C++访问MySQL

1.安装mysql

  sudo apt-get install mysql-server mysql-client

安装过程中会提示设置用户名和密码

2.启动mysql
  sudo /etc/init.d/mysql restart

3.安装C++开发库
  sudo apt-get install libmysqlclient-dev

4.登录mysql，并创建表

mysql -u root -p

--表maxPromised

CREATE TABLE maxPromised(id BIGINT auto_increment primary key, lock_name varchar(128), instance_no BIGINT, ballot_no BIGINT, unique uniq_lock_num(`lock_name`,`instance_no`)) engine=innodb default charset=utf8;

--表maxAccepted

CREATE TABLE maxAccepted(id BIGINT auto_increment primary key, lock_name varchar(128), instance_no BIGINT, ballot_no BIGINT, usid char(37), val_len int, val_str varchar(128),unique uniq_lock_num(`lock_name`,`instance_no`)) engine=innodb default charset=utf8;

5.代码片段

#include <mysql/mysql.h>

//连接数据库
MYSQL *conn = mysql_init(NULL);
 	
if (conn == NULL) {
	LOGGER(ERROR)<<mysql_errno(conn)<<": "<<mysql_error(conn);
 	exit(1);
 }
 	
if (mysql_real_connect(conn, "localhost", "root", "themis", "themis", 0, NULL, 0) == NULL) {
	LOGGER(ERROR)<<mysql_errno(conn)<<": "<<mysql_error(conn);
	exit(1);
}

//插入
char query[MAX_SQL_STMT_SIZE];
sprintf(query, "INSERT INTO maxPromised(lock_name, instance_no, ballot_no) VALUES(\"%s\",%lu,%lu);", 
	“field“,
	1L,
	0L
 	);
 		
if(mysql_query(acceptor->conn, query) != 0){
	LOGGER(ERROR)<<"Failed:"<<query;
}

//更新
sprintf(query, "UPDATE maxPromised set ballot_no = %lu WHERE lock_name = \"%s\" AND instance_no = %lu;",
	1,
	“field”,
	3
       );
 		
if(mysql_query(acceptor->conn, query) != 0){
	LOGGER(ERROR)<<"Failed:"<<query;

//查询数据库
MYSQL_RES *result;
MYSQL_ROW row;
	
char query[MAX_SQL_STMT_SIZE];
sprintf(query, "SELECT * FROM maxAccepted_%d", id);

mysql_query(conn, query);
result = mysql_store_result(conn);

while (result && (row = mysql_fetch_row(result))) {
	const char* field = row[1];
	long iid   = atol(row[2]);
	long bno   = atol(row[3]); 

	printf("%s, %lu, %lu\n", field, iid, bno);
 }

mysql_free_result(result);

//关闭数据库
mysql_close(conn);