C语言对Mysql函数操作
数据类型
-
MYSQL
MYSQL结构代表一个数据库连接句柄，包含有关服务器的连接状态的信息，几乎所有函数都是用到它
typedef struct st_mysql
{
NET net; /* Communication parameters /
unsigned char connector_fd; / ConnectorFd for SSL /
char host,user,passwd,unix_socket,server_version,host_info;
char *info, *db;
struct charset_info_st *charset;
MYSQL_FIELD fields;
MEM_ROOT field_alloc;
my_ulonglong affected_rows;
my_ulonglong insert_id; / id if insert on table with NEXTNR /
my_ulonglong extra_info; / Not used /
unsigned long thread_id; / Id for connection in server /
unsigned long packet_length;
unsigned int port;
unsigned long client_flag,server_capabilities;
unsigned int protocol_version;
unsigned int field_count;
unsigned int server_status;
unsigned int server_language;
unsigned int warning_count;
struct st_mysql_options options;
enum mysql_status status;
my_bool free_me; / If free in mysql_close /
my_bool reconnect; / set to 1 if automatic reconnect *//* session-wide random string */
char scramble[SCRAMBLE_LENGTH+1];/*
Set if this is the original connection, not a master or a slave we have
added though mysql_rpl_probe() or mysql_set_master()/ mysql_add_slave()
/
my_bool rpl_pivot;
/
Pointers to the master, and the next slave connections, points to
itself if lone connection.
/
struct st_mysql master, *next_slave;struct st_mysql* last_used_slave; /* needed for round-robin slave pick /
/ needed for send/read/store/use result to work correctly with replication /
struct st_mysql last_used_con;LIST stmts; / list of all statements */
const struct st_mysql_methods *methods;
void thd;
/
Points to boolean flag in MYSQL_RES or MYSQL_STMT. We set this flag
from mysql_stmt_close if close had to cancel result set of this object.
*/
my_bool unbuffered_fetch_owner;
/ needed for embedded server - no net buffer to store the 'info' */
char *info_buffer;
void *extension;
} MYSQL; -
MYSQL_RES
MYSQL_RES结构代表返回行的查询结果（SELECT、SHOW、DESCRIBE等），从数据库读取数据，最后就是从MYSQL_RES中读取数据。 MYSQL_RES定义如下：
typedef struct st_mysql_res { my_ulonglong row_count; MYSQL_FIELD *fields; MYSQL_DATA *data; MYSQL_ROWS *data_cursor; unsigned long *lengths; /* column lengths of current row */ MYSQL *handle; /* for unbuffered reads */ const struct st_mysql_methods *methods; MYSQL_ROW row; /* If unbuffered read */ MYSQL_ROW current_row; /* buffer to current row */ MEM_ROOT field_alloc; unsigned int field_count, current_field; my_bool eof; /* Used by mysql_fetch_row */ /* mysql_stmt_close() had to cancel this result */ my_bool unbuffered_fetch_cancelled; void *extension; } MYSQL_RES;
数据库函数
1 mysql_real_connect
函数原型如下：
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);
例子：
#include <stdio.h>
#include <mysql.h>
int main(int argc, const char *argv[])
{
MYSQL mysql;
if (NULL == mysql_init(&mysql)) { //分配和初始化MYSQL对象
printf("mysql_init(): %s\n", mysql_error(&mysql));
return -1;
}
//尝试与运行在主机上的MySQL数据库引擎建立连接
if (NULL == mysql_real_connect(&mysql,
"localhost",
"root",
"shallnet",
"db_users",
0,
NULL,
0)) {
printf("mysql_real_connect(): %s\n", mysql_error(&mysql));
return -1;
}
printf("Connected MySQL successful! \n");
mysql_close(&mysql);
return 0;
}
2 数据查询语句函数mysql_query
函数原型
int STDCALL mysql_query(MYSQL *mysql, const char *q);
查询的例子：
#include <stdio.h>
#include <mysql.h>
#include <string.h>
int main(int argc, const char *argv[])
{
MYSQL mysql;
MYSQL_RES *res = NULL;
MYSQL_ROW row;
char *query_str = NULL;
int rc, i, fields;
int rows;
if (NULL == mysql_init(&mysql)) {
printf("mysql_init(): %s\n", mysql_error(&mysql));
return -1;
}
if (NULL == mysql_real_connect(&mysql,
"localhost",
"root",
"shallnet",
"db_users",
0,
NULL,
0)) {
printf("mysql_real_connect(): %s\n", mysql_error(&mysql));
return -1;
}
printf("1. Connected MySQL successful! \n");
query_str = "select * from tb_users";
rc = mysql_real_query(&mysql, query_str, strlen(query_str));
if (0 != rc) {
printf("mysql_real_query(): %s\n", mysql_error(&mysql));
return -1;
}
res = mysql_store_result(&mysql);
if (NULL == res) {
printf("mysql_restore_result(): %s\n", mysql_error(&mysql));
return -1;
}
rows = mysql_num_rows(res);
printf("The total rows is: %d\n", rows);
fields = mysql_num_fields(res);
printf("The total fields is: %d\n", fields);
while ((row = mysql_fetch_row(res))) {
for (i = 0; i < fields; i++) {
printf("%s\t", row[i]);
}
printf("\n");
}
mysql_close(&mysql);
return 0;
}
插入删除的例子：
#include <stdio.h>
#include <mysql.h>
#include <string.h>
int main(int argc, const char *argv[])
{
MYSQL mysql;
MYSQL_RES *res = NULL;
MYSQL_ROW row;
char *query_str = NULL;
int rc, i, fields;
int rows;
if (NULL == mysql_init(&mysql)) {
printf("mysql_init(): %s\n", mysql_error(&mysql));
return -1;
}
if (NULL == mysql_real_connect(&mysql,
"localhost",
"root",
"shallnet",
"db_users",
0,
NULL,
0)) {
printf("mysql_real_connect(): %s\n", mysql_error(&mysql));
return -1;
}
printf("1. Connected MySQL successful! \n");
query_str = "select * from tb_users";
rc = mysql_real_query(&mysql, query_str, strlen(query_str));
if (0 != rc) {
printf("mysql_real_query(): %s\n", mysql_error(&mysql));
return -1;
}
res = mysql_store_result(&mysql);
if (NULL == res) {
printf("mysql_restore_result(): %s\n", mysql_error(&mysql));
return -1;
}
rows = mysql_num_rows(res);
printf("The total rows is: %d\n", rows);
fields = mysql_num_fields(res);
printf("The total fields is: %d\n", fields);
while ((row = mysql_fetch_row(res))) {
for (i = 0; i < fields; i++) {
printf("%s\t", row[i]);
}
printf("\n");
}
mysql_close(&mysql);
return 0;
}
gcc具体的编译方法：gcc ***.c -o *** -lmysqlclient
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