Posted on February 7, 2023 by Kevin Guisarde .

A Comprehensive Guide to SQL Case Statement in Healthcare Industry

The SQL Case Statement is an essential feature of SQL that enables developers and data analysts to build conditional logic into their queries. By evaluating a set of conditions, the Case Statement returns a result that is based on the outcome of the evaluation. This functionality can be used to create complex, multi-level decision trees within a SQL query. With the Case Statement, data analysts can effectively analyze and extract specific data sets from vast data sources, making it an indispensable tool in the data analysis process. Overall, the SQL Case Statement is a powerful feature of SQL that provides developers and data analysts with greater flexibility and precision in their data analysis and decision-making capabilities.

Agenda

1. Introduction to SQL Case Statement
2. Types of SQL Case Statement with examples from the Healthcare Industry
3. Real-World Example Questions in the Healthcare Industry
4. Most Commonly Asked Interview Question and Answer
5. Conclusion

Introduction to SQL Case Statement

SQL Case Statement is a conditional statement in SQL that returns a result based on the evaluation of a set of conditions. The Case Statement is used to implement conditional logic in SQL queries, making it a powerful tool for data analysis and decision-making.

Types of SQL Case Statement with Examples From The Healthcare Industry

Simple Case Statement

A Simple Case Statement is used to evaluate a single expression and return a corresponding result. For example, in the Healthcare Industry, you can use a Simple Case Statement to categorize patients based on their age.

SELECT 
  PatientID, 
  PatientName, 
  Age, 
  CASE 
    WHEN Age < 18 THEN 'Child' 
    WHEN Age BETWEEN 18 AND 64 THEN 'Adult' 
    ELSE 'Senior' 
  END AS PatientCategory 
FROM Patients; 

Searched Case Statement

A Searched Case Statement evaluates multiple conditions and returns a result based on the first matching condition. For example, in the Healthcare Industry, you can use a Searched Case Statement to calculate the co-pay amount for a patient based on their insurance plan.

SELECT 
  PatientID, 
  PatientName, 
  InsurancePlan, 
  CASE 
    WHEN InsurancePlan = 'Plan A' THEN 50 
    WHEN InsurancePlan = 'Plan B' THEN 40 
    ELSE 30 
  END AS CoPayAmount 
  FROM Patients; 

Nested Case Statement

A Nested Case Statement is used to evaluate multiple conditions within another Case Statement. For example, in the Healthcare Industry, you can use a Nested Case Statement to categorize patients based on their age and insurance plan.

SELECT 
  PatientID, 
  PatientName, 
  Age, 
  InsurancePlan, 
  CASE 
    WHEN Age < 18 THEN 'Child' 
    ELSE 
      CASE 
        WHEN InsurancePlan = 'Plan A' THEN 'Adult with Plan A' 
        WHEN InsurancePlan = 'Plan B' THEN 'Adult with Plan B' 
      ELSE 'Senior' 
    END 
  END AS PatientCategory 
FROM Patients; 

Real-World Example Questions in the Healthcare Industry

Script to generate tables and records needed for the real-world example questions:

CREATE TABLE Patients 
( 
  PatientID INT PRIMARY KEY, 
  PatientName VARCHAR(100), 
  Age INT, 
  InsurancePlan VARCHAR(100) 
); 
INSERT INTO Patients (PatientID, PatientName, Age, InsurancePlan) 
VALUES (1, 'John Doe', 35, 'Plan A'), (2, 'Jane Doe', 40, 'Plan B'), (3, 'John Smith', 50, 'Plan C'), (4, 'Jane Smith', 65, 'Plan A'), (5, 'Jim Brown', 25, 'Plan B'); 

1. What is the average age of patients with Plan A and Plan B insurance?

SELECT 
  CASE 
    WHEN insurance_plan = 'Plan A' THEN 'Plan A' 
    WHEN insurance_plan = 'Plan B' THEN 'Plan B' 
  END as Insurance_Plan, 
  AVG(age) as Average_Age 
FROM patients 
GROUP BY insurance_plan 

2. What is the total number of patients for each insurance plan?

SELECT 
  insurance_plan, 
  COUNT(*) as Total_Patients 
FROM patients 
GROUP BY insurance_plan 

3. List the patients and their age categories (Child, Adult with Plan A, Adult with Plan B, Senior) based on their age and insurance plan.

SELECT 
  patient_name, 
  age, 
  insurance_plan, 
  CASE WHEN age <= 18 THEN 'Child' 
    WHEN age BETWEEN 18 and 65 AND insurance_plan = 'Plan A' THEN 'Adult with Plan A'           
    WHEN age BETWEEN 18 and 65 AND insurance_plan = 'Plan B' THEN 'Adult with Plan B' 
    WHEN age > 65 THEN 'Senior' 
  END as Age_Category 
FROM patients

Most Commonly Asked Interview Question and Answer

Q: How do you use the SQL Case Statement in a real-world scenario?

A: I have used the SQL Case Statement in several real-world projects, including in the Healthcare Industry. One specific example is when I was working on a project to categorize patients based on their age and insurance plan. To accomplish this, I used a Nested Case Statement that evaluated the patient’s age and insurance plan and returned the appropriate patient category. The final result was a table that displayed the patient’s information, including their age category, which was used for further analysis and decision-making. The use of the Case Statement made the process of categorizing patients much simpler and more efficient.

Conclusion

The SQL Case Statement is a versatile and powerful tool for data analysis and decision-making in SQL. With the different types of Case Statements, including Simple, Searched, and Nested, you can implement complex conditional logic and return results based on multiple evaluations. By using examples from the Healthcare Industry, you can see the practical applications of the Case Statement and how it can be used to improve your data analysis and decision-making processes.