Mysql实际使用过程中用到的执行语句记录SELECT 语句//将whs_material表中符合条件M_TYPE3和M_STATUS0的所有M_ID列出来SELECTM_IDFROMwhs_materialWHEREM_TYPE3ANDM_STATUS0//按日期的降序排列并且只显示前面10条SELECT*FROMivm_changerecordWHERES_CODE600009ORDERBYT_DATETIMEDESCLIMIT10//多字段排序示例SELECT*FROMstudents stORDERBYst.sAgeASC,st.sGradeDESC,st.sStuIdDESC;//查询数据表中某字段包含某内容SELECT*FROMbsc_userWHEREl_nameLIKE%hao%;多表查询SELECT#交叉连接(CROSS JOIN笛卡尔积)SELECT energy_meter_record.device_id,device_info.device_name FROM energy_meter_record,device_info;等效于 SELECT energy_meter_record.device_id,device_info.device_name FROM energy_meter_record crossjoindevice_info;#给交叉连接加上条件SELECT energy_meter_record.device_id,energy_meter_record.power,device_info.device_name FROM energy_meter_record CROSS JOIN device_info WHERE energy_meter_record.device_iddevice_info.device_id;#LEFT JOIN# 查询备忘录表中的分类ID为2的备忘录同时将分类ID的名称显示出来SELECT n.id AS note_id, n.content, n.create_time, c.id AS category_id, c.name AS category_name FROM note n LEFT JOIN category c ON n.category_idc.id WHEREn.category_id2语法 SELECT 列名 FROM 左表 LEFT JOIN 右表 ON 连接条件;**LEFT JOIN 的核心价值**以左表note)为主右表category匹配不到时补 NULL。ALTER语句#修改字段属性ALTERTABLEgroup_capacityINTNULL0COMMENT群组配额,#在表中添加一个字段ALTERTABLEtaskADDCOLUMNupdate_timeTIMESTAMPNOTNULLDEFAULTCURRENT_TIMESTAMPCOMMENT更新时间;insert into语句向表里插入数值insertintowhs_inventory_info(M_ID,ST_ID,LC_ID,I_GOOD_QTY,I_BAD_QTY,I_UPDATE_PERSON,I_UPDATE_TIME)values(M2109116,ST2111003,LC2112025,2,0,U2002001,2023-05-25 11:19:49);delete语句//删除whs_inventory_info里的所有数值但不影响表结构DELETEFROMwhs_inventory_infoUpdate语句//将通过语句SELECT * FROM meter_record WHERE periods2025-03查出来的所有行其中ifpayed字段部分全部修改为1UPDATEmeter_recordSETifpayed1WHEREperiods2025-03ANDifpayed!1;