classlib.lua

--classlib.lua
local loadstring = loadstring
-------OOP
local getmetatable,setmetatable,setfenv = getmetatable,setmetatable,setfenv
local tonumber,tostring = tonumber,tostring
local _call = call
local function call(...)
	local _source = source
	local retValue = {_call(...)}
	source = _source
	return unpack(retValue)
end
-------Utils
local strToIntCache = {
	["vector2"]=2,
	["vector3"]=3,
	["vector4"]=4,
}
oopUtil = {
	classReg = {},
	classMetaReg = {},
	instanceReg = setmetatable({},{__mode="kv"}),
	eventHandler = {},
	transfromEventName = function(eventName,isReverse)
		return isReverse and (eventName:sub(3,3):lower()..eventName:sub(4)) or ("on"..eventName:sub(1,1):upper()..eventName:sub(2))
	end,
	getVectorType = function(vec)
		if type(vec) == "userdata" then
			local typeName = getUserdataType(vec)
			if typeName == "vector" then
				return strToIntCache[typeName]
			end
		end
		return false
	end,
	deepCopyWithMeta = function(obj)
		local function Func(obj)
			if type(obj) ~= "table" then return obj end
			local NewTable = {}
			for k,v in pairs(obj) do
				NewTable[Func(k)] = Func(v)
			end
			return setmetatable(NewTable,getmetatable(obj))
		end
		return Func(obj)
	end,
	splitKeyValue = function(theTable)
		local keyTable = {}
		local valueTable = {}
		for key,value in pairs(theTable) do
			keyTable[#keyTable+1] = key
			valueTable[#valueTable+1] = value
		end
		return keyTable,valueTable
	end;
	deepCopy = function(obj)
		local function Func(obj)
			if type(obj) ~= "table" then return obj end
			local NewTable = {}
			for k,v in pairs(obj) do
				NewTable[Func(k)] = Func(v)
			end
			return NewTable
		end
		return Func(obj)
	end,
	shallowCopy = function(obj)
		local InTable = {}
		for k,v in pairs(obj) do
			InTable[k] = v
		end
		return InTable
	end,
	assimilate = function(t1,t2,except)
		if not t1 or not t2 then return end
		local exceptTable = {}
		if type(except) == "table" then
			for i=1,#except do
				exceptTable[ except[i] ] = true
			end
		end
		for k,v in pairs(t2) do
			if not exceptTable[k] then
				t1[k] = v
			end
		end
	end,
	spreadFunctionsForClass = function(class,classTemplate)
		oopUtil.assimilate(class,classTemplate,{"expose","constructor"})
		oopUtil.assimilate(class,classTemplate)
	end,
	configToSql = function(self,dbType)
		local strTable = {}
		local specialKeys = {}
		local theDataType
		for columnName,dType in pairs(self) do
			if type(dType) == "string" then
				local extraTags = ""
				if string.find(dType,";") then
					local items = split(dType,";")
					theDataType = sqlDataType[items[1]] or items[1]
					for i=2,#items do
						local tag = items[i]:lower():gsub(" ","")
						if tag:sub(1,7) == "primary" then
							extraTags = extraTags.." Primary Key "
						elseif tag:sub(1,6) == "unique" then
							extraTags = extraTags.." Unique "
						elseif tag:sub(1,7) == "foreign" then
							specialKeys[#specialKeys+1] = "Foreign Key (`"..columnName.."`) References "..items[i]:sub(8)
						elseif tag == "notnull" then
							extraTags = extraTags.." Not Null "
						elseif tag == "defaultnull" then
							extraTags = extraTags.." Default Null "
						elseif tag == "autoincrement" or tag == "auto_increment" then
							extraTags = extraTags.." Auto_Increment "
						end
					end
				else
					theDataType = sqlDataType[dType] or dType
				end
				strTable[#strTable+1] = "`"..columnName.."` "..theDataType.." "..extraTags
			end
		end
		for i=1,#specialKeys do
			strTable[#strTable+1] = specialKeys[i]
		end
		return table.concat(strTable,",")
	end,
}

