Unable to import MYSQL function - ERROR 1064 (42000)

Question

I'm trying to understand why the following is failing and I'm not able to see it. The phpMyAdmin on our development server generated this exactly, but when I try importing it - I'm running into a weird parsing(?) error.

mysql> DELIMITER $$
mysql>
mysql> --
mysql> -- Functions
mysql> --
mysql> DROP FUNCTION IF EXISTS `get_class_nextsession`$$
Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql> CREATE DEFINER=`myusername`@`localhost` FUNCTION `get_class_nextsession`(class_id INT) RETURNS datetime
    ->     READS SQL DATA
    -> BEGIN
    -> DECLARE nextsession,startdate,runningdate,enddate DATETIME;
    -> SET nextsession= '-';
    -> SELECT  MIN(CS.start_datetime) INTO startdate FROM site_class_schedule AS CS INNER JOIN site_class AS C ON (C.id=CS.class_id) WHERE CS.class_id=class_id Group by C.id Limit 0,1;
    -> IF startdate >= NOW() THEN
    -> RETURN startdate;
    -> ELSE
    -> SELECT  CS.start_datetime INTO runningdate FROM site_class_schedule AS CS INNER JOIN site_class AS C ON (C.id=CS.class_id) WHERE CS.class_id=class_id and (NOW() between start_datetime and end_datetime ) Limit 0,1;
    -> IF runningdate IS NOT NULL THEN
    -> RETURN runningdate;
    -> ELSE
    -> SELECT  MAX(CS.end_datetime) INTO enddate FROM site_class_schedule AS CS INNER JOIN site_class AS C ON (C.id=CS.class_id) WHERE CS.class_id=class_id Group by C.id Limit 0,1;
    -> IF enddate < NOW() THEN
    -> RETURN enddate;
    -> ELSEIF enddate >= NOW() THEN
    -> SELECT  MIN(CS.start_datetime) INTO startdate FROM site_class_schedule AS CS INNER JOIN site_class AS C ON (C.id=CS.class_id) WHERE CS.class_id=class_id and CS.start_datetime > NOW() Group by C.id Limit 0,1;
    ->
Display all 1866 possibilities? (y or n)
    ->  startdate;
    ->
Display all 1866 possibilities? (y or n)
    -> D IF;
    -> END IF;
    -> END IF;
    -> RETURN nextsession;
    -> END$$
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ';
D IF;
END IF;
END IF;
RETURN nextsession;
END' at line 19
mysql>
mysql>

---

Progress Update 1

This WORKED

mysql> DELIMITER $$
mysql>
mysql> DROP FUNCTION IF EXISTS `get_class_nextsession`$$
Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql> CREATE DEFINER=`myusername`@`localhost` FUNCTION `get_class_nextsession`(class_id INT) RETURNS datetime
    ->     READS SQL DATA
    -> BEGIN
    -> RETURN nextsession;
    -> END$$
Query OK, 0 rows affected (0.00 sec)

This WORKED

mysql>
mysql> DROP FUNCTION IF EXISTS `get_class_nextsession`$$
Query OK, 0 rows affected (0.00 sec)

mysql>
mysql> CREATE DEFINER=`myusername`@`localhost` FUNCTION `get_class_nextsession`(class_id INT) RETURNS datetime
    ->     READS SQL DATA
    -> BEGIN
    -> DECLARE nextsession,startdate,runningdate,enddate DATETIME;
    -> RETURN nextsession;
    -> END$$
Query OK, 0 rows affected (0.00 sec)

This did NOT WORK - Notice how I'm trying to simplify the query / statements into basic ones.

mysql> DROP FUNCTION IF EXISTS `get_class_nextsession`$$
Query OK, 0 rows affected, 1 warning (0.01 sec)

mysql> CREATE DEFINER=`myusername`@`localhost` FUNCTION `get_class_nextsession`(class_id INT) RETURNS datetime
    ->     READS SQL DATA
    -> BEGIN
    -> DECLARE nextsession,startdate,runningdate,enddate DATETIME;
    -> SET nextsession= '-';
    -> SELECT  MIN(start_datetime) INTO startdate FROM site_class_schedule;
    -> IF startdate >= NOW() THEN
    -> RETURN startdate;
    -> ELSE
    -> END IF;
    -> RETURN nextsession;
    -> END$$
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'END IF;
RETURN nextsession;
END' at line 10

Answer 1

Ah ha!

Definitely an 'unusual' error wherein 'nothing' was wrong! The problems I was facing was due to excessive tabs being generated or placed in the original FUNCTION creation! The two consecutive \t s were breaking the flow of data input on the mysql prompt and having mysql ask

 Display all 1866 possibilities? (y or n)

Moreover, when I was copy pasting here on SO, I was pasting the final output of my interaction with the MYSQL command prompt, not what I had actually placed 'in' there!

DROP FUNCTION IF EXISTS `get_class_nextsession`$$
CREATE DEFINER=`myusername`@`localhost` FUNCTION `get_class_nextsession`(class_id INT) RETURNS datetime
    READS SQL DATA
BEGIN
DECLARE nextsession,startdate,runningdate,enddate DATETIME;
SET nextsession= '-';
SELECT  MIN(CS.start_datetime) INTO startdate FROM site_class_schedule AS CS INNER JOIN site_class AS C ON (C.id=CS.class_id) WHERE CS.class_id=class_id Group by C.id Limit 0,1;
IF startdate >= NOW() THEN
RETURN startdate;
ELSE    
SELECT  CS.start_datetime INTO runningdate FROM site_class_schedule AS CS INNER JOIN site_class AS C ON (C.id=CS.class_id) WHERE CS.class_id=class_id and (NOW() between start_datetime and end_datetime ) Limit 0,1;
IF runningdate IS NOT NULL THEN
RETURN runningdate;
ELSE
SELECT  MAX(CS.end_datetime) INTO enddate FROM site_class_schedule AS CS INNER JOIN site_class AS C ON (C.id=CS.class_id) WHERE CS.class_id=class_id Group by C.id Limit 0,1;
IF enddate < NOW() THEN
    RETURN enddate;
ELSEIF enddate >= NOW() THEN
SELECT  MIN(CS.start_datetime) INTO startdate FROM site_class_schedule AS CS INNER JOIN site_class AS C ON (C.id=CS.class_id) WHERE CS.class_id=class_id and CS.start_datetime > NOW() Group by C.id Limit 0,1;
            RETURN startdate; ****ISSUE WITH MORE THAN 2 TABS****
        END IF; ****ISSUE WITH MORE THAN 2 TABS****
    END IF;
END IF;
RETURN nextsession;
END$$