我按照mysql参考手册上的例子做的东东..为什么老是出现数据截断问题..

而手册上说一般不会出现的.--中的内容来自手册

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MYSQL_DATA_TRUNCATED

出现数据截短。

不返回MYSQL_DATA_TRUNCATED，除非用mysql_options()启用了截短通报功能。返回该值时，为了确定截短的参数是哪个，可检查MYSQL_BIND参数结构的错误成员。

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SQL代码:

--创建表

CREATE TABLE userinfo

(

userid int,

username varchar(31)

);

--------------------------------------

INSERT INTO test.userinfo

(userid, username)

VALUES (1, '张三');

INSERT INTO test.userinfo

(userid, username)

VALUES (2, '李四');

INSERT INTO test.userinfo

(userid, username)

VALUES (3, '王王');

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c++代码:

#include

#include

#include

#include "mysql.h" //在工程设置中，包含在mysql的sdk中的include文件夹下

using namespace std;

string host = "localhost"; //登陆mysql使用的主机名

string user = "root"; //登陆用户

string pwd = "sa"; //填写自己数据库密码

string dbname = "test"; //您要登陆的数据库名

unsigned int port = 3306; //数据库端口，默认为3306，也可以填写你自己制定的端口

string sql = "select * from userinfo"; //sql语句，下面使用接口在c语言中执行该语句

string sqlProcess = "call getUserArea2(3)"; //sql存储过程语句

int status; //数据库执行返回的状态，sql语句执行成功返回0

int main()

{

MYSQL *mysql;

mysql = mysql_init(0); //接口，初始化

MYSQL_RES *result;

MYSQL_ROW row; //返回数据行

unsigned long length[2];

int row_count;

int int_data;

char str_data[5000];

my_bool is_null[2];

//连接数据库

if (mysql_real_connect(mysql, host.c_str(), user.c_str(), pwd.c_str(), dbname.c_str(), port, NULL, CLIENT_FOUND_ROWS | CLIENT_MULTI_STATEMENTS) == NULL)

{

cout << "connect failure!" << endl;

return 0;

}

else

{

cout << "connect success!" << endl;

}

mysql_set_character_set(mysql, "gbk");

//使用预处理

char sql[] = "select userid,username from userinfo where userid!=(?)"; //"call getUserArea(?)"; //

MYSQL_STMT *stmt = mysql_stmt_init(mysql);

if (mysql_stmt_prepare(stmt, sql, strlen(sql)))

{

printf(mysql_stmt_error(stmt));

return 0;

}

int param_count = mysql_stmt_param_count(stmt);

int t1 = 1;

MYSQL_BIND inBind;

memset(&inBind, 0, sizeof(inBind));

inBind.buffer_type = MYSQL_TYPE_LONG;

inBind.buffer = (char *)&t1;

inBind.is_null = 0;

inBind.length = 0;

if (mysql_stmt_bind_param(stmt, &inBind))

{

printf(mysql_stmt_error(stmt));

return 0;

}

if (mysql_stmt_execute(stmt))

{

printf(mysql_stmt_error(stmt));

}

MYSQL_BIND outBind[2];

memset(outBind, 0, sizeof(outBind));

//INTEGER COLUMN

outBind[0].buffer_type = MYSQL_TYPE_LONG;

outBind[0].buffer= (char *)&int_data;

outBind[0].is_null= &is_null[0];

outBind[0].length= &length[0];

//STRING COLUMN

outBind[1].buffer_type= MYSQL_TYPE_STRING;

outBind[1].buffer= (char *)str_data;

outBind[1].buffer_length= 5000;

outBind[1].is_null= &is_null[1];

outBind[1].length= &length[1];

if (mysql_stmt_bind_result(stmt, outBind))

{

fprintf(stderr, " %s\n", mysql_stmt_error(stmt));

exit(0);

}

/* Now buffer all results to client */

if (mysql_stmt_store_result(stmt))

{

fprintf(stderr, " %s\n", mysql_stmt_error(stmt));

exit(0);

}

int rows = mysql_stmt_num_rows(stmt);

for( my_ulonglong i=0; i

{

int r = mysql_stmt_fetch(stmt);

//出现数据截断。就是这里出错的....

if(r == MYSQL_DATA_TRUNCATED) {

fprintf(stderr, " %s\n", mysql_stmt_error(stmt));

}

fprintf(stdout, "column1: ");

if (is_null[0]) fprintf(stdout, " NULL\n");

else fprintf(stdout, " %d(%ld)\n", int_data, length[0]);

/* column 2 */

fprintf(stdout, "column2:");

if (is_null[1]) fprintf(stdout, " NULL\n");

else fprintf(stdout, " %s(%ld)\n", str_data, length[1]);

}

mysql_stmt_close(stmt);

return 0;

}

作者: yeerh

发布时间: 2011-01-22