Question

I’m trying to count how many essays have been graded so I know how many results to display on the page. But I can’t seem to get the code to work properly can someone help?

Thanks for the help in advance!

Here is what I got so far.

SELECT students.*, students_essays.*, COUNT(students_essays.id) 
FROM students  
INNER JOIN students_essays ON students.student_id = students_essays.student_id 
INNER JOIN essays_grades ON students_essays.id = essays_grades.students_essays_id

It should look something like the code below for my pagination.

 $q = "SELECT COUNT(id) FROM students_essays";
 $r = mysqli_query ($mysqli, $q) or trigger_error("Query: $q\n<br />MySQL Error: " . mysqli_error($mysqli));
 $row = mysqli_fetch_array ($r);
 $records = $row[0];

Just in case here is my MySQL tables.

CREATE TABLE students_essays (
id INT UNSIGNED NOT NULL AUTO_INCREMENT,
student_id INT UNSIGNED NOT NULL,
content TEXT NOT NULL,
PRIMARY KEY (id)
);


CREATE TABLE students (
student_id INT UNSIGNED NOT NULL AUTO_INCREMENT,
student_first_name VARCHAR(255) DEFAULT NULL,
student_last_name VARCHAR(255) DEFAULT NULL,
pass CHAR(40) NOT NULL,
PRIMARY KEY (student_id)
);


CREATE TABLE essays_grades (
id INT UNSIGNED NOT NULL AUTO_INCREMENT,
grade_id INT UNSIGNED NOT NULL,
students_essays_id INT UNSIGNED NOT NULL,
student_id INT UNSIGNED NOT NULL,
PRIMARY KEY (id)
);

CREATE TABLE grades (
id INT UNSIGNED NOT NULL AUTO_INCREMENT,
letter_grade VARCHAR(2) DEFAULT NULL,
grade_points FLOAT UNSIGNED NOT NULL DEFAULT 0,
PRIMARY KEY (id)
);

Here is the error message.

 Error: 1140 - Mixing of GROUP columns (MIN(),MAX(),COUNT(),...) with no GROUP columns is illegal if there is no GROUP BY clause in 

Answer 1

Well I am guessing here based on the information at hand…

$q = "SELECT COUNT(id) FROM students_essays se INNER JOIN essays_grades eg ON se.id = eg.students_essays_id"; 

That would return all essays with a matching grade record.