报错：1054:Unknown column 'city' in 'where clause' [ SQL语句 ] : SELECT * FROM `iot_paths'WHERE....

错误提示：

1054:Unknown column 'xxx' in 'where clause' [ SQL语句 ] : SELECT * FROM `iot_paths` WHERE ( city= xx )

thinkPHP3.2   报错1054，百度搜索了下，发现是变量的数据类型错误导致的该问题，代码如下：

$cityInfos = $_SESSION['path'];
$pathinfo=$pathCity->where("city= {$cityInfos} ")->field('citys,appkeys,secrets,group')->find();

$pathinfo是字符串类型，需要在变量添加单引号，解决如下：

$cityInfos = $_SESSION['path'];
$pathinfo=$pathCity->where("city= '{$cityInfos}' ")->field('citys,appkeys,secrets,group')->find();