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| //代码下载:https://github.com/yiwenshao/code_for_blog/blob/master/2017/1/MySQL的Embedded模式C接口/full.cc
#include<iostream>
#include<stdio.h>
#include<string>
#include<memory>
#include<vector>
#include<tuple>
#include <pthread.h>
#include<mysql.h>
#include<my_global.h>
#define THREAD_NUM 16
using namespace std;
static bool lib_initialized = false;
//调用出错是用到的函数
void finish_with_error(MYSQL *con){
fprintf(stderr, "%s\n", mysql_error(con));
mysql_close(con);
return;
}
//获得命令执行的结果.
void mysql_result_wrapper(MYSQL *con){
MYSQL_RES *result = mysql_store_result(con);
if(result == NULL) return;
int num_fields = mysql_num_fields(result);
if(num_fields==0) return;
MYSQL_FIELD *field;
MYSQL_ROW row;
//获得参数affected rows.
printf("%ld products updated",
(long) mysql_affected_rows(con));
while(row = mysql_fetch_row(result)){
for(int i = 0; i < num_fields; i++) {
if (i == 0)
{
while(field = mysql_fetch_field(result))
{
printf("%s ", field->name);
printf("%d ",field->type);
}
printf("\n");
}
printf("%s ", row[i] ? row[i] : "NULL");
}
//以数组的方式返回get的当前row的所有字段的长度
//const unsigned long *const l = mysql_fetch_lengths(result);
//for(int i = 0; i < num_fields; i++) {
// cout<<l[i]<<"\t"<<endl;
//}
}
printf("\n");
}
//发送单个MySQL命令
void mysql_query_wrapper(MYSQL *con,string s){
if(mysql_query(con, s.c_str())) {
finish_with_error(con);
}
mysql_result_wrapper(con);
}
//初始化MySQL
void init_mysql(){
//保证该函数只被调用一次
if (!__sync_bool_compare_and_swap(&lib_initialized, false, true)) {
return ;
}
char dir_arg[1024];
snprintf(dir_arg, sizeof(dir_arg), "--datadir=%s", "./shadow");
//第一个参数被忽略, 一般给个名字. 所有参数会复制, 所以调用以后销毁参数是可以的.用这个函数, 是为了多线程,否则mysql_init就可以了.
char *mysql_av[4]=
{ "progname",
"--skip-grant-tables",
dir_arg,
"--character-set-server=utf8"
};
//int mysql_library_init(int argc, char **argv, char **groups)
assert(0 == mysql_library_init(sizeof(mysql_av)/sizeof(mysql_av[0]),(char**) mysql_av, 0));
//多线程条件下, 每个线程在使用mysql库中的函数时, 都要调用该函数进行初始化.
assert(0 == mysql_thread_init());
}
void *thread_func(void *arg) {
int v = (long)arg;
//每个线程使用mysql相关的函数之前, 先调用该函数进行初始化.
assert(0 == mysql_thread_init());
MYSQL* mysql = mysql_init(NULL);
mysql_options(mysql, MYSQL_READ_DEFAULT_GROUP, "libmysqld_client");
mysql_options(mysql, MYSQL_OPT_USE_EMBEDDED_CONNECTION, NULL);
mysql_real_connect(mysql, NULL, NULL, NULL, "information_schema", 0, NULL, 0);
MYSQL* con = mysql;
string use="use ttddbb;";
mysql_query_wrapper(con,use);
string num = to_string(v);
string s="insert into student values("+ num+",'zhangfei')";
mysql_query_wrapper(con,s);
return (void*)0;
}
int main(){
//初始化, 只需要调用一次.
init_mysql();
assert(0 == mysql_thread_init());
MYSQL* mysql = mysql_init(NULL);
mysql_options(mysql, MYSQL_READ_DEFAULT_GROUP, "libmysqld_client");
mysql_options(mysql, MYSQL_OPT_USE_EMBEDDED_CONNECTION, NULL);
mysql_real_connect(mysql, NULL, NULL, NULL, "information_schema", 0, NULL, 0);
MYSQL* con = mysql;
string s;
s="SELECT @@sql_safe_updates";
mysql_query_wrapper(con,s);
s="create database if not exists ttddbb;";
mysql_query_wrapper(con,s);
s="use ttddbb;";
mysql_query_wrapper(con,s);
s="create table if not exists student (id integer, name varchar(20));";
mysql_query_wrapper(con,s);
pthread_t pids[THREAD_NUM];
int i;
for (i = 0; i < THREAD_NUM; i++) {
pthread_create(&pids[i], NULL, thread_func, (void*)(unsigned long)(i));
}
for (i = 0; i < THREAD_NUM; i++) {
pthread_join(pids[i], NULL);
}
s="select * from student";
mysql_query_wrapper(con,s);
return 0;
}
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