0 
#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;
}

我想使用mysql ++查询多次执行过程“CreateTable”，最后我重置了查询，但无论如何，只有第一个查询有效，最后一个无效，我的问题是：如何进行所有查询工作？

-- 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 ;

以上，是程序。

4

1 回答 1

1

这里有几个错误：

  1. 您已关闭异常 ( conn(false))，但您也没有检查错误代码的返回值。你的第二个execute()电话失败了，但没有问Query对象为什么，你就瞎了。

    conn()不过，与其向所有 MySQL++ 调用添加错误检查，我认为允许 MySQL++ 抛出异常try（

  2. 您不需要MultiStatementsOption按照您当前显示的方式执行您所要求的操作。您在这里有两个单独的语句，而不是一个复合语句。与分号结合使用可能会使 MySQL 感到困惑，这就是第二次调用失败的原因。

    命令行mysql工具需要分号来终止 SQL 语句，但是当使用 MySQL++ 之类的数据库 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MultiStatementsOption.

  3. reset()自 MySQL++ 2.x 以来，查询之间的调用就不再需要了。该方法仍然可用的唯一原因是，如果您想重用Query已用于模板查询的对象，则它是必要的；由于相当明显的原因，它们是唯一仍然不会自动重置的类型。

于 2011-03-08T18:12:17.570 回答