MySQL是一款常用的關系型數據庫管理系統，而測試用例則是測試數據庫性能和功能的重要手段。下面將介紹如何寫MySQL測試用例。

-- 第一步，準備測試數據
CREATE TABLE `student` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(50) NOT NULL,
`age` int(11) NOT NULL,
`score` int(11) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;
INSERT INTO `student` (`name`, `age`, `score`) VALUES ('張三', 18, 90);
INSERT INTO `student` (`name`, `age`, `score`) VALUES ('李四', 19, 85);
INSERT INTO `student` (`name`, `age`, `score`) VALUES ('王五', 20, 88);
-- 第二步，編寫測試用例
-- 定義測試用例模塊
CREATE PROCEDURE `test_get_student` ()
BEGIN
DECLARE result INT;
DECLARE expected INT;
-- 測試用例1：查詢單個學生數據
SELECT score INTO result FROM student WHERE name = '張三';
SET expected = 90;
IF result = expected THEN
SELECT "Test case 1 passed.";
ELSE
SELECT "Test case 1 failed.";
END IF;
-- 測試用例2：查詢年齡在20歲以下的學生數量
SELECT COUNT(*) INTO result FROM student WHERE age< 20;
SET expected = 2;
IF result = expected THEN
SELECT "Test case 2 passed.";
ELSE
SELECT "Test case 2 failed.";
END IF;
-- 測試用例3：更新學生數據
UPDATE student SET score = 95 WHERE name = '李四';
SELECT score INTO result FROM student WHERE name = '李四';
SET expected = 95;
IF result = expected THEN
SELECT "Test case 3 passed.";
ELSE
SELECT "Test case 3 failed.";
END IF;
-- 測試用例4：刪除學生數據
DELETE FROM student WHERE name = '王五';
SELECT COUNT(*) INTO result FROM student WHERE name = '王五';
SET expected = 0;
IF result = expected THEN
SELECT "Test case 4 passed.";
ELSE
SELECT "Test case 4 failed.";
END IF;
END;
-- 第三步，運行測試用例
CALL test_get_student();

以上測試用例包括查詢、更新和刪除學生數據的測試，通過比較結果和期望值的方法驗證是否正確。在寫測試用例時，需要明確測試目標、輸入參數和預期結果，并對多種情況進行充分測試，保證數據庫的性能和功能。