C++ 如何重新使用MySQL++;查询对象以调用多个存储过程?
上面是程序。这里有几个错误:C++ 如何重新使用MySQL++;查询对象以调用多个存储过程?,c++,mysql++,C++,Mysql++,上面是程序。这里有几个错误: 您已经关闭了异常(conn(false)),但也没有检查错误代码的返回值。您的第二个execute()调用失败,但没有询问Query对象为什么,您正在盲目运行 不过,我认为允许MySQL++抛出异常(conn())并将整个过程包装在一个try块中比在所有MySQL++调用中添加错误检查更干净 您不需要使用多状态选项以当前显示的方式执行您的请求。这里有两个独立的语句,而不是一个复合语句。加上分号可能会让MySQL感到困惑,这就是第二次调用失败的原因 mysql命令行工
conn(false)
),但也没有检查错误代码的返回值。您的第二个execute()
调用失败,但没有询问Query
对象为什么,您正在盲目运行
不过,我认为允许MySQL++抛出异常(conn()
)并将整个过程包装在一个try
块中比在所有MySQL++调用中添加错误检查更干净多状态选项
以当前显示的方式执行您的请求。这里有两个独立的语句,而不是一个复合语句。加上分号可能会让MySQL感到困惑,这就是第二次调用失败的原因
mysql
命令行工具要求分号来终止SQL语句,但是当使用像mysql++这样的数据库API时,它们只需要分隔多个语句
您可以将两个CREATE
语句组合成一个字符串(和一个execute()
),也可以删除分号和多语句选项
reset()
调用就没有必要了。该方法仍然可用的唯一原因是,如果要重用已用于模板查询的查询
对象,则必须使用该方法;由于相当明显的原因,它们是唯一一种仍然不能自动重置的类型“它不工作”是什么意思?这意味着,代码只是创建了表“test1”,表“test2”丢失了,为什么?非常感谢您的提示!
#include <iostream>
#include <mysql++.h>
using namespace std;
int main() {
// Get database access parameters from command line
const char* db = "enet", *server = "192.168.1.108", *user = "root", *pass =
"123456";
// Connect to the sample database.
mysqlpp::Connection conn(false);
conn.set_option(new mysqlpp::MultiStatementsOption(true));
if (conn.connect(db, server, user, pass)) {
mysqlpp::Query query = conn.query();
query << "call CreateTable('test1', 'generic', 0, 1, 2, 3,4,5,6,7,8,9,10,NOW());";
query.execute();
query.reset();
query << "call CreateTable('test2', 'generic', 0, 1, 2, 3,4,5,6,7,8,9,10,NOW());";
query.execute();
query.reset();
return 0;
} else {
cerr << "DB connection failed: " << conn.error() << endl;
return 1;
}
return 0;
}
-- create table --
delimiter $$
drop procedure if exists CreateTable $$
create procedure CreateTable(
IN tableName VARCHAR(20),
IN dbName VARCHAR(20),
IN INT_RegDevID INTEGER,
IN Dec_Long DECIMAL(24,16),
IN Dec_Lat DECIMAL(24,16),
IN Dec_Height DECIMAL(10,6),
IN Dec_Direction DECIMAL(10,6),
IN AverageSpeed DECIMAL(10,6),
IN Dec_Base VARCHAR(10),
IN MCC INTEGER,
IN MNC INTEGER,
IN LAC INTEGER,
IN CI INTEGER,
IN Dec_LocaDate TIMESTAMP)
-- -------------------------------------------------------------------------------
-- -------------------------------------------------------------------------------
begin
-- the test variable
-- Warning: the encoding can result many problem!!!
declare varTableName VARCHAR(32) default NULL;
set @varTableName = NULL;
set @table_prefix = "posinfo_";
set @table_params = "(
`Int_LocaID` int(11) NOT NULL auto_increment,
`INT_RegDevID` int(11) NOT NULL default '0',
`Dec_Long` decimal(24,16) NOT NULL default '0.0000000000000000',
`Dec_Lat` decimal(24,16) NOT NULL default '0.0000000000000000',
`Dec_Height` decimal(10,6) NOT NULL default '0.000000',
`Dec_Direction` decimal(10,6) NOT NULL default '0.000000',
`Dec_ MaxSpeed` decimal(10,6) NOT NULL default '0.000000',
`Dec_ MinSpeed` decimal(10,6) NOT NULL default '0.000000',
`AverageSpeed` decimal(10,6) NOT NULL default '0.000000',
`Var_PosInfo` varchar(50) character set latin1 NOT NULL default '',
`Var_Remark` varchar(200) character set latin1 NOT NULL default '',
`Date_LocaDate` timestamp NOT NULL default CURRENT_TIMESTAMP,
`Dec_Base` varchar(10) character set latin1 NOT NULL,
`MCC` int(11) NOT NULL COMMENT '',
`MNC` int(11) NOT NULL COMMENT '',
`LAC` int(11) NOT NULL COMMENT '',
`CI` int(11) NOT NULL COMMENT '',
PRIMARY KEY (`Int_LocaID`)
) ENGINE=MyISAM AUTO_INCREMENT=0 DEFAULT CHARSET=gbk;";
set @varCreate = CONCAT("create table ", dbName,".",@table_prefix, tableName, @table_params);
-- the insert operation
set @insertOperation = CONCAT("insert into ", dbName,".",@table_prefix, tableName,
"(INT_RegDevID,Dec_Long,Dec_Lat,Dec_Height,Dec_Direction,AverageSpeed,
Dec_Base,MCC,MNC,LAC,CI,Date_LocaDate) values(",INT_RegDevID,",",Dec_Long,
",",Dec_Lat,",",Dec_Height,",",Dec_Direction,",",AverageSpeed,",",Dec_Base,
",",MCC,",",MNC,",",LAC,",",CI,",NOW())");
-- find the target table
-- Look care about the "' '" !
set @getTargetTable = CONCAT("select TABLE_NAME into @varTableName from INFORMATION_SCHEMA.TABLES where TABLE_SCHEMA='",
dbName, "' and TABLE_NAME='", @table_prefix, tableName,"'");
-- -------------------------------------------------------------------------------
-- -------------------------------------------------------------------------------
PREPARE getTargetTable from @getTargetTable;
execute getTargetTable;
select @varTableName;
set varTableName = @varTableName;
if varTableName is NULL then
-- create new table
PREPARE newTable
from @varCreate;
execute newTable;
-- do insert operation
PREPARE insertOperation
from @insertOperation;
execute insertOperation;
else
-- do insert operation
PREPARE insertOperation
from @insertOperation;
execute insertOperation;
end if;
end $$
delimiter ;