a SQL query for codeigniter project [closed] - mysql

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In my codeigniter project, User enter course code and regional center by using drop downs. According to this both data, system should calculate total income of the last 3 years for relevant course code AND regional center.
As an example,
In “budget” table, course code-ABC1123 and Perth regional center has 4 data. The system should find the latest 3 years of income for the "Sum of income" column. The course code and regional center are selected by user.
Could you please tell me the SQL query for the above mentioned statement using CodeIgniter?

Answer 1

select sum(income)
from budget
where code = ? and center = ?
and year > (
select max(year) - 3
from budget
where code = ? and center = ?
)
The inner query gets the latest year for code & center and then subtracts 3. And the outer query then sums up all incomes for code & center for years that are greater than this calculated year, so for the last 3 years.
For CodeIgniter3 this would be:
$this->db->query(
'select sum(income)
from budget
where code = ? and center = ?
and year > (
select max(year) - 3
from budget
where code = ? and center = ?
)', array($code, $center, $code, $center)); // ->row() or ->row_array()
And for CodeIgniter4 use $db->query(...) instead of $this->db->query(...).