C 连接MySQL
1. 必须安装的软件
yum -y install gcc
yum -y install mysql-server
yun -y install mysql-devel
yum install -y zlib-devel
2. 连接数据库
#include
#include
#include
int main() {
MYSQL *conn_ptr;
conn_ptr = mysql_init(NULL);
if (!conn_ptr) {
printf("mysql_init failed\n");
return EXIT_FAILURE;
}
conn_ptr = mysql_real_connect(conn_ptr, "localhost", "root", "123456", "student", 0, NULL, 0);
//root 为用户名 123456为密码 test为要连接的database
if (conn_ptr) {
printf("Connection success\n");
} else {
printf("Connection failed\n");
}
mysql_close(conn_ptr);
return EXIT_SUCCESS;
}
3. 编译方法
gcc -g -o bbb -I/usr/include/mysql/ bbb.c -L/usr/lib64/mysql/ -lmysqlclient -lz
参数说明：-I（大写的i） 表示要连接的头文件目录，因为使用了
如果不用-I -L ，可能导致找不到头文件 或者 函数未定义的错误
如果出现错误error while loading shared libraries，那是因为.so没有被系统载入，解决办法如下
vi /etc/ld.so.conf // 打开ld.so.conf文件，增加.so文件的路径，比如/usr/local/mysql/lib/
ldconfig //重新加载.so文件
4. 查询代码
#include
#include
#includeint main() {
MYSQL *conn_ptr;
MYSQL_RES *res_ptr;
MYSQL_ROW sqlrow;
MYSQL_FIELD *fd;
int res, i, j;
conn_ptr = mysql_init(NULL);
if (!conn_ptr) {
return EXIT_FAILURE;
}
conn_ptr = mysql_real_connect(conn_ptr, "localhost", "root", "123456", "student", 0, NULL, 0);
if (conn_ptr) {
res = mysql_query(conn_ptr, "select id,name,serial,address from information"); //查询语句
if (res) {
printf("SELECT error:%s\n",mysql_error(conn_ptr));
} else {
res_ptr = mysql_store_result(conn_ptr); //取出结果集
if(res_ptr) {
printf("%lu Rows\n",(unsigned long)mysql_num_rows(res_ptr));
j = mysql_num_fields(res_ptr);
while((sqlrow = mysql_fetch_row(res_ptr))) { //依次取出记录
for(i = 0; i < j; i++)
printf("%s\t", sqlrow[i]); //输出
printf("\n");
}
if (mysql_errno(conn_ptr)) {
fprintf(stderr,"Retrive error:s\n",mysql_error(conn_ptr));
}
}
mysql_free_result(res_ptr);
}
} else {
printf("Connection failed\n");
}
mysql_close(conn_ptr);
return EXIT_SUCCESS;
}
5. 插入更新及删除
#include
#include
#include
int main() {
MYSQL *conn_ptr;
int res;
conn_ptr = mysql_init(NULL);
if (!conn_ptr) {
printf("mysql_init failed\n");
return EXIT_FAILURE;
}
conn_ptr = mysql_real_connect(conn_ptr, "localhost", "root", "123456", "student", 0, NULL, 0);
if (conn_ptr) {
//insert into information values(1,"wk","123","nmg");
res = mysql_query(conn_ptr, "insert into information values(2,'Ann','555','sd')"); //可以把insert语句替换成delete或者update语句，都一样的
// res = mysql_query(conn_ptr, "delete from user where name = 'Ann' and age < 10");
if (!res) { //输出受影响的行数
printf("Inserted %lu rows\n",(unsigned long)mysql_affected_rows(conn_ptr));
} else { //打印出错误代码及详细信息
fprintf(stderr, "Insert error %d: %sn",mysql_errno(conn_ptr),mysql_error(conn_ptr));
}
} else {
printf("Connection failed\n");
}
mysql_close(conn_ptr);
return EXIT_SUCCESS;
}