How to write new data to the existing excel file?

Respected All,

Hello everyone! I wanna add new data to the existing excel file from the last row of it. How can I do that please? I have tried and the error appeared "The number of table variables in an assignment must match.". And I opened that "Results.xlsx" file which is too small grid cells (attached photo).

Please someone suggest and help me. Thanks all.

Here example code:

Dtime = datetime('now','TimeZone','local','Format','d-MMM-y HH:mm:ss');
Name = {'Alex'};
DateAndTime = Dtime;
ConfidenceScore = 95;

if isfile('Results.xlsx')
    T1 = readtable('Results.xlsx');
    [rd, cd] = size(T1);
    T = table(Name, DateAndTime, ConfidenceScore);
    T1(rd+1, 1:cd-1) = T;
    writetable(T1,'Results.xlsx');
else
    T = table(Name, DateAndTime, ConfidenceScore);
    writetable(T,'Results.xlsx');
end

Answer 1

[Simon Chan]

You may replace the entire loop by using 'Append' as follows:

writetable(T,'Results.xlsx','UseExcel', true, 'WriteMode','Append') 

[Alex Zai]

Thanks for your answer. But didn't work :(.

Error "The number of table variables in an assignment must match."

[Simon Chan]

You may refer to the following code to modify yours, there is no need for the if-else loop unless I misunderstand your issue.

for k = 1:10
    Dtime = datetime('now','TimeZone','local','Format','dd-MMM-yyyy HH:mm:ss');        
    Name = {'Alex'};                                                                    % Name
    DateAndTime = Dtime;                                                                % Date and time                      
    ConfidenceScore = 95;                                                               % Confidence Score
    pause(1);                                               % Just add more time to show time difference
    T = table(Name, DateAndTime, ConfidenceScore);          % Create the table
    writetable(T,'Results.xlsx','UseExcel', true, 'WriteMode','Append')                 % Write to excel
end

Then, check the result using funtion readtable as follows:

readtable('Results.xlsx')

Resut like that:

ans =
  10×3 table
      Name          DateAndTime         ConfidenceScore
    ________    ____________________    _______________
    {'Alex'}    28-Aug-2021 20:59:29          95       
    {'Alex'}    28-Aug-2021 20:59:30          95       
    {'Alex'}    28-Aug-2021 20:59:32          95       
    {'Alex'}    28-Aug-2021 20:59:33          95       
    {'Alex'}    28-Aug-2021 20:59:34          95       
    {'Alex'}    28-Aug-2021 20:59:36          95       
    {'Alex'}    28-Aug-2021 20:59:38          95       
    {'Alex'}    28-Aug-2021 20:59:39          95       
    {'Alex'}    28-Aug-2021 20:59:40          95       
    {'Alex'}    28-Aug-2021 20:59:42          95            

[Alex Zai]

Thanks for your answer. I understood your answer. But I want to do that...

Name = {'Alex'}; %may be other name in every time. DateAndTime = Dtime; %may be another time. ConfidenceScore = 95; %also another score (different)

This 3 value are updating when i run code (means may be different).

So I want to add these updated (news) value into existing table after the last row. Here example code I was a little change. Hope you will understand and you can help me.

I already run this example code and appeared error -

An error occurred when concatenating the table variable 'DateAndTime' using VERTCAT.

Caused by:

Error using datetime/vertcat (line 1394)

Unable to concatenate a datetime array that has a time zone with one that does not have a time

zone.

Dtime = datetime('now','TimeZone','local','Format','d-MMM-y HH:mm:ss Z');
Name = {'Alex'};
DateAndTime = Dtime;
ConfidenceScore = 80;

if isfile('Results.xlsx')
    T1 = readtable('Results.xlsx');
    Tnew = table(Name, DateAndTime, ConfidenceScore);
    T = [T1; Tnew];
    writetable(T, 'Results.xlsx','WriteMode','Append');
else
    T = table(Name, DateAndTime, ConfidenceScore);
    writetable(T,'Results.xlsx', 'WriteMode','Append');
end                             

[Simon Chan]

If you still want to use the if-else-end, there is no need to use 'Append' for writetable.

The issue of having an error is simply due to the datetime format read back from the excel file which is not the same as the datetime format of the variable Dtime.

So you may try to convert the datetime format once again to make sure they are consistenct before writing to excel. (Added one line after readtable as shown below)

Dtime = datetime('now','TimeZone','local','Format','d-MMM-y HH:mm:ss Z');
Name = {'Alex'};
DateAndTime = Dtime;
ConfidenceScore = 80;
if isfile('Results.xlsx')
    T1 = readtable('Results.xlsx');
    T1.DateAndTime = datetime(T1.DateAndTime,'TimeZone','local','Format','d-MMM-y HH:mm:ss Z');
    Tnew = table(Name, DateAndTime, ConfidenceScore);
    T = [T1; Tnew];
    writetable(T, 'Results.xlsx');
else
    T = table(Name, DateAndTime, ConfidenceScore);
    writetable(T,'Results.xlsx');
end