MySQL select query Error

Question

My query is throwing an error like

select id,cHospital from med_patient where cHospital is not null  union
select id,cHospital1 from med_patient where cHospital1 is not null  union
select id,cHospital2 from med_patient where cHospital2 is not null  order by 1

The error is

Notice: Undefined index: cHospital1 in F:\wamp\www\mmr-final\admin\all_hospital_list.php on line 97

Notice: Undefined index: cHospital2 in F:\wamp\www\mmr-final\admin\all_hospital_list.php on line 98

Notice: Undefined index: cHospital1 in F:\wamp\www\mmr-final\admin\all_hospital_list.php on line 97

Notice: Undefined index: cHospital2 in F:\wamp\www\mmr-final\admin\all_hospital_list.php on line 98

Notice: Undefined index: cHospital1 in F:\wamp\www\mmr-final\admin\all_hospital_list.php on line 97

Notice: Undefined index: cHospital2 in F:\wamp\www\mmr-final\admin\all_hospital_list.php on line 98

Notice: Undefined index: cHospital1 in F:\wamp\www\mmr-final\admin\all_hospital_list.php on line 97

Notice: Undefined index: cHospital2 in F:\wamp\www\mmr-final\admin\all_hospital_list.php on line 98

Notice: Undefined index: cHospital1 in F:\wamp\www\mmr-final\admin\all_hospital_list.php on line 97

Notice: Undefined index: cHospital2 in F:\wamp\www\mmr-final\admin\all_hospital_list.php on line 98

Notice: Undefined index: cHospital1 in F:\wamp\www\mmr-final\admin\all_hospital_list.php on line 97

Notice: Undefined index: cHospital2 in F:\wamp\www\mmr-final\admin\all_hospital_list.php on line 98`

And also it's throwing Null row.

How can this query be changed to not cause an error?

Answer 1

Those are not MySQL errors. They are PHP errors. Basically you are most likely attempting to use variables without declaring them first. Be sure to always declare your variables before using them. It makes you less like to have errors.