1.新建字段ALTERTABLE表名ADDCOLUMN新字段名 字段类型;altertabledatabase1.tablename1addcolumnnew_fieldvarchar(255)二、改变字段长度ALTERTABLEyour_tableALTERCOLUMNyour_columnTYPEVARCHAR(5000);三、删除表数据1全部删除TRUNCATETABLE表名;2按条件删除DELETEFROM表名WHERE过滤条件DELETEFROMproductsWHEREprice10;四、基于现有查询结果根据某个字段去重基于字段D去重WITHoriginalAS(SELECT*FROMyour_table)SELECT*FROM(SELECT*,ROW_NUMBER()OVER(PARTITIONBYDORDERBYid)ASrnFROMoriginal)tWHERErn1;五、重命名约束ALTERTABLE...RENAMECONSTRAINTALTERTABLEtable_bRENAMECONSTRAINTpk_table_aTOpk_table_b;