How to copy names from one table to another in a specific case?

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Hello everyone, I am building an attendant system, and I have two tables (students- attend)
So, all the students will be registered at the student table let’s say we only have five students as shown in the photo.
When the student signed in, he/she will be inserted to attend table as shown in the photo and the word present will be written under attend table head.
But I want when I click a button after the class finish to insert the rest of the student that didn’t sign in in this case (Sara and Zain) to attend table with the word absent. How I can do that.

Here is the photo
Thank you

What I have tried:

I succeed when inserting the present student. I tried to do a join between tables but can't do it correctly + I don't know if joining between tables is the perfect solution and if yes I don't know how to ably it correctly.

Posted 17-Jan-22 10:00am

proud_developer

Updated 17-Jan-22 10:28am

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M Imran Ansari · Answer 1 · 2022-01-17T10:12:00

Solution 1

Try the following query to insert absent students into attend table on a button click:
'Day_date: 2022-01-17 is the control date on which you are performing action. You can pass the parameter to run this query'

SQL Query:

INSERT INTO attend
SELECT Id, Number, fullName, 'absent', '2022-01-17'
FROM student 
WHERE Id NOT IN (SELECT Stu_id FROM attend WHERE Day_date = '2022-01-17')

MySQL Query:

INSERT INTO attend
SELECT Id, Number, fullName, 'absent', '2022-01-17'
FROM student 
WHERE Id NOT IN (SELECT Stu_id FROM attend WHERE Day_date = '2022-01-17')

Posted 17-Jan-22 10:12am

M Imran Ansari

Comments

Maciej Los 17-Jan-22 16:22pm

As far as i understand, you OP is able to insert data into another table...

M Imran Ansari 17-Jan-22 16:29pm

Yes. As per problem statement "insert the rest of the student that didn’t sign in into attend table"

proud_developer 17-Jan-22 17:32pm

yes I want the rest of the students that are not at attend table, I will try the query and see its result. Thank you.

proud_developer 17-Jan-22 17:53pm

I write this query and when I execute it, doesn't insert anything to the attend table:
$q = INSERT INTO attend SELECT id, fullName, number, 'absent', 'curdate()'
FROM student
WHERE id NOT IN (SELECT stu_id FROM attend WHERE day_date = 'curdate()')";

curdate = the current date because I inserted date with current date and system will take the attendant once every day.

M Imran Ansari 18-Jan-22 5:59am

What is value of curdate()? and check the format of date which already exists inthe attend table.

proud_developer 18-Jan-22 6:54am

It is the current date of the day.
I already use curdate() when I insert present and it work just fine

M Imran Ansari 18-Jan-22 6:55am

Have you checked the date format of inserted records of attend table?

proud_developer 18-Jan-22 6:57am

Yeah, it is a date format, I uploaded in my original question an image that contains the table structure that I took a screenshot of my tables in PHPMyAdmin designer.

M Imran Ansari 18-Jan-22 8:10am

In your attached image date format of Day_date = '2022-01/17' but when we call CURDATE() it returns '2022-01-17'. Please check the format of inserted data.

CHill60 18-Jan-22 8:10am

Is it a "Date" or a "Datetime" - if the latter then you can't use "equals"

proud_developer 18-Jan-22 8:19am

I use this query when the student signs in to attend and it works just fine using curdate in it.

INSERT INTO attend (std_id,number, stuName, attend, day_date) VALUES ('$stID','$stuID', '$fullname', 'present', curdate())

M Imran Ansari 18-Jan-22 8:29am

After this query Day_date should be like '2022-01-18' and see your attend table (as per attached image) date is saving like '2022-01/17'. Why so?

proud_developer 18-Jan-22 8:46am

It is a typo I wrote these two tables in MS Word for for the explaining purpose. But the two tables with green line I took screen shot from my database on phpmyadmin

Maciej Los · Answer 2 · 2022-01-17T10:28:00

If i understand you correctly... you want to display all 5 records from attend table and corresponding data from student table.

So, use LEFT JOIN:

SQL

SELECT A.*, B.*
FROM attend AS A
LEFT JOIN student AS B ON A.number = B.number

For further details, please see:
Visual Representation of SQL Joins[^]
SQL Joins[^]

Dave Kreskowiak · Answer 3 · 2022-01-17T10:28:00

Solution 3

You do NOT copy names from one table to another. That's duplicating data and it's wasteful.
If you need to change the state of a student in the "attend" table, you put the ID of the student in that table, not the student's name.

Posted 17-Jan-22 10:28am

Dave Kreskowiak

Comments

proud_developer 17-Jan-22 17:31pm

but I am using a PHP spreadsheet to print out the content of the attend table to xlxs file and I achieve that + I am not very good with MySQL and I am still trying to understand and ably the concept of joining tables together.