mysql - MySQL代码中END关键字的语法错误问题

Question

当一切看起来都很好时，为什么我会收到语法错误。指出了 MySQL 工作台上的错误位置。我检查了很多问题，但没有找到答案。我知道这将是一个小问题，但我无法弄清楚

SELECT * FROM classicmodels.customers;


DELIMITER $$

create function CustomerLevel( credit decimal(10,2))

returns varchar(20) deterministic
begin 
    
    declare customerLevel varchar(20);
    
    if (credit > 50000) then set customerLevel = 'PLATINUM';
 
       else if (credit >= 50000 and credit <= 10000) then set customerLevel = 'GOLD';
    
    else IF (credit < 10000) then set customerLevel ='SILVER';
    
    end if;
    
    return (customerLevel);
 
end; -- this is where the syntax error code is
 $$ DELIMITER ;
 
 

/* 
Error Code: 1064. 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 '' at line 10
 */
```````````````