修复迁移时,数据库未指定的情况下数据库脚本混乱的问题

migration/migration.go

@@ -26,6 +26,7 @@ type Migrator struct {
 	db         *gorm.DB
 	migrations []Migration
 	tableName  string
+	dbType     string // 数据库类型: mysql, postgres, sqlite
 }
 
 // NewMigrator 创建新的迁移器
@@ -41,6 +42,25 @@ func NewMigrator(db *gorm.DB, tableName ...string) *Migrator {
 		db:         db,
 		migrations: make([]Migration, 0),
 		tableName:  table,
+		dbType:     "", // 未指定时为空，会使用兼容模式
+	}
+}
+
+// NewMigratorWithType 创建新的迁移器（指定数据库类型，性能更好）
+// db: GORM数据库连接
+// dbType: 数据库类型 ("mysql", "postgres", "sqlite")
+// tableName: 存储迁移记录的表名，默认为 "schema_migrations"
+func NewMigratorWithType(db *gorm.DB, dbType string, tableName ...string) *Migrator {
+	table := "schema_migrations"
+	if len(tableName) > 0 && tableName[0] != "" {
+		table = tableName[0]
+	}
+
+	return &Migrator{
+		db:         db,
+		migrations: make([]Migration, 0),
+		tableName:  table,
+		dbType:     dbType,
 	}
 }
 
@@ -56,18 +76,78 @@ func (m *Migrator) AddMigrations(migrations ...Migration) {
 
 // initTable 初始化迁移记录表
 func (m *Migrator) initTable() error {
-	// 检查表是否存在
+	// 检查表是否存在（根据数据库类型使用对应的SQL，性能更好）
 	var exists bool
-	err := m.db.Raw(fmt.Sprintf(`
-		SELECT EXISTS (
-			SELECT FROM information_schema.tables 
-			WHERE table_schema = CURRENT_SCHEMA() 
-			AND table_name = '%s'
-		)
-	`, m.tableName)).Scan(&exists).Error
+	var err error
 
+	switch m.dbType {
+	case "mysql":
+		// MySQL/MariaDB语法
+		var count int64
+		err = m.db.Raw(fmt.Sprintf(`
+			SELECT COUNT(*) FROM information_schema.tables 
+			WHERE table_schema = DATABASE() 
+			AND table_name = '%s'
+		`, m.tableName)).Scan(&count).Error
+		if err == nil {
+			exists = count > 0
+		}
+	case "postgres":
+		// PostgreSQL语法
+		err = m.db.Raw(fmt.Sprintf(`
+			SELECT EXISTS (
+				SELECT 1 FROM information_schema.tables 
+				WHERE table_schema = CURRENT_SCHEMA() 
+				AND table_name = '%s'
+			)
+		`, m.tableName)).Scan(&exists).Error
+	case "sqlite":
+		// SQLite语法
+		var count int64
+		err = m.db.Raw(fmt.Sprintf(`
+			SELECT COUNT(*) FROM sqlite_master 
+			WHERE type='table' AND name='%s'
+		`, m.tableName)).Scan(&count).Error
+		if err == nil {
+			exists = count > 0
+		}
+	default:
+		// 未指定数据库类型时，使用兼容模式（向后兼容）
+		// 按顺序尝试不同数据库的语法
+		var count int64
+		err = m.db.Raw(fmt.Sprintf(`
+			SELECT COUNT(*) FROM information_schema.tables 
+			WHERE table_schema = DATABASE() 
+			AND table_name = '%s'
+		`, m.tableName)).Scan(&count).Error
+		if err == nil && count > 0 {
+			exists = true
+		} else {
+			var pgExists bool
+			err = m.db.Raw(fmt.Sprintf(`
+				SELECT EXISTS (
+					SELECT 1 FROM information_schema.tables 
+					WHERE table_schema = CURRENT_SCHEMA() 
+					AND table_name = '%s'
+				)
+			`, m.tableName)).Scan(&pgExists).Error
+			if err == nil {
+				exists = pgExists
+			} else {
+				var sqliteCount int64
+				err = m.db.Raw(fmt.Sprintf(`
+					SELECT COUNT(*) FROM sqlite_master 
+					WHERE type='table' AND name='%s'
+				`, m.tableName)).Scan(&sqliteCount).Error
+				if err == nil && sqliteCount > 0 {
+					exists = true
+				}
+			}
+		}
+	}
+
+	// 如果查询失败，假设表不存在，尝试创建
 	if err != nil {
-		// 如果查询失败，可能是SQLite或其他数据库，尝试直接创建
 		exists = false
 	}
 
@@ -89,19 +169,57 @@ func (m *Migrator) initTable() error {
 		// 注意：这个检查可能在某些数据库中失败，但不影响功能
 		// 如果字段不存在，记录执行时间时会失败，但不影响迁移执行
 		var hasExecutionTime bool
-		checkSQL := fmt.Sprintf(`
-			SELECT COUNT(*) > 0 
-			FROM information_schema.columns 
-			WHERE table_schema = CURRENT_SCHEMA() 
-			AND table_name = '%s' 
-			AND column_name = 'execution_time'
-		`, m.tableName)
-		err = m.db.Raw(checkSQL).Scan(&hasExecutionTime).Error
-		if err == nil && !hasExecutionTime {
+		var columnCount int64
+		var checkErr error
+
+		switch m.dbType {
+		case "mysql":
+			// MySQL/MariaDB语法
+			checkErr = m.db.Raw(fmt.Sprintf(`
+				SELECT COUNT(*) 
+				FROM information_schema.columns 
+				WHERE table_schema = DATABASE() 
+				AND table_name = '%s' 
+				AND column_name = 'execution_time'
+			`, m.tableName)).Scan(&columnCount).Error
+			if checkErr == nil {
+				hasExecutionTime = columnCount > 0
+			}
+		case "postgres":
+			// PostgreSQL语法
+			checkErr = m.db.Raw(fmt.Sprintf(`
+				SELECT COUNT(*) 
+				FROM information_schema.columns 
+				WHERE table_schema = CURRENT_SCHEMA() 
+				AND table_name = '%s' 
+				AND column_name = 'execution_time'
+			`, m.tableName)).Scan(&columnCount).Error
+			if checkErr == nil {
+				hasExecutionTime = columnCount > 0
+			}
+		case "sqlite":
+			// SQLite不支持information_schema，跳过检查
+			hasExecutionTime = false
+		default:
+			// 兼容模式：尝试MySQL语法
+			checkErr = m.db.Raw(fmt.Sprintf(`
+				SELECT COUNT(*) 
+				FROM information_schema.columns 
+				WHERE table_schema = DATABASE() 
+				AND table_name = '%s' 
+				AND column_name = 'execution_time'
+			`, m.tableName)).Scan(&columnCount).Error
+			if checkErr == nil {
+				hasExecutionTime = columnCount > 0
+			}
+		}
+
+		if !hasExecutionTime {
 			// 尝试添加字段（如果失败不影响功能）
+			// 注意：SQLite的ALTER TABLE ADD COLUMN语法略有不同，但GORM会处理
 			_ = m.db.Exec(fmt.Sprintf(`
 				ALTER TABLE %s 
-				ADD COLUMN execution_time INT COMMENT '执行耗时(ms)'
+				ADD COLUMN execution_time INT
 			`, m.tableName))
 		}
 	}