openresty 中lua 操作mysql，

lua在mysql的中操作使用

lua-resty-mysql是为基于cosocket API的ngx_lua提供的Lua Mysql客户端，通过它可以完成Mysql的操作。默认安装OpenResty时已经自带了该模块，使用文档可参考https://github.com/openresty/lua-resty-mysql。

#lua操作mysql
	location = /testMysql{
		#lua_code_cache off; 		
		content_by_lua_block{
			local function close_db(db)
				if not db then
					return
				end
				db:close()
			end	
			
			local mysql = require("resty.mysql")  
			--创建实例  
			local db, err = mysql:new()  
			if not db then  
    				ngx.say("new mysql error : ", err)  
    				return  
			end  
			--设置超时时间(毫秒)  
			db:set_timeout(1000)  
  
			local props = {  
    				host = "10.23.148.251",  
    				port = 3306,
    				database = "db1", 
    				user = "root",
  				password = "123456"  
			}  
  
			local res, err, errno, sqlstate = db:connect(props)  
  
			if not res then  
   				ngx.say("connect to mysql error : ", err, " , errno : ", errno, " , sqlstate : ", sqlstate)  
   				return close_db(db)  
			end 
				
			--建表
			--local create_sql = "create table test_lua(id int primary key auto_increment,ch varchar(20))"
			--res,err,errno,sqlstate = db:query(create_sql)
			--if not res then
			--	ngx.say("create table error:",err,",errno:",errno,",sqlstate:",sqlstate)
			--	return close_db(db)
			--end
			--新增sql
			local insert_sql = "insert into test_lua(ch) values('hello 崔春驰')"
			res,err,errno,sqlstate = db:query(insert_sql)
			if not res then	
				ngx.say("insert rows error:",err,",errno:",errno,",sqlstate:",sqlstate)
				return close_db(db)
			end
			ngx.say("insert rows:",res.affected_row,",id:",res.insert_id,",res:",type(res))
			
			--更新
			local update_sql = " update test_lua set ch = 'hello2' where id = 1"
						
			res,err,errno,sqlstate = db:query(update_sql)
			if not res then	
				ngx.say("update rows error:",err,",errno:",errno,",sqlstate:",sqlstate)
				return close_db(db)
			end
			ngx.say("update rows:",res.affected_row,",res:",type(res))
				
			--查询
			local select_sql = " select id,ch from test_lua"
									
			res,err,errno,sqlstate = db:query(select_sql)
			if not res then	
				ngx.say("select rows error:",err,",errno:",errno,",sqlstate:",sqlstate)
				return close_db(db)
			end
			for i,row in ipairs(res) do
				for name,id in pairs(row) do
					ngx.say("select rows :",i,":",name,"=",id)
				end
			end
			ngx.say("select rows:",res.affected_row,",res:",type(res))

			--防止sql注入
			local ch_param = ngx.req.get_uri_args()["ch"]
			ngx.say("ch_param:",ch_param)
			if not ch_param then
				ch_param = ''
			end
			
			--使用ngx.quote_sql_str防止sql注入
			local query_sql = " select id,ch from test_lua where ch  =" .. ngx.quote_sql_str(ch_param)
			res,err,errno,sqlstate = db:query(query_sql)
			if not res then	
				ngx.say("select rows error:",err,",errno:",errno,",sqlstate:",sqlstate)
				return close_db(db)
			end
			
			for i,row in ipairs(res) do
				for name,id in pairs(row) do
					ngx.say("select rows :",i,":",name,"=",id)
				end
			end
				
			--删除
			local delete_sql = "delete from test_lua where id in (2,3,4)"
			res,err,errno,sqlstate = db:query(delete_sql)
			if not res then	
				ngx.say("delete rows error:",err,",errno:",errno,",sqlstate:",sqlstate)
				return close_db(db)
			end
			ngx.say("delete rows:",res.affected_rows,"")
						

测试结果：

客户端目前还没有提供预编译SQL支持（即占位符替换位置变量），这样在入参时记得使用ngx.quote_sql_str进行字符串转义，防止sql注入；

连接池和之前Redis客户端完全一样就不介绍了。

其中用到的lua-resty-mysql的一些API方法：

 db, err = mysql:new() 创建一个mysql数据库连接对象
 ok, err = db:connect(options) 尝试远程连接mysql
     host mysql的主机名
     port 端口
     database 数据库名
     user 用户名
     password 密码
     charset 编码
 db:set_timeout(time) 设置数据库连接超时时间
 ok, err = db:set_keepalive(max_idle_timeout, pool_size) 设置连接池
 ok, err = db:close() 关闭数据库
 bytes, err = db:send_query(query) 发送查询

对于Mysql客户端的介绍基本够用了，更多请参考https://github.com/openresty/lua-resty-mysql。