Question

我必须在mysql中创建一个返回整数的函数。 sql解释器一直告诉我，我的语法有问题。我尽我最大的努力看了一遍，尝试了很多东西，但我无法理解。

var arr = [ { id: 1, name: "Hello" }, { id: 2, name: "World" } ];

var data = _.find(arr, { id: 1 }); // => Object {id: 1, name: "Hello"}

var data = _.find(arr, { id: 3 }); // => undefined

错误输出：

CREATE FUNCTION no_of_paintings_exhibited (exhibition_name VARCHAR(45))
RETURNS INT

BEGIN
    DECLARE number_of_paintings INT;

    SELECT
    COUNT(*)
    INTO number_of_paintings
    FROM Exhibition, Shown_at, Painting
    WHERE name = exhibition_name AND Painting.id_no = Shown_at.art;

    RETURN number_of_paintings;

END; //

Answer 1

CREATE FUNCTION no_of_paintings_exhibited (exhibition_name VARCHAR(45))
RETURNS INT

BEGIN
    DECLARE number_of_paintings INT;
set number_of_paintings=0;
    SELECT
    COUNT(*)
    as number_of_paintings
    FROM Exhibition ex, Shown_at shat, Painting ptng
    WHERE ex.name = exhibition_name AND ptng.id_no = shat.art;

    RETURN number_of_paintings;

END;

Answer 2

您收到此错误是因为您没有设置DELIMITER，默认情况下，分号（;）是分隔符，一旦找到它尝试执行的第一个分号并抛出此错误

执行以下操作（在创建函数之前将分隔符设置为$$或//，下面我使用$$）然后再次创建函数后再次将DELIMITER设置为分号。

DELIMITER $$
CREATE FUNCTION ...
..
END;
$$
DELIMITER ;

麻烦mySql功能

2 个答案: