了解了如何查找PHP问题。我现在正在尝试解决它们，但我对此一无所知。我使用了mysql_error并发现:1054:Unknowncolumn'o.user_id'in'onclause'这有什么问题吗:$sql="SELECTo.*,u.user_name,u.email,od.artist_id,cm.nexchange_priceFROM".$tableprefix."orderso,".$tableprefix."currency_mastercmINNERJOIN".$tableprefix."usersuONo.user_id=u.user_idINNERJOIN".$ta

为我的Yii应用做一个小组件。代码$connection=Yii::app()->getComponent('db');$sql='SELECT*FROM{{settings}}';$command=$connection->createCommand($sql);引发错误SQLSTATE[42000]:Syntaxerrororaccessviolation:1064YouhaveanerrorinyourSQLsyntax;checkthemanualthatcorrespondstoyourMySQLserverversionfortherightsyntaxtousenear'