Linux C語言實現對MySQL數據庫中表的內容進行增刪查改操作

C API Data Structures

MYSQL

This structure represents the handler for one database connection. It is used for almost all MySQL functions. Do not try to make a copy of a MYSQL structure. There is no guarantee that such a copy will be usable.

MYSQL_RES

This structure represents the result of a query that returns rows (SELECT, SHOW, DESCRIBE, EXPLAIN). The information returned from a query is called the result set in the remainder of this section.

MYSQL_ROW

This is a type-safe representation of one row of data. It is currently implemented as an array of counted byte strings. (You cannot treat these as null-terminated strings if field values may contain binary data, because such values may contain null bytes internally.) Rows are obtained by calling mysql_fetch_row().

C API Function Overview

mysql_init():          Gets or initializes a MYSQL structure.
mysql_real_connect():  Connects to a MySQL server. 
mysql_query():         Executes an SQL query specified as a null-terminated string.
mysql_use_result():    Initiates a row-by-row result set retrieval.
mysql_fetch_row():     Fetches the next row from the result set
mysql_num_fields():    Returns the number of columns in a result set.
mysql_free_result():   Frees memory used by a result set.
mysql_store_result():  Retrieves a complete result set to the client.
mysql_num_rows():      Returns the number of rows in a result set.
mysql_close():         Closes a server connection
mysql_error():         Returns the error message for the most recently invoked MySQL function.
mysql_affected_rows(): Returns the number of rows changed/deleted/inserted by the last UPDATE, DELETE, or INSERT query.

query.c

#include <mysql/mysql.h>
#include <stdio.h>
#include <string.h>
int main(int argc,char* argv[])
{
    if(argc!=2)
    {
        printf("error args\n");
        return -1;
    }
    MYSQL *conn;     
    MYSQL_RES *res;   //保存查詢結果的指針
    MYSQL_ROW row;  
    char* server="localhost";
    char* user="root";
    char* password="123";
    char* database="test";//要訪問的數據庫名稱
    char query[300]="select * from person where name='";
    sprintf(query,"%s%s%s",query, argv[1],"'");  //SQL語句
    /* strcpy(query,"select * from Person"); */
    puts(query);     //檢查SQL語句本身有沒有語法問題
    unsigned int t,r;
    conn=mysql_init(NULL);    //獲得或初始化一個MYSQL結構
    if(!mysql_real_connect(conn,server,user,password,database,0,NULL,0))  //連接一個MySQL服務器
    {
        printf("Error connecting to database:%s\n",mysql_error(conn));
        return -1;
    }
    else
    {
        printf("Connected...\n");
    }
    //將SQL語句通過conn傳遞給數據庫
    t=mysql_query(conn,query);  //執行指定爲一個空結尾的字符串的SQL查詢
    if(t)  //t>0表示不成功
    {
        printf("Error making query:%s\n",mysql_error(conn));
    }
    else
    {

        //用mysql_num_rows可以得到查詢的結果集有幾行
        //要配合mysql_store_result使用
        //結果保存在res中
        //res = mysql_store_result(conn);   //檢索一個完整的結果集合給客戶
        //printf("mysql_num_rows=%ld\n",mysql_num_rows(res));  //返回一個結果集合中的行的數量
        
        //不保存，每次使用直接去數據庫那邊去取
        res=mysql_use_result(conn);  //初始化一個一行一行的結果集合的檢索
        row = mysql_fetch_row(res);   //從結果集合中取得下一行
        if(row == NULL)
        {
            printf("Didn't find data\n");
        }
        else
        {
            do{	
                //printf("num=%d\n",mysql_num_fields(res));//列數
                for(t=0;t<mysql_num_fields(res);t++) //返回一個結果集合中的列的數量
                {
                    printf("%8s ",row[t]);  
                }
                printf("\n");
            }while((row=mysql_fetch_row(res))!=NULL);  //從結果集合中取得下一行
        }
        mysql_free_result(res);  //釋放一個結果集合使用的內存
    }
    mysql_close(conn);  //關閉一個服務器連接
    return 0;
}

insert.c

#include <mysql/mysql.h>
#include <stdio.h>
#include <string.h>
int main(int argc,char* argv[])
{
    MYSQL *conn;
    MYSQL_RES *res;
    MYSQL_ROW row;
    char* server="localhost";
    char* user="root";
    char* password="123";
    char* database="test";
    char query[200]="insert into person(name,english,science) values('bluk',60,60)";
    int t,r;
    conn=mysql_init(NULL);
    if(!mysql_real_connect(conn,server,user,password,database,0,NULL,0))
    {
        printf("Error connecting to database:%s\n",mysql_error(conn));
    }
    else
    {
        printf("Connected...\n");
    }
    //將SQL語句通過conn傳遞給數據庫
    //執行指定爲一個空結尾的字符串的SQL查詢
    t=mysql_query(conn,query);
    if(t)   //t>0表示不成功
    {
        printf("Error making query:%s\n",mysql_error(conn));
    }else{
        printf("insert success\n");
    }
    mysql_close(conn);    //關閉一個服務器連接
    return 0;
}

update.c

#include <mysql/mysql.h>
#include <stdio.h>
#include <string.h>
int main(int argc,char* argv[])
{
    if(argc!=2)
    {
        printf("error args\n");
        return -1;
    }
    MYSQL *conn;
    MYSQL_RES *res;
    MYSQL_ROW row;
    char* server="localhost";
    char* user="root";
    char* password="123";
    char* database="test";
    char query[200]="update Person set LastName='"; 
    sprintf(query,"%s%s%s",query,argv[1],"' where personID=5");
    puts(query);
    int t,r;
    conn=mysql_init(NULL);
    if(!mysql_real_connect(conn,server,user,password,database,0,NULL,0))
    {
        printf("Error connecting to database:%s\n",mysql_error(conn));
    }
    else
    {
        printf("Connected...\n");
    }
    t=mysql_query(conn,query);
    if(t)
    {
        printf("Error making query:%s\n",mysql_error(conn));
    }
    else
    {
        printf("update success\n");
    }
    mysql_close(conn);
    return 0;
}

delete.c

#include <mysql/mysql.h>
#include <stdio.h>
#include <string.h>
int main(int argc,char* argv[])
{
    MYSQL *conn;
    MYSQL_RES *res;
    MYSQL_ROW row;
    char* server="localhost";
    char* user="root";
    char* password="123";
    char* database="test";
    char query[200]="delete from Person where FirstName='xiong'";
    int t,r;
    conn=mysql_init(NULL);
    if(!mysql_real_connect(conn,server,user,password,database,0,NULL,0))
    {
        printf("Error connecting to database:%s\n",mysql_error(conn));
    }
    else
    {
        printf("Connected...\n");
    }
    t=mysql_query(conn,query);
    if(t)
    {
        printf("Error making query:%s\n",mysql_error(conn));
    }
    else
    {
        printf("delete success,delete row=%ld\n",(long)mysql_affected_rows(conn));
    }
    mysql_close(conn);
    return 0;
}