Question

I am trying to make a query in Codeigniter that will allow a user to retrieve a record they submitted in the past to my database.

This is my schema:

https://i.stack.imgur.com/zSHSQ.png

I am having trouble figuring out what I need to do for some of my tables

For example 1:M or M:M

1. 1 procedure has 1 or many procedure_event
2. a procedure_event may or may not have use resources
3. 1 procedure has 1 or many staff

I think I need to use Select, Joins for this and I have got some of it completed but for the Many to Many relationships and linked tables I am confused how to do them.

This is what I have got so far in terms of code but it is not returning any rows so I think it is wrong:

    public function view_record($record_id)
    {
        //The criteria used for WHERE is a variable with array of procedure_id = record_id that is passed to function
        $criteria = array 
        (
            'procedure_id' => $record_id
        );

        //this selects the columns from procedure table for use in joins 
        $this->db->select('procedure.procedure_id, procedure.patient_id, procedure.department_id, procedure.name_id , procedure.dosage_id');
        //this is the table I want to use the columns from
        $this->db->from ('procedure');

        //this joins the patient row that matches its ID to the patient ID in the procedure table
        $this->db->join('patient', 'patient.patient_id = procedure.patient_id', 'inner');

        //this joins the department row that matches its ID to the patient ID in the procedure table
        $this->db->join('department', 'department.department_id = procedure.department_id', 'inner');

        //this joins the procedure_name row that matches its ID to the patient ID in the procedure table
        $this->db->join('procedure_name', 'procedure_name.procedure_name_id = procedure.name_id', 'inner');

        //this joins the dosage row that matches its ID to the patient ID in the procedure table
        $this->db->join('dosage', 'dosage.dosage_id = procedure.dosage_id', 'inner');

        //this selects the row in procedure table that matches the record number
        $this->db->where('procedure_id', $record_id);

        /*
        Code for other tables:
        I need help with

        procedure_event, staff, resources, hr

        */

        //this part I think is wrong
        $result = $this->db->get();


        //
        if ($result->num_rows >0)
        {
            echo "There is Data!";

        }

        else
        {
            echo "No Data!";

        }

}

I get back a message saying “No Records” however there is data in my tables etc:

So my query so far must be wrong.

Thanks for your time!

Answer 1

Firstly, I personally consider it easier to write as complex queries as this on in pure text, rather then using Active Records.

All your joins uses inner; that is that all rows need to find a partner in the other table. If any of these doesn’t exist you get 0 rows. Consider using LEFT JOIN, as previously suggested.

Do all of these tables contain data at the moment?

Do need absolutely a partner row in everyone of these tables, or do you count on cases where rows are missing?