MySQL INSERT 在 CASE 中作为子查询

Question

我遇到以下情况，我想仅使用 MySQL 来完成。

CASE 'some_boolean'
(
  WHEN true THEN
     //COMPLEX INSERT HERE
  WHEN FALSE THEN
     //DIFFERENT COMPLEX INSERT HERE
)
END

我知道我可以使用 PHP 来做到这一点，但代码会变得困惑，所以我更喜欢使用 MySQL，但我不知道语法应该如何，或者是否可以做到这一点。

谢谢:)

编辑:我所说的复杂是指它从 SELECT 中获取插入数据。

编辑2:这是我试图详细说明的 SQL。它有一些标有“:”的 PHP 输入。

CASE (SELECT IF(COUNT(*) > 0,true,false) AS structure FROM structures WHERE product_number = "123")
    WHEN true THEN
        INSERT INTO product_balance (product_number,balance)
        (
            SELECT :product_number, product_count * :order_count FROM structures WHERE product_number = :product_number
        )
        ON DUPLICATE KEY UPDATE balance = balance + (product_count * :order_count)
    ELSE
        INSERT INTO product_balance (product_number,balance)
        VALUES(:product_number,:order_count)
        ON DUPLICATE KEY UPDATE balance = balance + (product_count * :order_count)
END

Answer 1

语法:

IF condition1 THEN
   {...statements to execute when condition1 is TRUE...}

[ ELSEIF condition2 THEN
   {...statements to execute when condition2 is TRUE...} ]

[ ELSE
   {...statements to execute when both condition1 and condition2 are FALSE...} ]

END IF;

示例:

DELIMITER //  
CREATE FUNCTION IncomeLevel ( monthly_value INT )
RETURNS varchar(20)\

BEGIN
   DECLARE income_level varchar(20);

   IF monthly_value <= 4000 THEN
      SET income_level = 'Low Income';
   ELSEIF monthly_value > 4000 AND monthly_value <= 7000 THEN
      SET income_level = 'Avg Income';
   ELSE
      SET income_level = 'High Income';
   END IF;

   RETURN income_level;
END; //

DELIMITER ;

来源:http://www.techonthenet.com/mysql/loops/if_then.php