选择列条目作为一个字符串

Question

I have table like this:

CREATE TABLE IF NOT EXISTS `test` (
    `a` int(11) NOT NULL,
    `b` int(11) NOT NULL,
    `c` int(11) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;

INSERT INTO `test` (`a`, `b`, `c`) VALUES
(1, 2, 3),
(4, 5, 6),
(7, 8, 9),
(10, 11, 12),
(13, 14, 15);

Which statement would be get out a string like this "1,4,7,10,13"? I don't understand what one of contact functions i need, and how to use it right, i get anytime errors or wrong strings

Answer 1

You could use GROUP_CONCAT() . In this example, this would work. Obviously you would probably need add a WHERE clause to it.

SELECT GROUP_CONCAT(a)

FROM   test

Also if you wanted to do this for multiple groups you would want to use a GROUP BY clause.

Answer 2

试试GROUP_CONCAT

SELECT GROUP_CONCAT(a) FROM test;

Answer 3

What you're looking for is the function: GROUP_CONCAT

SELECT GROUP_CONCAT(a) AS result_list
FROM test