-- ================================================
-- 完整的数据库优化脚本
-- ================================================
-- 功能：
-- 1. 删除冗余索引（提升写入速度）
-- 2. 创建必要索引（提升查询速度）
-- 3. 分析表（更新统计信息）
-- 4. 验证优化结果
-- ================================================

USE study;

SELECT '========================================' AS '';
SELECT '开始执行数据库优化' AS '';
SELECT '========================================' AS '';

-- ================================================
-- 第一步：删除冗余索引
-- ================================================

SELECT '' AS '';
SELECT '【第1步】删除冗余索引...' AS '';

-- 检查 student_class.idx_student_id 是否存在
SELECT CASE 
    WHEN COUNT(*) > 0 THEN '发现冗余索引 idx_student_id，准备删除...'
    ELSE '✅ idx_student_id 不存在，无需删除'
END AS status
FROM information_schema.STATISTICS 
WHERE TABLE_SCHEMA = 'study' 
AND TABLE_NAME = 'student_class' 
AND INDEX_NAME = 'idx_student_id';

-- 删除 student_class.idx_student_id（如果存在）
SET @sql = (SELECT IF(
    (SELECT COUNT(*) FROM information_schema.STATISTICS 
     WHERE TABLE_SCHEMA = 'study' AND TABLE_NAME = 'student_class' 
     AND INDEX_NAME = 'idx_student_id') > 0,
    'ALTER TABLE student_class DROP INDEX idx_student_id',
    'SELECT "idx_student_id 不存在" AS result'
));
PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;

SELECT '✅ 冗余索引删除完成' AS result;

-- ================================================
-- 第二步：创建必要的索引
-- ================================================

SELECT '' AS '';
SELECT '【第2步】创建必要的索引...' AS '';

-- 2.1 sys_user_role.idx_user_id
SELECT '正在检查 sys_user_role.idx_user_id...' AS '';
SET @sql = (SELECT IF(
    (SELECT COUNT(*) FROM information_schema.STATISTICS 
     WHERE TABLE_SCHEMA = 'study' AND TABLE_NAME = 'sys_user_role' 
     AND INDEX_NAME = 'idx_user_id') = 0,
    'ALTER TABLE sys_user_role ADD INDEX idx_user_id (user_id)',
    'SELECT "idx_user_id 已存在，跳过" AS result'
));
PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;

-- 2.2 sys_user_role.idx_role_id
SELECT '正在检查 sys_user_role.idx_role_id...' AS '';
SET @sql = (SELECT IF(
    (SELECT COUNT(*) FROM information_schema.STATISTICS 
     WHERE TABLE_SCHEMA = 'study' AND TABLE_NAME = 'sys_user_role' 
     AND INDEX_NAME = 'idx_role_id') = 0,
    'ALTER TABLE sys_user_role ADD INDEX idx_role_id (role_id)',
    'SELECT "idx_role_id 已存在，跳过" AS result'
));
PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;

-- 2.3 sys_role.idx_del_flag
SELECT '正在检查 sys_role.idx_del_flag...' AS '';
SET @sql = (SELECT IF(
    (SELECT COUNT(*) FROM information_schema.STATISTICS 
     WHERE TABLE_SCHEMA = 'study' AND TABLE_NAME = 'sys_role' 
     AND INDEX_NAME = 'idx_del_flag') = 0,
    'ALTER TABLE sys_role ADD INDEX idx_del_flag (del_flag)',
    'SELECT "idx_del_flag 已存在，跳过" AS result'
));
PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;

-- 2.4 courseware.idx_course_id
SELECT '正在检查 courseware.idx_course_id...' AS '';
SET @sql = (SELECT IF(
    (SELECT COUNT(*) FROM information_schema.STATISTICS 
     WHERE TABLE_SCHEMA = 'study' AND TABLE_NAME = 'courseware' 
     AND INDEX_NAME = 'idx_course_id') = 0,
    'ALTER TABLE courseware ADD INDEX idx_course_id (course_id)',
    'SELECT "idx_course_id 已存在，跳过" AS result'
));
PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;

-- 2.5 learning_detail.idx_student_course
SELECT '正在检查 learning_detail.idx_student_course...' AS '';
SET @sql = (SELECT IF(
    (SELECT COUNT(*) FROM information_schema.STATISTICS 
     WHERE TABLE_SCHEMA = 'study' AND TABLE_NAME = 'learning_detail' 
     AND INDEX_NAME = 'idx_student_course') = 0,
    'ALTER TABLE learning_detail ADD INDEX idx_student_course (student_id, course_id)',
    'SELECT "idx_student_course 已存在，跳过" AS result'
));
PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;

SELECT '✅ 索引创建完成' AS result;

-- ================================================
-- 第三步：分析表（更新统计信息）
-- ================================================

SELECT '' AS '';
SELECT '【第3步】分析表，更新统计信息...' AS '';

ANALYZE TABLE sys_user;
ANALYZE TABLE sys_user_role;
ANALYZE TABLE sys_role;
ANALYZE TABLE student_class;
ANALYZE TABLE courseware;
ANALYZE TABLE learning_detail;

