How To Count Total Present Attendance From Database - mysql

Question

I have a table where I need to count all present to show how many attendance student have
In my table have Following Column
school id
Student id
year
Month
Status
day_1
day_2
day_3
To
day_31
entry goes once in a month. Like
if new month new row create
else update in day_ 1 day_2 day_3 etc.

Answer 1

Here's a different trick. Although it's for MySql 8.0+
Concatinate the day_n fields into a string.
Then remove all the characters that aren't 'P' from that string.
Then the character length of the remaining string will be the total 'P'.
SELECT school_id, student_id, month, year,
CHAR_LENGTH(
REGEXP_REPLACE(
CONCAT_WS('' -- using concat_ws because concat returns null when one of the fields is null
, day_1
, day_2
-- add more day_n here
, day_31),'[^P]+','')) AS present
FROM YourTable

Answer 2

A more conventional approach might look something like this:
student_id,
attendance_date

Answer 3

You can made a query to get the IDs of all students,
$sql2 = "SELECT distinct id from table";
$query = $this->db->query($sql2);
foreach ($query->result() as $innerrow) {
HERE YOU USE THE SYNTAX OF NEXT CODE-BLOCK
}
Inside the foreach loop you can use the id with $row->id to generate another sql query
with an where clause.
$sql = "SELECT table.* from table where id = ".$row->id;
$query = $this->db->query($sql);
foreach ($query->result() as $row) {
print your data
}

Answer 4

write query to find the attendance with present like
select (if(day_1 in('P'),1,0)+if(day_2 in('P'),1,0)+if(day_3 in('P'),1,0)+if(day_4 in('P'),1,0)+if(day_5 in('P'),1,0)+if(day_6 in('P'),1,0) + if(day_7 in('P'),1,0)+if(day_8 in('P'),1,0)+if(day_9 in('P'),1,0)+....+if(day_n in('P'),1,0)) as day_present from tbl_name
But the if condition for all 31 days or 30 days as per months days
just try it once in your mysql query editor You will get the exact result..
In codeigniter
$result = $this->db->select("(if(day_1 in('P'),1,0)+if(day_2 in('P'),1,0)+if(day_3 in('P'),1,0)+if(day_4 in('P'),1,0)+........+if(day_n in('P'),1,0)) as present, school_id, student_id,year, month, status");
$this->db->get('table_name');