Question

我试图找出插入使用mysql中的条件语句，如INSERT INTO in a CASE statement

SET @foo = 1
SELECT (CASE WHEN 1 THEN (
  INSERT INTO table1 (`id`, `column`) VALUE (1, 'a');
  SET @bar = SELECT LAST_INSERT_ID();
  UPDATE table2 SET c1 = @foo WHERE c2 = @bar
) END)

我按照How do write IF ELSE statement in a MySQL query

的建议使用case

但是当我试着继续这样做时：

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 'INTO ForgeRock (`id`, `productName`, `description`) VALUE (4, 'a','b') ) END)' at line 2

http://sqlfiddle.com/#!9/dcb16/22063

所以我试图采用if / else方法...

SELECT IF(1,(INSERT INTO ForgeRock (`id`, `productName`, `description`) VALUE (4, 'a','b')),0)

但是这会产生同样的错误

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 'INTO ForgeRock (`id`, `productName`, `description`) VALUE (4, 'a','b')),0)' at line 1

http://sqlfiddle.com/#!9/dcb16/22081

所以我假设在mysql中无法做到这一点？ https://stackoverflow.com/a/13681306/1267259 （但OP没有得到同样的错误？）

当我写这个问题时，我发现Using IF ELSE statement based on Count to execute different Insert statements 是使用程序执行此操作的唯一方法吗？

Answer 1

请记住IF() function和IF statement之间的区别。

您可以实现的一个选项是使用FUNCTION（13.1.12 CREATE PROCEDURE and CREATE FUNCTION Syntax）：

/* CODE FOR DEMONSTRATION PURPOSES */

DELIMITER //

CREATE FUNCTION `insert_new_value` (`p_foo` INT UNSIGNED) RETURNS TINYINT(1)
DETERMINISTIC
BEGIN
  /*
  INSERT INTO table1 (`id`, `column`) VALUE (1, 'a');
  SET @bar = SELECT LAST_INSERT_ID();
  -- UPDATE table2 SET c1 = @foo WHERE c2 = @bar;
  UPDATE table2 SET c1 = `p_foo` WHERE c2 = @bar;
  */
  INSERT INTO `ForgeRock`
  (`id`, `productName`, `description`)
  VALUES
  (4, 'a', 'b');
  RETURN 1;
END//

DELIMITER ;

SET @foo := 1;
-- You can also use CASE expression.
SELECT IF(1, `insert_new_value`(@foo), 0) INTO @`return_value`;

/* CODE FOR DEMONSTRATION PURPOSES */

SQL Fiddle demo

mysql在条件语句中查询INSERT INTO（如果是/ else则为case）

1 个答案: