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庫文件當中,與MySQL的源代碼一塊發(fā)行,用于連接到數(shù)據(jù)庫和執(zhí)行數(shù)據(jù)庫查詢。#include
#include
#include
#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;
}
//連接mysql服務(wù)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;
}
編程步驟
1 通過調(diào)用mysql_library_init(),初始化MYSQL庫
2 通過調(diào)用mysql_init()初始化連接處理程序,并通過調(diào)用mysql_real_connect()連接到服務(wù)器
3 發(fā)出SQL語句并處理其結(jié)果
4 通過調(diào)用mysql_close(),關(guān)閉與MYSQL服務(wù)器的連接
5 通過調(diào)用mysql_library_end(),結(jié)束MYSQL庫的使用
編譯需要注意的問題 問題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++的動態(tài)庫,在編譯選項中添加-lstdc++選項
問題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’
回調(diào)函數(shù)的正反向調(diào)用,需要使用到dl函數(shù)庫,在編譯選項中添加-ldl選項
問題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的動態(tài)庫用到多線程,所以編譯選項中添加-lpthread選項
4.問題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]$
缺少運行時動態(tài)庫以及數(shù)學(xué)庫,添加-lm以及-lrt選項
完整的gcc編譯命令:
gcc -o hello hello.c -I/usr/include/mysql/ -L/usr/lib/i386-linux-gnu/ -lmysqlclient -lm -ldl -lstdc++ -lpthread -lrt
一般Makefile編寫.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
$(CC) $(CFLAGS) -c $< -o $@
hello:hello.o
$(CC) $(CFLAGS) $^ $(LFLAGS) -o $@
clean:
rm -f *.o $(BIN)
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