al隋茚粟胫tertabletabelnameaddnew_field_idint(5)unsigneddefault0not荏鱿胫协nullauto_increment,addprimarykey(new_field_id);//增加一个新列altertablet2adddtimestamp;altertableinfosaddextinyintnotnulldefault'0';//删除列altertablet2dropcolumnc;//重命名列altertablet1changeabinteger;//改变列的类型altertablet1changebbbigintnotnull;altertableinfoschangelistlisttinyintnotnulldefault'0';//重命名表altertablet1renamet2;//加索引mysql>altertabletablenamechangedepnodepnoint(5)notnull;mysql>altertabletablenameaddindex索引名(字段名1[，字段名2…]);mysql>altertabletablenameaddindexemp_name(name);//加主关键字的索引mysql>altertabletablenameaddprimarykey(id);//加唯一限制条件的索引mysql>altertabletablenameadduniqueemp_name2(cardnumber);//删除某个索引mysql>altertabletablenamedropindexemp_name;