Linux下c编程sqlite3的基本语句

目录

 

Ubuntu下安装sqlite3

sqlite3的基本系统命令

sqlite3基本命令 

使用sqlite3查看已经创建的表

使用C语言的接口函数来进行对数据库的增删改查的操作 

编程示例 

测试实例

---

• Ubuntu下安装sqlite3

1. 命令行安装

   sudo apt-get install sqlite3

2. 检查是否安装成功

   //在shell界面下输入
    
   sqlite3

   

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• sqlite3的基本系统命令

1. sqlite3的系统命令是以‘.’开头的；
2. 基本命令

   .help                  //打印帮助信息
   .databases             //列出附加数据库的名称和文件
   .exit                  //退出程序
   .quit                  //退出程序
   .schema                //查看当前表结构
   .show                  //显示各种设置的当前值

   

• sqlite3基本命令 

1. 创建一个表

    create table ex (id integer, name char, tel integer);  //创建一个表

2. 插入一条数据

    insert into ex values(1001, "zhangsan", 138789);    

3. 查询数据

   select * from ex;  //查询所有数据
   
   select * from ex where id = 1001;      //按指定id的内容查询数据
   select * from ex where name = "lisi";  //按指定name的内容查询数据

4. 更新一条数据

   update ex set name = "update" where id = 1001;  //将id = 1001 的name 更新为 update
   

5. 删除一条数据

   delete from ex where id = 1001;  //删除id为1001的所有数据

• 使用sqlite3查看已经创建的表

  sqlite3 ex.db

  

• 使用C语言的接口函数来进行对数据库的增删改查的操作 

1. 创建一个表

   int sqlite_create(char *pthaname)
   {
       sqlite3*          db;
       const char*       sql_create = "create table stu (id integer, name char, score integer)";
       printf("access ok ");
       int               cmd;
   
       if (access(PATHNAME, F_OK) != 0)  //判断数据库文件是否存在
       {
   
           if (sqlite3_open(PATHNAME, &db) != SQLITE_OK) //不存在则创建
           {
               printf("Open sqlite error:%s\n", sqlite3_errmsg(db));
               return -1;
           }
           else
           {
               printf("Open sqlite success.\n");
           }       printf("access ok ");
           if (sqlite3_exec(db, sql_create, NULL, NULL, NULL)!= SQLITE_OK)
           {
               printf("Create table error:%s\n", sqlite3_errmsg(db));
               return -1;
           }
           else
           {
               printf("Create table success.\n");
           }
       }
   
       if (sqlite3_open(PATHNAME, &db) != SQLITE_OK)   //存在则直接打开，
       {
           printf("Open sqlite error:%s\n", sqlite3_errmsg(db));
           return -1;
       }
       else
       {
           printf("Open sqlite success.\n");
       }
       return 0；
   }

2. 插入一条数据

   int InsertInto_db(sqlite3* db)
   {
       int     id;
       char    name[32] = {};
       int     score;
       char    sql_insert[128] = {};
       memset(sql_insert, 0, sizeof(sql_insert));
   
       puts("Please enter id num:");
       scanf("%d", &id);
       getchar();
       puts("Please enter name:");
       scanf("%s", name);
       getchar();
       puts("Please enter score:");
       scanf("%d", &score);
       getchar();
   
       sprintf(sql_insert, "insert into stu values(%d, '%s', %d);",id, name, score);
   
       if (sqlite3_exec(db, sql_insert, NULL, NULL, NULL)!= SQLITE_OK)
       {
           printf("Insert data into table error:%s\n", sqlite3_errmsg(db));
           return -1;
       }
       else
       {
           printf("Insernt data to table success.\n");
       }
   
       return 0;
   }
   

3. 查询数据（需要使用回调函数来处理查询到的数据）

   int QueryFrom_db(sqlite3* db)
   {
       char del_sql[128] = {};
       snprintf(del_sql, 128, "select * from stu");
       if (sqlite3_exec(db, del_sql, callback, NULL, NULL)!= SQLITE_OK)
       {
           printf("Delete data from table error:%s\n", sqlite3_errmsg(db));
           return -1;
       }
       else
       {
           printf("Query  data from table success.\n");
       }
   
       return 0;
   }
   
   int callback(void* para, int f_num, char ** f_value,char** f_name) //回调函数来打印查询到的数据
   {
       int  i =0;
       for (i = 0; i < f_num; ++i)
       {
           printf("%-11s", f_value[i]);
       }
       putchar(10);
   
       return 0;
   
   }

4. 更新一条数据

   int UpdateInto_db(sqlite3* db)
   {
       char del_sql[128] = {};
       int           id  = 0;
       int        score  = 0;
       puts("Enter the id you want Update:");
       scanf("%d", &id);
       getchar();
       puts("Enter the data you want Update:");
       scanf("%d", &score);
       getchar();
       snprintf(del_sql, 128, "update stu set score = %d where id = %d",score, id);
       if (sqlite3_exec(db, del_sql, NULL, NULL, NULL)!= SQLITE_OK)
       {
           printf("Delete data from table error:%s\n", sqlite3_errmsg(db));
           return -1;
       }
       else
       {
           printf("Update data from table success.\n");
       }
   
       return 0;
   }

5. 删除一条数据

   int DeleteFrom_db(sqlite3* db)
   {
       char del_sql[128] = {};
       int           id  = 0;
       puts("Enter the id you want delete:");
       scanf("%d", &id);
       snprintf(del_sql, 128, "delete from stu where id = %d",id);
       if (sqlite3_exec(db, del_sql, NULL, NULL, NULL)!= SQLITE_OK)
       {
           printf("Delete data from table error:%s\n", sqlite3_errmsg(db));
           return -1;
       }
       else
       {
           printf("Delete data from table success.\n");
       }
   
       return 0;
   }

• 编程示例 

#include <stdio.h>
#include <string.h>
#include <sqlite3.h>
#include <stdlib.h>
#include <unistd.h>
#define  HEAD   0x5A
#define  TAG    0xfd
#define  LENGTH 0x03 

