fix(user): modify SQL migration scripts to add columns only if they do not exist

initialize/migrate/database/02115_ads.up.sql

@@ -1,2 +1,2 @@
 ALTER TABLE `ads`
-    ADD COLUMN `description` VARCHAR(255) DEFAULT '' COMMENT 'Description';
+    MODIFY COLUMN `description` VARCHAR(255) DEFAULT '' COMMENT 'Description';

initialize/migrate/database/02116_user_algo.down.sql

@@ -1,3 +1,3 @@
-ALTER TABLE `User`
+ALTER TABLE `user`
 DROP COLUMN `algo`,
     DROP COLUMN `salt`;

initialize/migrate/database/02116_user_algo.up.sql

@@ -1,3 +1,35 @@
-ALTER TABLE `User`
-    ADD COLUMN IF NOT EXISTS `algo` VARCHAR(20) NOT NULL DEFAULT 'default' COMMENT 'Encryption Algorithm' AFTER `password`,
-    ADD COLUMN IF NOT EXISTS `salt` VARCHAR(20) NOT NULL DEFAULT 'default' COMMENT 'Password Salt' AFTER `algo`;
+-- 添加 algo 列（如果不存在）
+SET @dbname = DATABASE();
+SET @tablename = 'user';
+SET @colname = 'algo';
+SET @sql = (
+    SELECT IF(
+        COUNT(*) = 0,
+        'ALTER TABLE `user` ADD COLUMN `algo` VARCHAR(20) NOT NULL DEFAULT ''default'' COMMENT ''Encryption Algorithm'' AFTER `password`;',
+        'SELECT "Column `algo` already exists";'
+    )
+    FROM information_schema.COLUMNS
+    WHERE TABLE_SCHEMA = @dbname
+      AND TABLE_NAME = @tablename
+      AND COLUMN_NAME = @colname
+);
+PREPARE stmt FROM @sql;
+EXECUTE stmt;
+DEALLOCATE PREPARE stmt;
+
+-- 添加 salt 列（如果不存在）
+SET @colname = 'salt';
+SET @sql = (
+    SELECT IF(
+        COUNT(*) = 0,
+        'ALTER TABLE `User` ADD COLUMN `salt` VARCHAR(20) NOT NULL DEFAULT ''default'' COMMENT ''Password Salt'' AFTER `algo`;',
+        'SELECT "Column `salt` already exists";'
+    )
+    FROM information_schema.COLUMNS
+    WHERE TABLE_SCHEMA = @dbname
+      AND TABLE_NAME = @tablename
+      AND COLUMN_NAME = @colname
+);
+PREPARE stmt FROM @sql;
+EXECUTE stmt;
+DEALLOCATE PREPARE stmt;