//在工程设置-》链接》库模块中添加 libmysql.lib
#include <stdio.h>
#include <time.h>
#include <string.h>
#include <winsock.h>
#include "E:\wamp\bin\mysql\mysql5.5.8\include\mysql.h"
void main(){
MYSQL *conn
MYSQL_RES *res
MYSQL_ROW row
char *server ="localhost"
char *user ="root"
char *password=""
char *database="test"
char sql[1024]="select * from chinaren"
conn=mysql_init(NULL)
if(!mysql_real_connect(conn,server,user,password,database,0,NULL,0)){
fprintf(stderr,"%s\n",mysql_error(conn))
exit(1)
}
if(mysql_query(conn,sql)){
fprintf(stderr,"%s\n",mysql_error(conn))
exit(1)
}
res=mysql_use_result(conn)
while((row = mysql_fetch_row(res))!=NULL){
printf("%s\n",row[2])
}
mysql_free_result(res)
mysql_close(conn)
}
===============================
#if defined(_WIN32) || defined(_WIN64) //为了支持windows平台上的编译
#include <windows.h>
#endif
#include <stdio.h>
#include <stdlib.h>
#include "mysql.h"
//定义数据库操作的宏,也可以不定义留着后面直接写进代码
#define SELECT_QUERY "show tables"
int main(int argc, char **argv) //char **argv 相当于 char *argv[]
{
MYSQL mysql,*handle //定义数据库连接的句柄,它被用于几乎所有的MySQL函数
MYSQL_RES *result //查询结果集,结构类型
MYSQL_FIELD *field//包含字段信息的结构
MYSQL_ROW row //存放一行查询结果的字符串数组
char querysql[160] //存放查询sql语句字符串
//初始化
mysql_init(&mysql)
//连接数据库
if (!(handle = mysql_real_connect(&mysql,"localhost","user","pwd","dbname",0,NULL,0))) {
fprintf(stderr,"Couldn't connect to engine!\n%s\n\n",mysql_error(&mysql))
}
sprintf(querysql,SELECT_QUERY,atoi(argv[1]))
//查询数据库
if(mysql_query(handle,querysql)) {
fprintf(stderr,"Query failed (%s)\n",mysql_error(handle))
}
//存储结果集
if (!(result=mysql_store_result(handle))) {
fprintf(stderr,"Couldn't get result from %s\n", mysql_error(handle))
}
printf("number of fields returned: %d\n",mysql_num_fields(result))
//读取结果集的内容
while (row = mysql_fetch_row(result)) {
printf("table: %s\n",(((row[0]==NULL)&&(!strlen(row[0]))) ? "NULL" : row[0]) )
}
//释放结果集
mysql_free_result(result)
//关闭数据库连接
mysql_close(handle)
system("PAUSE")
//为了兼容大部分的编译器加入此行
return 0
}
Mysql C API编程步骤1、首先我们要包含mysql的头文件,并链接mysql动态库。即添加以下语句:
#include <WinSock2.h>// 进行网络编程需要winsock2.h
#include <mysql.h>
#pragma comment(lib, “libmysql.lib”)
2、创建MYSQL变量。如:
MYSQL mysql
3、初始化MYSQL变量。
mysql_init(&mysql)
4、调用mysql_real_connect函数连接Mysql数据库。mysql_real_connect函数的原型如下:
MYSQL * STDCALL 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 clientflag)
参数说明:mysql–前面定义的MYSQL变量;host–MYSQL服务器的地址;user–登录用户名;passwd–登录密码;db–要连接的数据库;port–MYSQL服务器的TCP服务端口;unix_socket–unix连接方式,为NULL时表示不使用socket或管道机制;clientflag–Mysql运行为ODBC数据库的标记,一般取0。连接失败时该函数返回0。
5、调用mysql_real_query函数进行数据库查询。mysql_real_query函数的原型如下:
int STDCALL mysql_real_query(MYSQL *mysql, const char *q, unsigned long length)
参数说明:mysql–前面定义的MYSQL变量;q–SQL查询语句;length–查询语句的长度。
查询成功则该函数返回0。
6、通过调用mysql_store_result或mysql_use_result函数返回的MYSQL_RES变量获取查询结果数据。
两个函数的原型分别为:
MYSQL_RES * STDCALL mysql_store_result(MYSQL *mysql)
MYSQL_RES * STDCALL mysql_use_result(MYSQL *mysql)
这两个函数分别代表了获取查询结果的两种方式。第一种,调用mysql_store_result函数将从Mysql服务器查询的所有数据都存储到客户端,然后读取;第二种,调用mysql_use_result初始化检索,以便于后面一行一行的读取结果集,而它本身并没有从服务器读取任何数据,这种方式较之第一种速度更快且所需内存更少,但它会绑定服务器,阻止其他线程更新任何表,而且必须重复执行mysql_fetch_row读取数据,直至返回NULL,否则未读取的行会在下一次查询时作为结果的一部分返回,故经常我们使用mysql_store_result。
7、调用mysql_fetch_row函数读取结果集数据。
上述两种方式最后都是重复调用mysql_fetch_row函数读取数据。mysql_fetch_row函数的原型如下:
MYSQL_ROW STDCALL mysql_fetch_row(MYSQL_RES *result)
参数result就是mysql_store_result或mysql_use_result的返回值。
该函数返回MYSQL_ROW型的变量,即字符串数组,假设为row,则row〔i〕为第i个字段的值。当到结果集尾部时,此函数返回NULL。
8、结果集用完后,调用mysql_free_result函数释放结果集,以防内存泄露。mysql_free_result函数的原型如下:
void STDCALL mysql_free_result(MYSQL_RES *result)
9、不再查询Mysql数据库时,调用mysql_close函数关闭数据库连接。mysql_close函数的原型为:
void STDCALL mysql_close(MYSQL *sock)
#ifndef ___LIB_DB___#define ___LIB_DB___
extern int DB_Open(char * dbcn, char * usr, char * pwd)
extern int DB_Exec(char * sql)
extern void * DB_Query(char *sql, const char *fmt, ...)
extern int DB_Next(void * hRecordset)
extern void DB_CleanQuery(void *hRecordset)
extern int DB_Close(void)
#endif
#ifdef WIN32
#include <windows.h>
#include <odbcinst.h>
#include <sqlext.h>
#else
#include <mysql.h>
#include <unistd.h>
#define SQLHANDLE static MYSQL
#endif
#include <stdarg.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
SQLHANDLE hDBEnv, hDBC
int DB_Open(char * dbcn, char * usr, char * pwd)
{
int r
#ifdef WIN32
r = SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &hDBEnv)
if(r) return 0
r = SQLSetEnvAttr(hDBEnv,SQL_ATTR_ODBC_VERSION,
(void*)SQL_OV_ODBC3,0)
if(r) return 0
r = SQLAllocHandle(SQL_HANDLE_DBC, hDBEnv, &hDBC)
if(r) return 0
r = SQLConnect(hDBC,
(unsigned char *)dbcn, strlen(dbcn),
(unsigned char *)usr, strlen(usr),
(unsigned char *)pwd, strlen(pwd))
return r==SQL_SUCCESS || r==SQL_SUCCESS_WITH_INFO
#else
mysql_init(&hDBC)
MYSQL * rx = mysql_real_connect(
&hDBC, dbcn, usr, pwd, NULL, 0, NULL, 0)
if(!rx) return 0
return 1
#endif
}//end DB_Open
int DB_Exec(char * sql)
{
#ifdef WIN32
SQLHANDLE hStatement = NULL
SQLAllocHandle(SQL_HANDLE_STMT, hDBC, &hStatement)
SQLExecDirect(hStatement,(unsigned char *)sql, strlen(sql))
SQLCloseCursor(hStatement)
SQLFreeHandle(SQL_HANDLE_STMT, hStatement)
hStatement = NULL
#else
mysql_real_query (&hDBC, sql, strlen(sql))
#endif
return 1
}//end DB_Exec
int DB_Close(void)
{
#ifdef WIN32
SQLDisconnect(hDBC)
SQLFreeHandle(SQL_HANDLE_DBC, hDBC)
SQLFreeHandle(SQL_HANDLE_ENV, hDBEnv)
#else
mysql_close(&hDBC)
#endif
return 1
}//DB_Close()
#ifndef WIN32
typedef struct tagMySQLRecordset {
MYSQL_RES * hRecord
void * * row
int * size
int cols
} MYSQLRecordset
#endif
void DB_CleanQuery(void *hRecordset)
{
if(!hRecordset) return
#ifdef WIN32
__try {
SQLCloseCursor(hRecordset)
SQLFreeHandle(SQL_HANDLE_STMT, hRecordset)
hRecordset = NULL
}__finally{
return
}//end try
#else
MYSQLRecordset * hRec = (MYSQLRecordset *) hRecordset
mysql_free_result (hRec->hRecord)
free(hRec->row) hRec->row = NULL
free(hRec->size)hRec->size = NULL
free(hRec)hRec = NULL
#endif
}//end DB_CleanQuery
int DB_Next(void * hRecordset)
{
int r=0if(!hRecordset) return 0
#ifdef WIN32
r = SQLFetch(hRecordset)
r = r == SQL_SUCCESS || r == SQL_SUCCESS_WITH_INFO
if(!r) {
DB_CleanQuery(hRecordset)
}//end if
#else
MYSQLRecordset * hRec = (MYSQLRecordset *) hRecordset
MYSQL_ROW row = mysql_fetch_row (hRec->hRecord)
if(row) {
for(int i=0i<hRec->colsi++) {
memcpy(hRec->row[i], row[i], hRec->size[i])
}//next i
r = 1
}else{
DB_CleanQuery(hRecordset)
r = 0
}//end if
#endif
return r
}//end DB_Next
int DB_params_count(const char * fmt)
{
int i=0, j=0
while(fmt[i]) {
if(fmt[i]=='%') j++
i++
}//end while
return j
}//end DB_params_count
void * DB_Query(char *sql, const char *fmt, ...)
{
int r=0
int cols = DB_params_count(fmt)
if(cols<1) return NULL
#ifdef WIN32
SQLHANDLE hStatement = NULL
SQLAllocHandle(SQL_HANDLE_STMT, hDBC, &hStatement)
r = SQLExecDirect(hStatement,(unsigned char *)sql, strlen(sql))
r = r==SQL_SUCCESS || r == SQL_SUCCESS_WITH_INFO
if(!r) {
return NULL
}//end if
#else
r = mysql_real_query (&hDBC, sql, strlen(sql))
if(r) return NULL
MYSQL_RES * rec = NULL
rec = mysql_store_result (&hDBC)
if(!rec) return NULL
MYSQLRecordset * hStatement
= (MYSQLRecordset *)malloc(sizeof(MYSQLRecordset))
if(!hStatement) return NULL
memset(hStatement, 0, sizeof(MYSQLRecordset))
hStatement->hRecord = rec
hStatement->cols = cols
hStatement->row = (void **)malloc(cols * sizeof(void *))
memset(hStatement->row, 0, cols * sizeof(void *))
hStatement->size = (int *)malloc(cols * sizeof(int))
memset(hStatement->size, 0, cols * sizeof(int))
#endif
va_list apva_start(ap, fmt)
void * varchar buf[32]
int i=0,j=0,k=0,sz=0char c=0
int len = strlen(fmt)int bad=1
#ifdef WIN32
int col=1
#else
int col=0
#endif
while(fmt[i]) {
c = fmt[i++]
if(c != '%') continue
c = fmt[i++]
var = va_arg(ap, void *)
if(c == 'd') {
#ifdef WIN32
SQLBindCol(hStatement, col, SQL_C_SLONG, var, 4,NULL)
#else
hStatement->row[col] = var
hStatement->size[col] = sizeof(long)
#endif
col++
continue
}//end if
if(c == 'f') {
#ifdef WIN32
SQLBindCol(hStatement, col, SQL_C_FLOAT, var, 4,NULL)
#else
hStatement->row[col] = var
hStatement->size[col] = sizeof(float)
#endif
col++
continue
}//end if
memset(buf, 0, 32)bad=1
for(j=i-1j<lenj++) {
c = fmt[j]
if(c>='0' &&c<='9') buf[j-i+1]=c
if(c=='s') {bad=0k=j+1break}
}//next j
if(bad) return NULL
sscanf(buf, "%d", &sz)
#ifdef WIN32
SQLBindCol(hStatement, col, SQL_C_CHAR, var, sz, NULL)
#else
hStatement->row[col] = var
hStatement->size[col] = sz
#endif
col++
i = k
}//end while
va_end(ap)
return hStatement
}//end DB_Rec