function class(name) return function(classTable)
	oopUtil.classReg[name] = classTable	--register class with class name
	oopUtil.classMetaReg[name] = {__index = {}}	--register class metatable with class name
	local meta = {
		__call = function(classTemplate,...)
			local newInstance = {}
			setmetatable(newInstance,oopUtil.classMetaReg[name])
			if classTemplate.constructor then
				classTemplate.constructor(newInstance,...)
			else
				local copyData = ...
				if type(copyData) ~= "table" then return newInstance end
				for k,v in pairs(copyData) do
					newInstance[k] = v
				end
			end
			return newInstance
		end,
	}
	if classTable.extend then
		if type(classTable.extend) ~= "table" then
			local extendClass = oopUtil.classReg[classTable.extend]
			for extKey,extFunction in pairs(extendClass) do
				if classTable[extKey] == nil then classTable[extKey] = extFunction end	--Don't overwrite child's function when copying parent's functions
			end
		else
			for key,extend in ipairs(classTable.extend) do
				local extendClass = oopUtil.classReg[extend]
				for extKey,extFunction in pairs(extendClass) do
					if classTable[extKey] == nil then classTable[extKey] = extFunction end	--Don't overwrite child's function when copying parent's functions
				end
			end
		end
	end
	if classTable.inject then
		for theType,space in pairs(classTable.inject) do
			local injectedData = oopUtil.classReg[theType]
			if not injectedData then injectedData = {} end
			for name,fnc in pairs(space or {}) do
				injectedData[name] = fnc
			end
			for name,fnc in pairs(space or {}) do
				injectedData[name] = fnc
			end
		end
	end
	meta.__index = {class=name}
	setmetatable(classTable,meta)
	oopUtil.spreadFunctionsForClass(oopUtil.classMetaReg[name].__index,classTable)
	oopUtil.classMetaReg[name].__index.class = name
	oopUtil.classMetaReg[name].__index.instance = true
	if not classTable.expose then
		_G[name] = classTable
	elseif oopUtil.classMetaReg[classTable.expose] then
		oopUtil.classMetaReg[classTable.expose].__index[name] = function(self,...) return classTable(...) end
	end
end
end
oopUtil.class = class

--Types:
sqlDataType = {
	integer = "int",
	int = "int",
	int8 = "tinyint",
	int16 = "smallint",
	int24 = "mediumint",
	int32 = "int",
	int64 = "bigint",
	uint = "int unsigned",
	uint8 = "tinyint unsigned",
	uint16 = "smallint unsigned",
	uint24 = "mediumint unsigned",
	uint32 = "int unsigned",
	uint64 = "bigint unsigned",
	-- 字符串类型
	char = "char",
	varchar = "varchar",
	text = "text",
	mediumtext = "mediumtext",
	longtext = "longtext",
	-- 浮点数类型
	float = "float",
	double = "double",
	decimal = "decimal",
	-- 日期时间类型
	date = "date",
	time = "time",
	datetime = "datetime",
	timestamp = "timestamp",
	-- 布尔类型
	boolean = "boolean",
	bool = "bool",
	-- 二进制类型
	blob = "blob",
	mediumblob = "mediumblob",
	longblob = "longblob",
}

class "MORM" {
	Open = function(self,...)
		return oopUtil.classReg.DataBase(...)
	end;
}

class "DataBase" {
	expose = "MORM",
	constructor = function(self,dbType,...)
		-- 检查数据库类型参数
		if not dbType then
			outputDebugString("@DataBase.constructor, database type is required", 3)
			return nil
		end
		
		-- 尝试连接数据库
		self.db = dbConnect(dbType,...)
		if not self.db then
			outputDebugString("@DataBase.constructor, failed to connect to database", 3)
			return nil
		end
		
		self.dbString = {}
		self.dbType = dbType
		self.dbPendingFill = nil
	end;
	--[[
		AutoMigrate: 自动迁移数据库结构
		参数:
			tableName: 表名
			classTemplate: 类模板，包含列定义
		功能:
			检查表是否存在，如果不存在则创建新表
			如果表存在，则检查是否需要添加新列
	]]
	AutoMigrate = function(self,...)
		if select("#",...) == 2 then
			local first,second = ...
			--"tableName", classTemplate
			if type(first) == "string" then
				local tableName, classTemplate = first, second
				-- 检查表是否存在
				local checkQuery = dbPrepareString(self.db, "SELECT name FROM sqlite_master WHERE type='table' AND name='??'", tableName)
				local handle = dbQuery(self.db, checkQuery)
				local result = dbPoll(handle, -1)
				
