SQL - 来自2个表的条件的行和

Question

我有2个表，希望从条件中得到2个表的行和。 这是我的表格：

tabale1， tabale2

我想要来自2个表的行总和，例如：

if sk not null sum sk but if it is null sk = ss 

例如，sh2的总和为：19 + 5 + 11 + 5 = 40

我真的需要那个，请帮忙！

表1：

表2：

Answer 1

下一个sql将返回表中的总和，按名称分组：

select name, sum(total) total from 
(select name, sum(coalesce(sk,ss)) total
 from table1
 group by name
 union all
 select name, sum(coalesce(sk,ss)) total
 from table2
 group by name
) t
group by name

子查询中的“group by”子句非常重要，因为表是否返回了很多行，它们将减少查询中“group by”的行数，从而优化时间并减少使用内存。

Answer 2

如果sk不为空，请使用% --- Executes on button press in load. function load_Callback(hObject, eventdata, handles) % hObject handle to load (see GCBO) % eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA) % [flnm, flpth,cCheck]=uigetfile({'*.txt'},... % 'File Select',... % 'Multiset', 'on'); [flnm, flpth,cCheck]=uigetfile({'*.txt'},... 'File Select',... 'Multiselect', 'on'); %fullpathname=strcat(pathname, filename); %text=audioread(fullpathname); %set(handles.path_song, 'String',fullpathname);%show full path name in the listbox assignin('base','flnm',flnm); assignin('base','flpth',flpth); assignin('base','cCheck',cCheck); %If the user did not press the cancell button %If the user did not press the cancell button % if(cCheck==0) if(cCheck) %Reset selection to first entry set(handles.playlist,'Value',1); %Show selected filenames set(handles.playlist,'String',flnm); end %LIST------------------------Display Files--------------------------------- function playlist_Callback(hObject, eventdata, handles) % hObject handle to playlist (see GCBO) % eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA) % Hints: contents = cellstr(get(hObject,'String')) returns playlist contents as cell array % contents{get(hObject,'Value')} returns selected item from playlist listStr=get(hObject,'String'); listVal=get(hObject,'Value'); %Display Selected files if(iscell(listStr)) % % % fileName=playlistStr(listVal); fileName=char(listStr(listVal)); fprintf('Selected file:%s\n',fileName); else fileName=listStr; fprintf('Selected file:%s\n',fileName); end 选择sk。否则（如果sk为null），将使用ss。

coalesce两个表格，UNION ALL结果：

GROUP BY