#define  PATHNAME  "/tmp/stu.db"  //设置数据库的文件路经

int InsertInto_db( sqlite3* db);
int DeleteFrom_db( sqlite3* db);
int QueryFrom_db(  sqlite3* db);
int UpdateInto_db( sqlite3* db);
int callback(void* para, int f_num, char ** f_value,char** f_name);

int sqlite_create(char *pthaname)
{
    sqlite3*          db;
    const char*       sql_create = "create table stu (id integer, name char, score integer)";
    int               cmd;

    if (access(PATHNAME, F_OK) != 0) 
    {

        if (sqlite3_open(PATHNAME, &db) != SQLITE_OK)
        {
            printf("Open sqlite error:%s\n", sqlite3_errmsg(db));
            return -1;
        }
        else 
        {
            printf("Open sqlite success.\n");
        }       printf("access ok ");
        if (sqlite3_exec(db, sql_create, NULL, NULL, NULL)!= SQLITE_OK)
        {
            printf("Create table error:%s\n", sqlite3_errmsg(db));
            return -1;
        }
        else 
        {
            printf("Create table success.\n");
        }


    }

    if (sqlite3_open(PATHNAME, &db) != SQLITE_OK)
    {
        printf("Open sqlite error:%s\n", sqlite3_errmsg(db));
        return -1;
    }
    else 
    {
        printf("Open sqlite success.\n");
    }
    while (1) 
    {
        puts("**************************************");
        printf("1: insert data, 2:delete data, 3: query data, 4: update data, 5: qiut. \n");
        puts("**************************************");
        puts("Enter cmd(1,2...)");
        scanf("%d", &cmd);

        switch (cmd) 
        {
            case 1:
                InsertInto_db(db);
                break;
            case 2:
                DeleteFrom_db(db);
                break; 
            case 3:
                QueryFrom_db(db);
                break;
            case 4:
                UpdateInto_db(db);
                break;
            case 5:
                sqlite3_close(db);
                exit(0);
            default:
                puts("Error cmd.");

        }

    }


}


int InsertInto_db(sqlite3* db)
{
    int     id;
    char    name[32] = {};
    int     score;
    char    sql_insert[128] = {};
    memset(sql_insert, 0, sizeof(sql_insert));

    puts("Please enter id num:");
    scanf("%d", &id);
    getchar();
    puts("Please enter name:");
    scanf("%s", name);
    getchar();
    puts("Please enter score:");
    scanf("%d", &score);
    getchar();

    sprintf(sql_insert, "insert into stu values(%d, '%s', %d);",id, name, score);

    if (sqlite3_exec(db, sql_insert, NULL, NULL, NULL)!= SQLITE_OK)
    {
        printf("Insert data into table error:%s\n", sqlite3_errmsg(db));
        return -1;
    }
    else
    {
        printf("Insernt data to table success.\n");
    }

    return 0;
}

int DeleteFrom_db(sqlite3* db)
{
    char del_sql[128] = {};
    int           id  = 0;
    puts("Enter the id you want delete:");
    scanf("%d", &id);
    snprintf(del_sql, 128, "delete from stu where id = %d",id);
    if (sqlite3_exec(db, del_sql, NULL, NULL, NULL)!= SQLITE_OK)
    {
        printf("Delete data from table error:%s\n", sqlite3_errmsg(db));
        return -1;
    }       
    else
    {           
        printf("Delete data from table success.\n");       
    }  

    return 0;
}
int QueryFrom_db(sqlite3* db)
{
    char del_sql[128] = {};
    snprintf(del_sql, 128, "select * from stu");
    if (sqlite3_exec(db, del_sql, callback, NULL, NULL)!= SQLITE_OK)
    {
        printf("Delete data from table error:%s\n", sqlite3_errmsg(db));
        return -1;
    }
    else
    {
        printf("Query  data from table success.\n");
    }

    return 0;
}
int callback(void* para, int f_num, char ** f_value,char** f_name)
{
    int  i =0;
    for (i = 0; i < f_num; ++i) 
    {
        printf("%-11s", f_value[i]);
    }
    putchar(10);

    return 0;

}
int UpdateInto_db(sqlite3* db)
{
    char del_sql[128] = {};
    int           id  = 0;
    int        score  = 0;  
    puts("Enter the id you want Update:");
    scanf("%d", &id);
    getchar();
    puts("Enter the data you want Update:");
    scanf("%d", &score);
    getchar();
    snprintf(del_sql, 128, "update stu set score = %d where id = %d",score, id);
    if (sqlite3_exec(db, del_sql, NULL, NULL, NULL)!= SQLITE_OK)
    {
        printf("Delete data from table error:%s\n", sqlite3_errmsg(db));
        return -1;
    }
    else
    {
        printf("Update data from table success.\n");
    }

    return 0;
}

void test()
{
    sqlite_create(PATHNAME);
}
int main(int argc, char *argv[])
{
    test();

    return 0;
}

• 测试实例

1. 插入数据

   

2. 查询数据

    3.删除数据

4.修改数据