				if #result == 0 then
					-- 表不存在，创建新表
					self.dbString[#self.dbString+1] = dbPrepareString(self.db,"Create Table If Not Exists `??` (??)", tableName, oopUtil.configToSql(classTemplate, self.dbType))
				else
					-- 表存在，检查是否需要更新结构
					-- 这里可以添加更复杂的表结构比较逻辑
					-- 简化实现：总是尝试添加新列
					for columnName, dataType in pairs(classTemplate) do
						if type(dataType) == "string" and columnName ~= "class" and columnName ~= "instance" then
							-- 检查列是否存在
							local columnCheckQuery = dbPrepareString(self.db, "PRAGMA table_info(`??`)", tableName)
							local columnHandle = dbQuery(self.db, columnCheckQuery)
							local columns = dbPoll(columnHandle, -1)
							local columnExists = false
							for _, columnInfo in ipairs(columns) do
								if columnInfo.name == columnName then
									columnExists = true
									break
								end
							end
							
							if not columnExists then
								-- 添加新列
								local sqlDataType = sqlDataType[dataType] or dataType
								local addColumnQuery = dbPrepareString(self.db, "ALTER TABLE `??` ADD COLUMN `??` ??", tableName, columnName, sqlDataType)
								self.dbString[#self.dbString+1] = addColumnQuery
							end
						end
					end
				end
			end
		end
		return self
	end;
	--[[
		Create: 创建表或插入数据
		参数:
			tableName: 表名（可选）
			template: 类模板或实例
		功能:
			如果template是实例，则插入数据到表中
			如果template是类模板，则创建新表
	]]
	Create = function(self,...)
		local tableName,template
		if select("#",...) == 1 then
			template = ...
			if not(type(template) == "table" and template.class) then outputDebugString("@Create at argument 1, expect a Class/Instance got "..type(template),3) return false end
			if not self.dbString.table then --if table name is not specified
				if not(type(template.class) == "string") then outputDebugString("@Create, table name is not specified",3) return false end
			end
			tableName = self.dbString.table or template.class
		else
			tableName,template = ...
			if not(type(tableName) == "string") then outputDebugString("@Create at argument 1, expect a string got "..type(tableName),3) end
			if not(type(template) == "table") then outputDebugString("@Create at argument 2, expect a Class/table got "..type(template),3) end
			tableName = self.dbString.table or tableName
		end
		if template.instance then	--If is instance, just insert
			self.dbString[#self.dbString+1] = dbPrepareString(self.db,"Insert Into `??` ",tableName)
			local ks,vs = oopUtil.splitKeyValue(template)
			local keys,values = {},{}
			for i=1,#ks do
				keys[#keys+1] = dbPrepareString(self.db,"`??`",ks[i])
				values[#values+1] = dbPrepareString(self.db,"?",vs[i])
			end
			self.dbString[#self.dbString+1] = "("..table.concat(keys,",")..") Values ("..table.concat(values,",")..")"
		else
			self.dbString[#self.dbString+1] = dbPrepareString(self.db,"Create Table If Not Exists `??` (??)",self.dbString.table or template.class,oopUtil.configToSql(template,self.dbType))
		end
		return self
	end;
	--[[
		Select: 添加SELECT子句
		参数:
			selectColumn: 要选择的列（可选，默认为"*"）
		功能:
			为查询添加SELECT子句
			如果已指定表名，则同时添加FROM子句
		返回值:
			返回self，支持链式调用
	]]
	Select = function(self,selectColumn)
		self.dbString[#self.dbString+1] = dbPrepareString(self.db,"Select ?? ",selectColumn or "*")
		if self.dbString.table then
			self.dbString[#self.dbString+1] = dbPrepareString(self.db,"From `??` ",self.dbString.table)
		end
		return self
	end;
	--[[
		From: 添加FROM子句
		参数:
			fromTable: 表名（可选，如果已通过Table函数指定）
		功能:
			为查询添加FROM子句
		返回值:
			返回self，支持链式调用
	]]
	From = function(self,fromTable)
		if not fromTable then
			if not self.dbString.table then outputDebugString("@From, table name is not specified",3) return false end
			self.dbString[#self.dbString+1] = dbPrepareString(self.db,"From `??` ",self.dbString.table)
		else
			if self.dbString.table then outputDebugString("@From, table name is already specified",3) return false end
			self.dbString[#self.dbString+1] = dbPrepareString(self.db,"From `??` ",fromTable)
		end
		return self
	end;
	--[[
		Where: 添加WHERE子句
		参数:
			columnName: 列名
			value: 值
		功能:
			为查询添加WHERE子句
		返回值:
			返回self，支持链式调用
	]]
	Where = function(self,columnName,value)
		self.dbString[#self.dbString+1] = dbPrepareString(self.db,"Where `??` = ? ",columnName,value)
		return self
	end;
	--[[
		OrderBy: 添加ORDER BY子句
		参数:
			columnName: 列名
			order: 排序方式（ASC/DESC，默认ASC）
		功能:
			为查询添加ORDER BY子句
		返回值:
			返回self，支持链式调用
	]]
	OrderBy = function(self, columnName, order)
		if not columnName then
			outputDebugString("@OrderBy, column name is required", 3)
			return false
		end
		
