patients-with-a-condition.sql

/*

Description
LeetCode Problem 1527.

Table: Patients

+--------------+---------+
| Column Name  | Type    |
+--------------+---------+
| patient_id   | int     |
| patient_name | varchar |
| conditions   | varchar |
+--------------+---------+
patient_id is the primary key for this table.
'conditions' contains 0 or more code separated by spaces. 
This table contains information of the patients in the hospital.
Write an SQL query to report the patient_id, patient_name all conditions of patients who have Type I Diabetes. Type I Diabetes always starts with DIAB1 prefix

Return the result table in any order.

The query result format is in the following example.

Patients
+------------+--------------+--------------+
| patient_id | patient_name | conditions   |
+------------+--------------+--------------+
| 1          | Daniel       | YFEV COUGH   |
| 2          | Alice        |              |
| 3          | Bob          | DIAB100 MYOP |
| 4          | George       | ACNE DIAB100 |
| 5          | Alain        | DIAB201      |
+------------+--------------+--------------+

Result table:
+------------+--------------+--------------+
| patient_id | patient_name | conditions   |
+------------+--------------+--------------+
| 3          | Bob          | DIAB100 MYOP |
| 4          | George       | ACNE DIAB100 | 
+------------+--------------+--------------+
Bob and George both have a condition that starts with DI

*/


# V0
select patient_id, patient_name, conditions
from Patients
where conditions like "%DIAB1%"

# V1
# https://circlecoder.com/patients-with-a-condition/
select patient_id, patient_name, conditions
from Patients
where conditions like "%DIAB1%"

# V2
# Time:  O(n)
# Space: O(n)
SELECT * 
FROM Patients AS p
WHERE p.conditions REGEXP '^DIAB1| DIAB1';