type']) . ' ';
}
if ($alias == $table['table_name']) {
$tmp .= $this->_conn->qid("{$table['schema']}.{$table['table_name']}");
} else {
$tmp .= $this->_conn->qid("{$table['schema']}.{$table['table_name']}", $alias);
}
// 添加 JOIN 查询条件
if (!empty($from) && !empty($table['join_cond'])) {
$tmp .= "\n " . self::SQL_ON . ' ' . $table['join_cond'];
}
$from[] = $tmp;
}
if (!empty($from)) {
return "\n " . self::SQL_FROM . ' ' . implode("\n", $from);
} else {
return '';
}
}