		local orderBy = order and order:upper() or "ASC"
		if orderBy ~= "ASC" and orderBy ~= "DESC" then
			orderBy = "ASC"
		end
		
		self.dbString[#self.dbString+1] = dbPrepareString(self.db, "ORDER BY `??` ??", columnName, orderBy)
		return self
	end;
	--[[
		Limit: 添加LIMIT子句
		参数:
			limit: 限制的行数
			offset: 偏移量（可选）
		功能:
			为查询添加LIMIT子句
		返回值:
			返回self，支持链式调用
	]]
	Limit = function(self, limit, offset)
		if not limit then
			outputDebugString("@Limit, limit is required", 3)
			return false
		end
		
		if offset then
			self.dbString[#self.dbString+1] = dbPrepareString(self.db, "LIMIT ? OFFSET ?", limit, offset)
		else
			self.dbString[#self.dbString+1] = dbPrepareString(self.db, "LIMIT ?", limit)
		end
		return self
	end;
	--[[
		Find: 查找数据
		参数:
			instance: 实例或实例列表
		功能:
			根据实例的属性值构建WHERE条件进行查询
			如果instance是单个实例，则构建AND条件
			如果instance是实例列表，则构建OR条件
			查询结果将填充到实例中
		返回值:
			返回self，支持链式调用
	]]
	Find = function(self,...)
		local argCount = select("#",...)
		if argCount == 1 then
			local instance = ...
			if not(type(instance) == "table") then outputDebugString("@Find at argument 1, expect a table/Instance got "..type(instance),3) return false end
			if instance.instance == true then	--If is instance
				if not self.dbString.table then self.dbString.table = instance.class end
				self:Select()
				local where = {}
				for key,value in pairs(instance) do
					where[#where+1] = dbPrepareString(self.db," `??` = ? ",key,value)
				end
				self.dbString[#self.dbString+1] = "Where"..table.concat(where,"and")
				self.dbPendingFill = {instance}
			else	--Otherwise, Instance List
				if not self.dbString.table then self.dbString.table = instance[1].class end
				local conditions = {}
				for i=1,#instance do
					local where = {}
					for key,value in pairs(instance[i]) do
						where[#where+1] = dbPrepareString(self.db," `??` = ? ",key,value)
					end
					conditions[#conditions+1] = " ("..table.concat(where,"and")..") "
				end
				self:Select()
				self.dbString[#self.dbString+1] = "Where"..table.concat(conditions,"or")
				self.dbPendingFill = instance
			end
		end
		return self
	end;
	--[[
		Update: 更新数据
		参数:
			可以有多种参数组合：
			1. template: 实例或类模板
			2. key, value: 列名和值
			3. tableNameOrTemplate, template: 表名或模板，以及模板
			4. tableNameOrTemplate, key, value: 表名或模板，列名和值
		功能:
			构建UPDATE语句更新数据
		返回值:
			返回self，支持链式调用
	]]
	Update = function(self,...)
		local argCount = select("#",...)
		if argCount == 1 then
			local template = ...
			if not(type(template) == "table") then outputDebugString("@Update at argument 1, expect a Class/Instance got "..type(template),3) return false end
			if not self.dbString.table then
				if not(type(template.class) == "string") then outputDebugString("@Update, table name is not specified",3) return false end
				self.dbString.table = template.class
			end
			self.dbString[#self.dbString+1] = dbPrepareString(self.db,"Update `??` SET ",self.dbString.table)
			local kvPair = {}
			for key,value in pairs(template) do
				local vType = type(value)
				if vType ~= "userdata" and vType ~= "function" then
					kvPair[#kvPair+1] = dbPrepareString(self.db," `??` = ? ",key,value)
				end
			end
			self.dbString[#self.dbString+1] = table.concat(kvPair,",")
