c语言连接mysql(入门)_MySQL入门之C语言操作MySQL

基本概念

C APIs包含在mysqlclient库文件当中，与MySQL的源代码一块发行，用于连接到数据库和执行数据库查询。#include

#include

int main()

{

int ret = 0;

MYSQL mysql;

MYSQL *con = NULL;

con = mysql_init(&mysql);

if (con == NULL)

{

ret = mysql_errno(&mysql);

printf("func mysql_init() err :%d\n", ret);

return ret;

}

//连接mysql服务器

//MYSQL *mysql_real_connect(MYSQL *mysql, const char *host, const char *user, const char *passwd,

//const char *db, unsigned int port, const char *unix_socket, unsigned long client_flag) ;

con = mysql_real_connect(&mysql, "localhost", "root", "123456", "mydb2", 0, NULL, 0 );

if (con == NULL)

{

ret = mysql_errno(&mysql);

printf("func mysql_real_connect() err :%d\n", ret);

return ret;

}

else

{

printf("func mysql_real_connect() ok\n");

}

mysql_close(&mysql);

return ret;

}

编程步骤

1 通过调用mysql_library_init(),初始化MYSQL库

2 通过调用mysql_init()初始化连接处理程序，并通过调用mysql_real_connect()连接到服务器

3 发出SQL语句并处理其结果

4 通过调用mysql_close()，关闭与MYSQL服务器的连接

5 通过调用mysql_library_end()，结束MYSQL库的使用

编译需要注意的问题问题1：

[mysql01@localhost dm01]$ gcc -o dm11_hello dm11_hello.c -I/usr/include/ -L/usr/lib64/mysql/ -lmysqlclient

/usr/lib64/mysql//libmysqlclient.a(net_serv.cc.o):(.data.DW.ref.__gxx_personality_v0[DW.ref.__gxx_personality_v0]+0x0): undefined reference to __gxx_personality_v0'

/usr/lib64/mysql//libmysqlclient.a(password.c.o): In functionscramble_323’:

需要用到c++的动态库，在编译选项中添加-lstdc++选项

问题2

/usr/lib64/mysql//libmysqlclient.a(dso_dlfcn.o): In function dlfcn_globallookup':

dso_dlfcn.c:(.text+0x31): undefined reference todlopen’

dso_dlfcn.c:(.text+0x44): undefined reference to dlsym'

dso_dlfcn.c:(.text+0x4f): undefined reference todlclose’

/usr/lib64/mysql//libmysqlclient.a(dso_dlfcn.o): In function dlfcn_pathbyaddr':

dso_dlfcn.c:(.text+0xa0): undefined reference todladdr’

dso_dlfcn.c:(.text+0x101): undefined reference to dlerror'

/usr/lib64/mysql//libmysqlclient.a(dso_dlfcn.o): In functiondlfcn_bind_func’:

dso_dlfcn.c:(.text+0x464): undefined reference to `dlsym’

回调函数的正反向调用，需要使用到dl函数库，在编译选项中添加-ldl选项

问题3

thread_mutex_trylock’

/usr/lib64/mysql//libmysqlclient.a(my_thr_init.c.o): In function my_thread_global_end':

/pb2/build/sb_0-12734909-1406113305.48/rpm/BUILD/mysqlcom-pro-5.6.20/mysqlcom-pro-5.6.20/mysys/my_thr_init.c:214: undefined reference topthread_key_delete’

/pb2/build/sb_0-12734909-1406113305.48/rpm/BUILD/mysqlcom-pro-5.6.20/mysqlcom-pro-5.6.20/mysys/my_thr_init.c:217: undefined reference to pthread_mutexattr_destroy'

/pb2/build/sb_0-12734909-1406113305.48/rpm/BUILD/mysqlcom-pro-5.6.20/mysqlcom-pro-5.6.20/mysys/my_thr_init.c:220: undefined reference topthread_mutexattr_destroy’

MySQL的动态库用到多线程，所以编译选项中添加-lpthread选项

4.问题4

[mysql01@localhost dm01]$ gcc -o dm11_hello dm11_hello.c -I/usr/include/ -L/usr/lib64/mysql/ -lmysqlclient -ldl -lstdc++ -lpthread

/usr/lib64/mysql//libmysqlclient.a(my_getsystime.c.o): In function my_getsystime':

/pb2/build/sb_0-12734909-1406113305.48/rpm/BUILD/mysqlcom-pro-5.6.20/mysqlcom-pro-5.6.20/mysys/my_getsystime.c:44: undefined reference toclock_gettime’

collect2: ld 返回 1

[mysql01@localhost dm01]$

缺少运行时动态库以及数学库，添加-lm以及-lrt选项

完整的gcc编译命令：

gcc -o hello hello.c -I/usr/include/mysql/ -L/usr/lib/i386-linux-gnu/ -lmysqlclient -lm -ldl -lstdc++ -lpthread -lrt

一般Makefile编写.PHONY:clean all

CC=gcc

CFLAGS=-Wall -g

LFLAGS=-L/usr/lib/i386-linux-gnu/ -lmysqlclient -ldl -lpthread -lm -lrt -lstdc++

BIN=hello

all:$(BIN)

%.o:%.c