Select、LeftJoin用法、模糊查询的实现：LEFTJOIN关键字会返回左表（table_name1）的所有行，即使右表（table_name2）没有匹配的行。(业务需求：从一张表中查询到的数据要与另一张表相关联，实现模糊查询)constsql=`selectcei.intentionID,cei.engineerName,cei.nickname,cei.headImgUrl,ifnull(cmw.headImgUrl,'')inviteImgUrl,ifnull(cmw.nickname,'')inviteNickNamefromcm_engineer_intentionsceileftjoincm_member_wechatscmwoncmw.referralCode=cei.inviteCodewhere(:isGrant=-1orisGrant=:isGrant)and(:intentionStatus=-1orintentionStatus=:intentionStatus)and(:searchKey=''orconcat(engineerMobile,engineerName)likeconcat('%',:searchKey,'%'))orderbyintentionStatusasc,createTimedesc`;UpdateSet的用法（业务需求：传入一个字段时更新，不传入则忽略，方便根据需要选择是否插入字段）constcontactRemarkSql=是更新备注？',contactRemark=:contactRemark':'';constsql=`updatecm_engineer_intentionssetintentionStatus=:intentionStatus${contactRemarkSql}whereintentionID=:intentionID`;Delete、In的用法：（IN运算符允许我们在WHERE子句中指定多个值）下面的SQL语句可以删除满足条件的多条数据（业务需要请求：执行删除操作时，如果创建数据的人是操作数据的人，则删除，否则更新状态)constdeleteSql=deletefromcm_fast_order_goodswhereorderGoodsIDin(${deleteData.deleteIDs})andcreateUser=:userName;constupdateSql=updatecm_fast_order_goodssetstatus=0whereorderGoodsIDin(${deleteData.deleteIDs})andcreateUser!=:userName;Insert的用法（业务需求：新增一条数据）constsqlOrderEngineer=`insertintocm_order_engineers(orderEngineerID,orderGoodsID,orderID,engineerID,engineerName,createUser,createTime)values(:orderEngineerID,:orderGoodsID,:orderID,:engineerID,:engineerName,:createUser,:createTime)(业务需求：每新增一条数据，原数据中的一个字段+1)constsql=`insertintocm_engineers(engineerCode,loginName,password,engineerName,sex,birthDate,status,createUser,createTime)selectifnull(max(engineerCode),0)+1,:loginName,:password,:engineerName,:sex,:birthDate,:status,:createUser,now()fromcm_engineers`;（业务需求：将其他表的数据添加到当前表)insertintocm_fast_order_goods(orderGoodsID,orderID,goodsID,goods代码，goodsPicUrl，createUser，createTime）选择：orderGoodsID，：orderID，：goodsID，goodsCode，iconUrl，：createUser，现在（）来自cm_service_goodswheregoodsID=：goodsID和status=1