		elseif argCount == 2 then
			local key,value = ...
			if type(value) == "table" then
				local tableNameOrTemplate,template = ...
				if not (type(tableNameOrTemplate) == "string" or (type(tableNameOrTemplate) == "table" and tableNameOrTemplate.class)) then outputDebugString("@Update at argument 1, expect a Class/string got "..type(tableNameOrTemplate),3) end
				if not(type(template) == "table") then outputDebugString("@Update at argument 2, expect a table/Instance got "..type(template),3) return false end
				if not self.dbString.table then
					if type(tableNameOrTemplate) == "string" then
						self.dbString.table = tableNameOrTemplate
					else
						self.dbString.table = tableNameOrTemplate.class
					end
				end	--Skip if table is already specified
				self.dbString[#self.dbString+1] = dbPrepareString(self.db,"Update `??` SET ",self.dbString.table)
				local kvPair = {}
				for key,value in pairs(template) do
					local vType = type(value)
					if vType ~= "userdata" and vType ~= "function" then
						kvPair[#kvPair+1] = dbPrepareString(self.db," `??` = ? ",key,value)
					end
				end
				self.dbString[#self.dbString+1] = table.concat(kvPair,",")
			else
				if not (type(key) == "string") then outputDebugString("@Update at argument 1, expected a string got "..type(key),3) return false end
				if not self.dbString.table then outputDebugString("@Update, table name is not specified",3) return false end
				self.dbString[#self.dbString+1] = dbPrepareString(self.db,"Update `??` SET `??` = ? ",self.dbString.table,key,value)
			end
		elseif argCount == 3 then
			local tableNameOrTemplate,key,value = ...
			if not (type(tableNameOrTemplate) == "string" or (type(tableNameOrTemplate) == "table" and tableNameOrTemplate.class)) then outputDebugString("@Update at argument 1, expect a Class/string got "..type(tableNameOrTemplate),3) end
			if not (type(key) == "string") then outputDebugString("@Update at argument 2, expected a string got "..type(key),3) return false end
			if not self.dbString.table then
				if type(tableNameOrTemplate) == "string" then
					self.dbString.table = tableNameOrTemplate
				else
					self.dbString.table = tableNameOrTemplate.class
				end
			end	--Skip if table is already specified
			if not self.dbString.table then outputDebugString("@Update, table name is not specified",3) return false end
			self.dbString[#self.dbString+1] = dbPrepareString(self.db,"Update`??` SET `??` = ? ",self.dbString.table,key,value)
		end
		return self
	end;
	--[[
		Delete: 删除表
		参数:
			tableName: 表名
		功能:
			删除指定的表
		返回值:
			返回self，支持链式调用
	]]
	Delete = function(self,tableName)
		self.dbString[#self.dbString+1] = dbPrepareString(self.db,"Drop Table If Exists ?",tableName)
		return self
	end;
	--[[
		Query: 执行数据库查询
		参数:
			timedout: 超时时间（可选，默认-1）
			callback: 回调函数（可选，异步执行）
		功能:
			执行构建好的SQL查询语句
			支持同步和异步执行
			如果设置了dbPendingFill，则将查询结果填充到指定的实例中
		返回值:
			异步执行时返回true/false
			同步执行时返回查询结果或nil
	]]
	Query = function(self,timedout,callback)
		-- 检查数据库连接
		if not self.db then
			outputDebugString("@Query, no database connection", 3)
			if callback then
				callback(self, nil)
				return false
			else
				return nil
			end
		end
		
