1、数据库的增删改

#include <myhead.h>
int main(int argc, const char *argv[])
{
	//定义数据库句柄指针
	sqlite3 *kdb=NULL;
	//打开数据库，不存在则创建
	if(sqlite3_open("./my.db",&kdb)!=SQLITE_OK)
	{
		printf("sqlite3_open error\n");
		return -1;
	}
	printf("sqlite3_open success\n");

	//创建数据表
	//准备sql语句
	char sql[128]="create table if not exists worker(id double,name char,salary double)";	
	char *errmsg=NULL;//存放执行sql语句的错误信息
	if(sqlite3_exec(kdb,sql,NULL,NULL,&errmsg)!=SQLITE_OK)
	{
		printf("exec error:%s\n",errmsg);
		sqlite3_free(errmsg);//防止内存泄露
		errmsg=NULL;
		return -1;
	}
	//增删改查
	int key=-1;
	while(1)
	{
		printf("\t\t\t＝＝信息表＝＝\n");
		printf("\t\t1、插入信息\n");
		printf("\t\t2、删除信息\n");
		printf("\t\t3、修改信息\n");
		printf("\t\t4、退出\n");
		scanf("%d",&key);
		int id=0;;
		char name[10]="";
		int salary=0;;
		switch(key)
		{
		case 1:
			{
				printf("please enter id:");
				scanf("%d",&id);
				printf("please enter name:");
				scanf("%s",name);
				printf("please enter salary:");
				scanf("%d",&salary);
				char sq1[128]="";
				sprintf(sq1,"insert into worker(id,name,salary) values(%d,'%s',%d)",id,name,salary);
				if(sqlite3_exec(kdb,sq1,NULL,NULL,&errmsg)!=SQLITE_OK)
				{
					printf("add error\n");
					sqlite3_free(errmsg);//防止内存泄露
					errmsg=NULL;
					return -1;
				}
				printf("add success\n");
			}
			break;
		case 2:
			{
				printf("please enter id to delete:");
				scanf("%d",&id);
				char sq2[128]="";
				sprintf(sq2,"delete from worker where id=%d",id);
				if(sqlite3_exec(kdb,sq2,NULL,NULL,&errmsg)!=SQLITE_OK)
				{
					printf("delete error\n");
					sqlite3_free(errmsg);//防止内存泄露
					errmsg=NULL;
					return -1;
				}
				printf("delete success\n");
			}
			break;
		case 3:
			{
				int n=-1;
				printf("please enter 1 to modify id,2 to modify name,3 to modify salary\n");
				scanf("%d",&n);
				if(n==1)
				{
					int oldid=0;
					printf("please enter old id:");
					scanf("%d",&oldid);
					printf("please enter new id:");
					scanf("%d",&id);
					char sq3[128]="";
					sprintf(sq3,"update worker set id=%d where id=%d",id,oldid);
					if(sqlite3_exec(kdb,sq3,NULL,NULL,&errmsg)!=SQLITE_OK)
					{
						printf("modify error\n");
						sqlite3_free(errmsg);//防止内存泄露
						errmsg=NULL;
						return -1;
					}
					printf("modify success\n");
				}

				if(n==2)
				{
					printf("please enter id:");
					scanf("%d",&id);
					printf("please enter new name:");
					scanf("%s",name);
					char sq4[128]="";
					sprintf(sq4,"update worker set name='%s' where id=%d",name,id);
					if(sqlite3_exec(kdb,sq4,NULL,NULL,&errmsg)!=SQLITE_OK)
					{
						printf("modify error\n");
						sqlite3_free(errmsg);//防止内存泄露
						errmsg=NULL;
						return -1;
					}
					printf("modify success\n");
				}
				if(n==3)
				{
					printf("please enter id:");
					scanf("%d",&id);
					printf("please enter new salary:");
					scanf("%d",&salary);
					char sq5[128]="";
					sprintf(sq5,"update worker set salary=%d where id=%d",salary,id);
					if(sqlite3_exec(kdb,sq5,NULL,NULL,&errmsg)!=SQLITE_OK)
					{
						printf("modify error\n");
						sqlite3_free(errmsg);//防止内存泄露
						errmsg=NULL;
						return -1;
					}
					printf("modify success\n");
				}
			}
			break;
			}
		if(key==4)
		{
			printf("退出成功\n");
			break;
		}
	}
	//关闭数据库
	sqlite3_close(kdb);
	return 0;
}

 

2、思维导图