Dbnameuser-whereuid$retuid-findweixin;

This code is incorrect as it is missing the "->field()" method to specify the field(s) to retrieve. The correct code would be:

Db::name('user')->where('uid', $ret['uid'])->field('weixin')->find();

This code selects the "weixin" field from the "user" table where the "uid" column matches the value in the $ret['uid'] variable and returns the first matching record.