1. mysql table

create table if not exists hwg_data_20151110(	id int primary key auto_increment,	dev_type smallint unsigned not null,	dev_id	 smallint unsigned not null,	data_time datetime not null,	data_time_ms smallint unsigned,	data_time_us smallint unsigned, 	yc_ac_ia smallint unsigned, 	yc_ac_ic smallint unsigned, 	yc_ac_in smallint unsigned, 	yx1 smallint unsigned, 	yx2 smallint unsigned, 	freq smallint unsigned,	tmp1 smallint unsigned, 	tmp2 smallint unsigned, 	tmp3 smallint unsigned);

drop procedure if exists proc_get_newest_yc;delimiter ///**@brief 禄帽脠隆脳卯脨脗脪拢虏芒脢媒戮脻***/create procedure ca9100db.proc_get_newest_yc(	OUT myval float)begin	declare mydate varchar(8);	declare date_str varchar(17);    declare sqlstr varchar(128);    	select date_format(current_date(), '%Y%m%d') into mydate;	select concat('hwg_data_',mydate) into date_str;    /*select date_str;*/    set @sqlstr = concat('', 'select yc_ac_ia from ');	set @sqlstr = concat(@sqlstr,date_str);    set @sqlstr = concat(@sqlstr,'');    select @sqlstr into sqlstr;    prepare sqlstr from @sqlstr;    execute sqlstr;end

void DataServices::data_dispatcher_init(){	string query_tbl_str;	string tbl_name;	string query_str;	MYSQL_ROW row;	MYSQL_RES *res;	unsigned char has_the_tbl = 0;	int ret;	string select_str;	if (!mysql_real_connect(&mysql, this->mysql_host.c_str(), 		this->mysql_user.c_str(), this->mysql_pwd.c_str(), this->mysql_dbname.c_str(), 		0, NULL, CLIENT_MULTI_STATEMENTS)) {		mysql_close(&mysql);		exit(1);		}	query_str = "call proc_get_newest_yc\(\@yc_ia\)";	ret = mysql_real_query(&mysql, query_str.c_str(), (unsigned long)query_str.length());	//ret = mysql_query(&(this->mysql), query_str);	res = mysql_store_result(&mysql);	while((row = mysql_fetch_row(res))) {		printf("[%s]\n", row[0]);	}}

这里需要特别注意一点：

在运行mysql_real_query/mysql_query执行存储过程的时候可能会返回1，其错误消息为 "Procedure myprocedure can't return a result set in the given context."

原因：与mysql_set_server_option() & mysql_real_connect()有关，mysql_real_connect函数的最后一个参数为client_flag，默认我们设置为0，但存储过程是在同一字符串中执行多个语句的，所以该参数需要修改默认值为CLIENT_MULTI_STATEMENTS。

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