关联视图 · v9.1核心开发版

* 关联视图案例（ LEFT JOIN ） ~~~ $field = []; $obj = []; $obj['id'] = 'id'; $obj['field1'] = 'field1'; $field['table1'] = [$obj,'id']; $obj = []; $obj['field2'] = 'field2'; $field['table2'] = [$obj,'id']; $back = $D_P->view("view_name",$field,2); $back = $D_P->view("view_name",$field,2,['echo'=>1]); ~~~ > 注：字段名称不能重复，可用每组1的值定义判断字段名