sql query not working

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Maruthi Maruthi
Maruthi Maruthi 2017-3-28
评论： Guillaume 2017-3-28
In my code, there is a comparison of database record value stored in a variable and to fetch the corresponding record in the database using matlab. Please help me and the code is given below. here showing curs.Data is 0.
function ImagesExample(uname1)
%# read images in a cell array
disp(uname1);
imgs = cell(6,1);
for i=1:6
imgs{i} = imread( sprintf('C:/Users/maruthi1/Documents/MATLAB/images3/ma3%1d.jpg',i) );
end
%# show them in subplots
figure('Name','Image_mag','Numbertitle','off');
title('Image_mag');
for i=1:6
subplot(2,3,i);
h = imshow(imgs{i}, 'InitialMag',200, 'Border','tight');
title(num2str(i))
set(h, 'ButtonDownFcn',{@callback,i})
end
function callback(o,e,idx)
%# show selected image in a new figure
figure(2), imshow(imgs{idx})
title(num2str(idx))
promptMessage = sprintf('Drag out a box that you want to copy,\nor Cancel to abort processing?');
titleBarCaption = 'Continue?';
button = questdlg(promptMessage, titleBarCaption, 'Continue', 'Cancel', 'Continue');
if strcmpi(button, 'Cancel')
return;
end
A=imgs{idx};
n = input('Please enter the number of scenes you wish to crop: ')
ii=1;
%load user.mat
conn = database('mani','root','MARUTHI');
%setdbprefs('DataReturnFormat','cellarray');
curs=exec(conn,'select mobile_num from user2 where uname IN(uname1)');
%im_cropped = imcrop(A);
%B=imgs{idx};
%im_cropped = imcrop(B);
curs = fetch(curs);
curs.Data
m=curs.Data;
%C=imgs{idx};
while (ii<=n)
%[im_cropped rect] = imcrop(A);
im_cropped{ii} = imcrop(imgs{idx});
filename = ['images3\images_cropped' num2str(ii) '.jpg'];
imwrite(im_cropped{ii},filename);
ii=ii+1;
end
close(curs);
close(conn);
promptMessage = sprintf('Your cropped images saved successfully');
titleBarCaption = 'Continue?';
button = questdlg(promptMessage, titleBarCaption, 'Continue', 'Cancel', 'Continue');
if strcmpi(button, 'Cancel')
return;
end
end
%croping(A);
end

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回答（1 个）

Guillaume
Guillaume 2017-3-28
You've given us a lot of irrelevant code. Your SQL query is:
curs=exec(conn,'select mobile_num from user2 where uname IN(uname1)');
So it's searching for the literal string 'uname1' in the uname column of your user2 table. Is there such a string in that column?
Perhaps, uname1 is supposed to be replaced by the content of the uname1 variable. But matlab cannot guess that a particular arbitrary portion of a string has to be replaced with the content of a variable of the same name. You have to tell it to do so with sprintf or the newer compose:
curs = exec(conn, sprintf('select mobile_num from user2 where uname IN(%s)', uname1));
  2 个评论
Maruthi Maruthi
Maruthi Maruthi 2017-3-28
here uname1 is the username that was given in the field edit text and it is compare with user2 table. After modifying the code, it is displaying as zero. Please help me..
Guillaume
Guillaume 2017-3-28
What is displaying as zero?
Is the username found in the uname column of the user2 table. If not, then there's nothing to return.
If the type of the uname column is string. Then the search value need to be enclosed in quotes:
curs = exec(conn, sprintf('select mobile_num from user2 where uname IN (''%s'')', uname1));
Note that I've not changed your SQL. However, the IN clause usually specifies several values to look up, whereas you only have one (I assume), so:
curs = exec(conn, sprintf('select mobile_num from user2 where uname = ''%s''', uname1));
is probably better.

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