Using CASE Statement in Stored Function MySQL

Question

I am creating a stored function in MYSQL Workbench that takes a date and returns the quarter of that fiscal year. I came up with the following code script. The SQL Editor checked the statements and accepted this function has no syntax errors.

CREATE  FUNCTION `get_fiscal_quarter`(calendar_date DATE) RETURNS char(2) 
    DETERMINISTIC
BEGIN
      DECLARE quart CHAR(2); 
      DECLARE quar CHAR(2);
      SELECT CASE 
          WHEN MONTH(calendar_date) IN (9,10,11) THEN  quart = 'Q1'
          WHEN MONTH(calendar_date) IN (12,1,2) THEN  quart = 'Q2'
          WHEN MONTH(calendar_date) IN (3,4,5) THEN  quart = 'Q3'
          WHEN MONTH(calendar_date) IN (6,7,8) THEN  quart = 'Q4'
          END 
     INTO quar; 
RETURN quar;
END

But when I tried to applying the get_fiscal_quarter function on a date value, it is returning NULL . Where am I doing wrong?

I tried using the IF Statement but ran into many errors related to delimiters.

Statement is incomplete, expecting IF

Statement is incomplete, expecting END

delimiter is not valid at this position, expecting CREATE

I understood that MySQL Workbench script editor is automatically applying the delimiters code when I clicked the apply and so not accepting manually giving the DELIMITER $$ . But due to this, I'm getting this infinite loop of statement is incomplete syntax errors when I tried to use ; delimiter and END the CASE/IF . I declared 2 variables to use in CASE statement to escape these errors. But didn't get the expected result.

What is the correct way to write CASE and IF statements to create the stored functions in the MySQL WorkBench? It's so confusing to figure out the bug?

Answer 1

CREATE FUNCTION `get_fiscal_quarter`(calendar_date DATE) 
RETURNS char(2) 
DETERMINISTIC
RETURN CASE WHEN MONTH(calendar_date) IN (9,10,11) THEN  'Q1'
            WHEN MONTH(calendar_date) IN (12,1,2)  THEN  'Q2'
            WHEN MONTH(calendar_date) IN (3,4,5)   THEN  'Q3'
            WHEN MONTH(calendar_date) IN (6,7,8)   THEN  'Q4'
            END;