SELECT '✅ 表分析完成' AS result;

-- ================================================
-- 第四步：验证优化结果
-- ================================================

SELECT '' AS '';
SELECT '【第4步】验证优化结果...' AS '';
SELECT '' AS '';

-- 4.1 验证 student_class 冗余索引已删除
SELECT '=== student_class 表索引 ===' AS '';
SELECT CASE 
    WHEN COUNT(*) = 0 THEN '✅ idx_student_id 已成功删除'
    ELSE '❌ idx_student_id 仍然存在！'
END AS '冗余索引检查'
FROM information_schema.STATISTICS 
WHERE TABLE_SCHEMA = 'study' 
AND TABLE_NAME = 'student_class' 
AND INDEX_NAME = 'idx_student_id';

-- 4.2 验证必要索引已创建
SELECT '=== sys_user_role 表索引 ===' AS '';
SELECT 
    CASE WHEN (SELECT COUNT(*) FROM information_schema.STATISTICS 
               WHERE TABLE_SCHEMA = 'study' AND TABLE_NAME = 'sys_user_role' 
               AND INDEX_NAME = 'idx_user_id') > 0 
         THEN '✅' ELSE '❌' END AS 'idx_user_id',
    CASE WHEN (SELECT COUNT(*) FROM information_schema.STATISTICS 
               WHERE TABLE_SCHEMA = 'study' AND TABLE_NAME = 'sys_user_role' 
               AND INDEX_NAME = 'idx_role_id') > 0 
         THEN '✅' ELSE '❌' END AS 'idx_role_id';

SELECT '=== courseware 表索引 ===' AS '';
SELECT 
    CASE WHEN (SELECT COUNT(*) FROM information_schema.STATISTICS 
               WHERE TABLE_SCHEMA = 'study' AND TABLE_NAME = 'courseware' 
               AND INDEX_NAME = 'idx_course_id') > 0 
         THEN '✅' ELSE '❌' END AS 'idx_course_id';

SELECT '=== learning_detail 表索引 ===' AS '';
SELECT 
    CASE WHEN (SELECT COUNT(*) FROM information_schema.STATISTICS 
               WHERE TABLE_SCHEMA = 'study' AND TABLE_NAME = 'learning_detail' 
               AND INDEX_NAME = 'idx_student_course') > 0 
         THEN '✅' ELSE '❌' END AS 'idx_student_course';

-- 4.3 测试查询性能
SELECT '' AS '';
SELECT '=== 查询性能测试 ===' AS '';

-- 测试角色查询
SET @start = NOW(6);
SELECT COUNT(*) INTO @count FROM sys_user_role WHERE user_id = 455;
SET @end = NOW(6);
SELECT 
    TIMESTAMPDIFF(MICROSECOND, @start, @end)/1000 AS '角色查询耗时(ms)',
    CASE 
        WHEN TIMESTAMPDIFF(MICROSECOND, @start, @end)/1000 < 50 THEN '✅ 性能优秀'
        WHEN TIMESTAMPDIFF(MICROSECOND, @start, @end)/1000 < 100 THEN '⚠️ 性能一般'
        ELSE '❌ 性能较差'
    END AS '性能评价';

-- 测试课程查询
SET @start = NOW(6);
SELECT COUNT(*) INTO @count FROM courseware WHERE course_id = 6;
SET @end = NOW(6);
SELECT 
    TIMESTAMPDIFF(MICROSECOND, @start, @end)/1000 AS '课程查询耗时(ms)',
    CASE 
        WHEN TIMESTAMPDIFF(MICROSECOND, @start, @end)/1000 < 50 THEN '✅ 性能优秀'
        WHEN TIMESTAMPDIFF(MICROSECOND, @start, @end)/1000 < 100 THEN '⚠️ 性能一般'
        ELSE '❌ 性能较差'
    END AS '性能评价';

-- 测试学习详情查询
SET @start = NOW(6);
SELECT COUNT(*) INTO @count FROM learning_detail WHERE student_id = 9999 AND course_id = 6;
SET @end = NOW(6);
SELECT 
    TIMESTAMPDIFF(MICROSECOND, @start, @end)/1000 AS '学习详情查询耗时(ms)',
    CASE 
        WHEN TIMESTAMPDIFF(MICROSECOND, @start, @end)/1000 < 50 THEN '✅ 性能优秀'
        WHEN TIMESTAMPDIFF(MICROSECOND, @start, @end)/1000 < 100 THEN '⚠️ 性能一般'
        ELSE '❌ 性能较差'
    END AS '性能评价';

-- ================================================
-- 完成
-- ================================================

SELECT '' AS '';
SELECT '========================================' AS '';
SELECT '✅ 数据库优化完成！' AS '';
SELECT '========================================' AS '';
SELECT '' AS '';
SELECT '下一步操作：' AS '';
SELECT '1. 如果所有索引都是 ✅ 且查询 <50ms → 重启应用服务' AS '';
SELECT '2. 如果有 ❌ 或查询 >100ms → 请联系管理员检查' AS '';
SELECT '3. 重启服务后测试导入速度，应该提升 5-10 倍' AS '';
SELECT '' AS '';