【C语言+sqlite3 API接口】实现水果店管理

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实验内容：

假如我家开了个水果超市，有以下水果，想实现自动化管理，扫描二维码就能知道当前的水果状态，进货几天了，
好久需要再次进货，那些水果畅销，那些水果不畅销，那些水果春夏秋冬的价格波动，好，那么现在我想将
这些信息保存在数据库中，那么我应该怎么做？

超市每天水果都有进货和卖出嘛，水果的价格随着季节和天气也会有波动，顾客也会看一下每天水果的价格的嘛，
所以要求，利用数据库完成水果店各种水果的增（进货）删（卖出）改（波动）查（看价格）功能。
并将进出货的时间和顾客光顾的时间记录到数据库中保存。

实现流程：

首先创建一张数据表fruit，除了需要指定每条记录的唯一标识id外，还要有水果品类(name)、存量(weight)、价格(price)、最近交易时间(time)等字段。每一次操作，都会改变表中的数据内容，这些我们通过API来实现：各种水果的增（进货）删（卖出）改（波动）查（看价格）功能。并将进出货的时间和顾客光顾的时间记录到数据库中保存。

代码实现：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sqlite3.h>
#include <time.h>#define  DATABASE  "mysql.db"
#define TABLES "fruit"
#define  N  128int do_insert(sqlite3 *db,char *buf);
int do_update_weight(sqlite3 *db,char *buf);
int do_update_price(sqlite3 *db);
int do_query(sqlite3 *db);
int callback(void *arg, int f_num, char ** f_value, char ** f_name);int main(int argc, const char *argv[])
{sqlite3 *db;char *errmsg;int n;char sql[128] = {};char buf[128] = {};time_t t;struct tm *tp;if(sqlite3_open(DATABASE, &db) != SQLITE_OK){printf("%s\n", sqlite3_errmsg(db));return -1;}else{printf("open DATABASE success.\n");}sprintf(sql,"create table if not exists '%s' (id integer primary key autoincrement,name char,weight float,price float,time char);",TABLES);if(sqlite3_exec(db, sql,NULL, NULL, &errmsg) != SQLITE_OK){printf("%s\n", errmsg);}else{printf("Create or open table success.\n");}time(&t);tp = localtime(&t);sprintf(buf,"%d-%02d-%02d %02d:%02d:%02d\n",tp->tm_year+1900, tp->tm_mon+1,tp->tm_mday, tp->tm_hour, tp->tm_min, tp->tm_sec);printf("%s",buf);while(1){puts("-----------------------------------------");do_query(db);puts("-----------------------------------------");puts("");printf("********************************************\n");printf("1: insert  2:query  3:trade 4:update 5:quit\n");printf("********************************************\n");printf("Please select:");scanf("%d", &n);switch(n){case 1:do_insert(db,buf);break;case 2:do_query(db);break;case 3:do_update_weight(db,buf);break;case 4:do_update_price(db);break;case 5:printf("main exit.\n");sqlite3_close(db);exit(0);break;default :printf("Invalid data n.\n");}}return 0;
}int do_insert(sqlite3 *db,char *buf)
{char name[32] = {};float weight;float price;char sql[N] = {};char *errmsg;printf("Input fruit name:");scanf("%s", name);getchar();printf("Input weight:");scanf("%f", &weight);printf("Input price:");scanf("%f", &price);sprintf(sql, "insert into '%s' (name,weight,price,time)values('%s', '%.3f', '%.3f','%s')",TABLES, name, weight, price,buf);if(sqlite3_exec(db, sql, NULL, NULL, &errmsg) != SQLITE_OK){printf("%s\n", errmsg);}else{printf("Insert done.\n");}return 0;
}int do_update_weight(sqlite3 *db,char *buf)
{int id;char sql[N] = {};char *errmsg;float weight;printf("Input id:");scanf("%d", &id);printf("Input weight:");scanf("%f", &weight);sprintf(sql, "update '%s' set weight='%f',time='%s' where id=%d",TABLES, weight,buf,id);if(sqlite3_exec(db, sql, NULL, NULL, &errmsg) != SQLITE_OK){printf("%s\n", errmsg);}else{printf("Delete done.\n");}return 0;
}int do_update_price(sqlite3 *db)
{float price;int id;char sql[N] = {};char *errmsg;printf("Input id:");scanf("%d", &id);printf("Input alter price:");scanf("%f", &price);sprintf(sql, "update '%s' set price='%f' where id=%d",TABLES , price,id);if(sqlite3_exec(db, sql, NULL, NULL, &errmsg) != SQLITE_OK){printf("%s\n", errmsg);}else{printf("update done.\n");}return 0;
}int callback(void *arg, int f_num, char ** f_value, char ** f_name)
{int i = 0;for(i = 0; i < f_num; i++){//	printf("%-8s %s", f_value[i], f_name[i]);printf("%-8s", f_value[i]);}putchar(10);puts("-----------------------------------------");return 0;
}int do_query(sqlite3 *db)
{char *errmsg;char sql[N] = {};sprintf(sql,"select * from '%s';",TABLES);if(sqlite3_exec(db, sql, callback,NULL , &errmsg) != SQLITE_OK){printf("%s", errmsg);}else{printf("select done.\n");}return 0;
}