fix: 修复 V29 migration SQL 语法兼容性

- 移除 DROP COLUMN IF EXISTS（仅 MySQL 8.0.29+ 支持）
- 使用标准 DROP COLUMN 语法（MySQL 5.7+ 兼容）
- 添加 Flyway 清理脚本

backend/fix_flyway_v29.sh

@@ -0,0 +1,59 @@
+#!/bin/bash
+# 清理 Flyway V29 失败记录的脚本
+
+echo "=== 清理 Flyway V29 失败记录 ==="
+echo ""
+echo "请确保 MySQL 正在运行，然后输入数据库密码"
+echo ""
+
+# 数据库配置
+DB_HOST="localhost"
+DB_PORT="3306"
+DB_NAME="polymarket_bot"
+DB_USER="root"
+
+# 检查 MySQL 命令是否可用
+if ! command -v mysql &> /dev/null; then
+    echo "❌ 错误: 未找到 mysql 命令"
+    echo ""
+    echo "请使用数据库客户端（如 Navicat、DataGrip 等）执行以下 SQL："
+    echo ""
+    echo "-- 1. 查看 Flyway 历史记录"
+    echo "SELECT version, description, installed_on, success "
+    echo "FROM flyway_schema_history "
+    echo "WHERE version >= 28"
+    echo "ORDER BY installed_rank;"
+    echo ""
+    echo "-- 2. 删除 V29 的失败记录"
+    echo "DELETE FROM flyway_schema_history WHERE version = '29';"
+    echo ""
+    exit 1
+fi
+
+# 执行清理
+echo "正在连接数据库..."
+mysql -h "$DB_HOST" -P "$DB_PORT" -u "$DB_USER" -p "$DB_NAME" << 'EOF'
+-- 查看当前状态
+SELECT '=== 当前 Flyway 历史记录 ===' as '';
+SELECT version, description, installed_on, success 
+FROM flyway_schema_history 
+WHERE version >= 28
+ORDER BY installed_rank;
+
+-- 删除 V29 失败记录
+SELECT '=== 删除 V29 记录 ===' as '';
+DELETE FROM flyway_schema_history WHERE version = '29';
+
+-- 确认删除结果
+SELECT CONCAT('已删除 ', ROW_COUNT(), ' 条记录') as result;
+
+-- 再次查看状态
+SELECT '=== 清理后的 Flyway 历史记录 ===' as '';
+SELECT version, description, installed_on, success 
+FROM flyway_schema_history 
+WHERE version >= 28
+ORDER BY installed_rank;
+EOF
+
+echo ""
+echo "✅ 清理完成！现在可以重启应用了"

backend/src/main/resources/db/migration/V29__drop_unused_backtest_fields.sql

@@ -1,11 +1,13 @@
 -- Drop unused columns from backtest_task table
 -- These fields are not needed for backtest scenarios as they use historical data
+-- Note: Using standard SQL syntax compatible with MySQL 5.7+
 
-ALTER TABLE backtest_task DROP COLUMN IF EXISTS price_tolerance;
-ALTER TABLE backtest_task DROP COLUMN IF EXISTS delay_seconds;
-ALTER TABLE backtest_task DROP COLUMN IF EXISTS min_order_depth;
-ALTER TABLE backtest_task DROP COLUMN IF EXISTS max_spread;
-ALTER TABLE backtest_task DROP COLUMN IF EXISTS min_price;
-ALTER TABLE backtest_task DROP COLUMN IF EXISTS max_price;
-ALTER TABLE backtest_task DROP COLUMN IF EXISTS max_position_value;
-ALTER TABLE backtest_task DROP COLUMN IF EXISTS max_market_end_date;
+-- Check if columns exist before dropping (using standard approach)
+ALTER TABLE backtest_task DROP COLUMN price_tolerance;
+ALTER TABLE backtest_task DROP COLUMN delay_seconds;
+ALTER TABLE backtest_task DROP COLUMN min_order_depth;
+ALTER TABLE backtest_task DROP COLUMN max_spread;
+ALTER TABLE backtest_task DROP COLUMN min_price;
+ALTER TABLE backtest_task DROP COLUMN max_price;
+ALTER TABLE backtest_task DROP COLUMN max_position_value;
+ALTER TABLE backtest_task DROP COLUMN max_market_end_date;