		-- 检查是否有查询语句
		if #self.dbString == 0 then
			outputDebugString("@Query, no query statement", 3)
			if callback then
				callback(self, nil)
				return false
			else
				return nil
			end
		end
		
		local _self = self
		local pendingFill = self.dbPendingFill
		self.dbPendingFill = nil
		local queryString = table.concat(self.dbString)
		
		if callback then
			-- 异步查询
			local handle = dbQuery(function(handle)
				self = _self
				local pollData, err = dbPoll(handle,timedout or -1)
				if err then
					outputDebugString("@Query, database error: " .. tostring(err), 3)
					callback(self, nil)
					return
				end
				
				if pollData and pendingFill then	--Pending To Fill
					local successCount = 0
					for i=1,#pendingFill do			--Loop Pending To Fill List
						local p = 1
						while(pollData[p]) do		--Loop Retrieved Data List
							local isCopyData = true
							for key,value in pairs(pendingFill[i]) do		--Compare Data
								if pollData[p][key] ~= value then isCopyData = false break end	--Continue
							end
							if isCopyData then
								for key,value in pairs(pollData[p]) do			--Copy Data
									pendingFill[i][key] = value
								end
								successCount = successCount+1
								table.remove(pollData,p)						--Remove copied data
								p = #pollData
							end
							p = p+1
						end
					end
					callback(self,successCount)
				else
					callback(self,pollData)
				end
			end,self.db,queryString)
			
			if not handle then
				outputDebugString("@Query, failed to execute query", 3)
				callback(self, nil)
				return false
			end
			
			print(queryString)
			self.dbString = {}
			return true
		else
			-- 同步查询
			local handle = dbQuery(self.db,queryString)
			if not handle then
				outputDebugString("@Query, failed to execute query", 3)
				self.dbString = {}
				return nil
			end
			
			print(queryString)
			self.dbString = {}
			local pollData, err = dbPoll(handle,timedout or -1)
			if err then
				outputDebugString("@Query, database error: " .. tostring(err), 3)
				return nil
			end
			
			if pollData and pendingFill then	--Pending To Fill
				local successCount = 0
				for i=1,#pendingFill do			--Loop Pending To Fill List
					local p = 1
					while(pollData[p]) do		--Loop Retrieved Data List
						local isCopyData = true
						for key,value in pairs(pendingFill[i]) do		--Compare Data
							if pollData[p][key] ~= value then isCopyData = false break end	--Continue
						end
						if isCopyData then
							for key,value in pairs(pollData[p]) do			--Copy Data
								pendingFill[i][key] = value
							end
							successCount = successCount+1
							table.remove(pollData,p)						--Remove copied data
							p = #pollData
						end
						p = p+1
					end
				end
				return successCount
			end
			return pollData
		end
	end;
	--[[
		Raw: 添加原始SQL语句
		参数:
			raw: 原始SQL语句
			...: 参数
		功能:
			添加原始SQL语句到查询字符串中
		返回值:
			返回self，支持链式调用
	]]
	Raw = function(self,raw,...)
		if not(type(raw) == "string") then return outputDebugString("@Raw at argument 1, expect a string got "..type(raw),3) end
		self.dbString[#self.dbString+1] = dbPrepareString(self.db,raw,...)
		return self
	end;
	--[[
		Table: 指定表名
		参数:
			tableNameOrTemplate: 表名或类模板
		功能:
			指定要操作的表名
			这个表名具有最高优先级
		返回值:
			返回self，支持链式调用
	]]
	Table = function(self,tableNameOrTemplate)
		--Use this table if specified by :Table("tableName"), and this has the top priority.
		if not (type(tableNameOrTemplate) == "string" or (type(tableNameOrTemplate) == "table" and tableNameOrTemplate.class)) then outputDebugString("@Table at argument 1, expect a Class/string got "..type(tableNameOrTemplate),3) end
		self.dbString.table = (type(tableNameOrTemplate) == "string") and tableNameOrTemplate or tableNameOrTemplate.class
		return self
	end;
	--[[
		Alert: 修改列定义
		参数:
			tableName: 表名
			columnName: 列名
			newDefinition: 新的列定义
		功能:
			修改指定列的定义
		返回值:
			返回self，支持链式调用
	]]
	Alert = function(self, tableName, columnName, newDefinition)
		if not tableName or not columnName or not newDefinition then
			outputDebugString("@Alert, missing required parameters", 3)
			return false
		end
		
		-- 构造ALTER TABLE语句
		local sql = "ALTER TABLE `" .. tableName .. "` ALTER COLUMN `" .. columnName .. "` " .. newDefinition
		self.dbString[#self.dbString+1] = dbPrepareString(self.db, sql)
		return self
	end;
	--[[
		BeginTransaction: 开始事务
		功能:
			开始一个新的数据库事务
		返回值:
			返回self，支持链式调用
	]]
	BeginTransaction = function(self)
		if not self.db then
			outputDebugString("@BeginTransaction, no database connection", 3)
			return false
		end
		
		-- 开始事务
		local success = dbExec(self.db, "BEGIN")
		if not success then
			outputDebugString("@BeginTransaction, failed to begin transaction", 3)
			return false
		end
		
		return self
	end;
	--[[
		Commit: 提交事务
		功能:
			提交当前事务的所有更改
		返回值:
			返回self，支持链式调用
	]]
	Commit = function(self)
		if not self.db then
			outputDebugString("@Commit, no database connection", 3)
			return false
		end
		
		-- 提交事务
		local success = dbExec(self.db, "COMMIT")
		if not success then
			outputDebugString("@Commit, failed to commit transaction", 3)
			return false
		end
		
		return self
	end;
	--[[
		Rollback: 回滚事务
		功能:
			回滚当前事务的所有更改
		返回值:
			返回self，支持链式调用
	]]
	Rollback = function(self)
		if not self.db then
			outputDebugString("@Rollback, no database connection", 3)
			return false
		end
		
		-- 回滚事务
		local success = dbExec(self.db, "ROLLBACK")
		if not success then
			outputDebugString("@Rollback, failed to rollback transaction", 3)
			return false
		end
		
		return self
	end;
	--[[
		Drop: 删除表或列
		参数:
			tableName: 表名
			columnName: 列名（可选）
		功能:
			如果指定了列名，则删除指定的列
			否则删除整个表
		返回值:
			返回self，支持链式调用
	]]
	Drop = function(self, tableName, columnName)
		if not tableName then
			outputDebugString("@Drop, table name is required", 3)
			return false
		end
		
		if columnName then
			-- 删除列
			local sql = "ALTER TABLE `" .. tableName .. "` DROP COLUMN `" .. columnName .. "`"
			self.dbString[#self.dbString+1] = dbPrepareString(self.db, sql)
		else
			-- 删除表
			self.dbString[#self.dbString+1] = dbPrepareString(self.db, "DROP TABLE IF EXISTS `??`", tableName)
		end
		return self
	end;
	--[[
		Change: 修改列名和定义
		参数:
			tableName: 表名
			columnName: 列名
			newDefinition: 新的列定义
		功能:
			修改指定列的名称和定义
		返回值:
			返回self，支持链式调用
	]]
	Change = function(self, tableName, columnName, newDefinition)
		if not tableName or not columnName or not newDefinition then
			outputDebugString("@Change, missing required parameters", 3)
			return false
		end
		
		-- 构造CHANGE COLUMN语句
		local sql = "ALTER TABLE `" .. tableName .. "` CHANGE COLUMN `" .. columnName .. "` `" .. columnName .. "` " .. newDefinition
		self.dbString[#self.dbString+1] = dbPrepareString(self.db, sql)
		return self
	end;
	--[[
		Add: 添加列
		参数:
			tableName: 表名
			columnName: 列名
			columnDefinition: 列定义
		功能:
			向指定表添加新列
		返回值:
			返回self，支持链式调用
	]]
	Add = function(self, tableName, columnName, columnDefinition)
		if not tableName or not columnName or not columnDefinition then
			outputDebugString("@Add, missing required parameters", 3)
			return false
		end
		
		-- 构造ADD COLUMN语句
		local sql = "ALTER TABLE `" .. tableName .. "` ADD COLUMN `" .. columnName .. "` " .. columnDefinition
		self.dbString[#self.dbString+1] = dbPrepareString(self.db, sql)
		return self
	end;
	--[[
		Modify: 修改列定义
		参数:
			tableName: 表名
			columnName: 列名
			newDefinition: 新的列定义
		功能:
			修改指定列的定义
		返回值:
			返回self，支持链式调用
	]]
	Modify = function(self, tableName, columnName, newDefinition)
		if not tableName or not columnName or not newDefinition then
			outputDebugString("@Modify, missing required parameters", 3)
			return false
		end
		
		-- 构造MODIFY COLUMN语句
		local sql = "ALTER TABLE `" .. tableName .. "` MODIFY COLUMN `" .. columnName .. "` " .. newDefinition
		self.dbString[#self.dbString+1] = dbPrepareString(self.db, sql)
		return self
	end;
}
morm = MORM()