Linux中数据库sqlite3的基本命令的使用

news2025/1/23 6:14:56

                    
                        
                    
                    数据库概念介绍 
数据库安装 
首先将本地的三个sqlite3安装包移动到共享文件夹然后在移动到自己创建的文件夹中如下：
 
然后对安装包进行解压如下：sudo dpkg -i  *.deb
 
检查是否安装成功sqlite
 
 
数据库命令 
系统命令 ， 都以’.'开头
 .exit
 .quit
 .table 查看表
 .schema 查看表的结构
sql语句， 都以‘;’结尾
 1-- 创建一张表
 create table stuinfo(id integer, name text, age integer, score float);
 2-- 插入一条记录
 insert into stuinfo values(1001, ‘zhangsan’, 18, 80);
 insert into stuinfo (id, name, score) values(1002, ‘lisi’, 90);
 3-- 查看数据库记录
 select * from stuinfo;
 select * from stuinfo where score = 80;
 select * from stuinfo where score = 80 and name= ‘zhangsan’;
 select * from stuinfo where score = 80 or name=‘wangwu’;
 select name,score from stuinfo; 查询指定的字段
 select * from stuinfo where score >= 85 and score < 90;
 4-- 删除一条记录
 delete from stuinfo where id=1003 and name=‘zhangsan’;
 5-- 更新一条记录
 update stuinfo set age=20 where id=1003;
 update stuinfo set age=30, score = 82 where id=1003;
 6-- 删除一张表
 drop table stuinfo;
 7-- 增加一列
 alter table stuinfo add column sex char;
 8-- 删除一列
 create table stu as select id, name, score from stuinfo;
 drop table stuinfo;
 alter table stu rename to stuinfo;
数据库设置主键：
 create table info(id integer primary key autoincrement, name vchar);
sqlite3函数接口
int sqlite3_open(
 const char filename, / Database filename (UTF-8) */
 sqlite3 *ppDb / OUT: SQLite db handle */
 ); 
  功能：打开数据库
参数：filename 数据库名称
 ppdb 数据库句柄
返回值：成功为0 SQLITE_OK ,出错 错误码
 int sqlite3_close(sqlite3* db);
功能：关闭数据库
参数：
返回值：成功为0 SQLITE_OK ,出错 错误码
 const char sqlite3_errmsg(sqlite3db);
功能：得到错误信息的描述
int sqlite3_exec(
 sqlite3* db, /* An open database /
 const char sql, / SQL to be evaluated /
 int (callback)(void arg,int,char,char**), /* Callback function /
 void * arg, / 1st argument to callback */
 char *errmsg / Error msg written here */
 );
 
功能：执行一条sql语句
参数：db 数据库句柄
 sql sql语句
 callback 回调函数，只有在查询时，才传参
 arg 为回调函数传递参数
 errmsg 错误消息
返回值：成功 SQLITE_OK
查询回调函数：
 int (callback)(void arg,int ncolumns ,char** f_value,char** f_name), /* Callback function */
功能：查询语句执行之后，会回调此函数
参数：arg 接收sqlite3_exec 传递来的参数
 ncolumns 列数
 f_value　列的值得地址
 f_name 列的名称
返回值：0，
int sqlite3_get_table(
 sqlite3 db, / An open database */
 const char zSql, / SQL to be evaluated */
 char **pazResult, / Results of the query */
 int pnRow, / Number of result rows written here */
 int pnColumn, / Number of result columns written here */
 char *pzErrmsg / Error msg written here */
 );
 void sqlite3_free_table(char **result);
 查询
学生管理系统案例代码如下：#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sqlite3.h>

#define  DATABASE  "student.db"
#define  N  128

int do_insert(sqlite3 *db)
{
	int id;
	char name[32] = {};
	char sex;
	int score;
	char sql[N] = {};
	char *errmsg;

	printf("Input id:");
	scanf("%d", &id);

	printf("Input name:");
	scanf("%s", name);
	getchar();

	printf("Input sex:");
	scanf("%c", &sex);

	printf("Input score:");
	scanf("%d", &score);

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

	if(sqlite3_exec(db, sql, NULL, NULL, &errmsg) != SQLITE_OK)
	{
		printf("%s\n", errmsg);
	}
	else
	{
		printf("Insert done.\n");
	}

	return 0;
}
int do_delete(sqlite3 *db)
{
	int id;
	char sql[N] = {};
	char *errmsg;

	printf("Input id:");
	scanf("%d", &id);

	sprintf(sql, "delete from stu where id = %d", 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(sqlite3 *db)
{
	int id;
	char sql[N] = {};
	char name[32] = "zhangsan";
	char *errmsg;

	printf("Input id:");
	scanf("%d", &id);

	sprintf(sql, "update stu set name='%s' where id=%d", name,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]);
	}

	printf("++++++++++++++++++++++");
	putchar(10);

	return 0;
}

int do_query(sqlite3 *db)
{
	char *errmsg;
	char sql[N] = "select count(*) from stu where name='zhangsan';";

	if(sqlite3_exec(db, sql, callback,NULL , &errmsg) != SQLITE_OK)
	{
		printf("%s", errmsg);
	}
	else
	{
		printf("select done.\n");
	}
}

int do_query1(sqlite3 *db)
{
	char *errmsg;
	char ** resultp;
	int nrow;
	int ncolumn;

	if(sqlite3_get_table(db, "select * from stu", &resultp, &nrow, &ncolumn, &errmsg) != SQLITE_OK)
	{
		printf("%s\n", errmsg);
		return -1;
	}
	else
	{
		printf("query done.\n");
	}

	int i = 0;
	int j = 0;
	int index = ncolumn;

	for(j = 0; j < ncolumn; j++)
	{
		printf("%-10s ", resultp[j]);
	}
	putchar(10);

	for(i = 0; i < nrow; i++)
	{
		for(j = 0; j < ncolumn; j++)
		{
			printf("%-10s ", resultp[index++]);
		}
		putchar(10);
	}

return 0;
}

int main(int argc, const char *argv[])
{
	sqlite3 *db;
	char *errmsg;
	int n;
	
	if(sqlite3_open(DATABASE, &db) != SQLITE_OK)
	{
		printf("%s\n", sqlite3_errmsg(db));
		return -1;
	}
	else
	{
		printf("open DATABASE success.\n");
	}

	if(sqlite3_exec(db, "create table if not exists stu(id int, name char , sex char , score int);",
				NULL, NULL, &errmsg) != SQLITE_OK)
	{
		printf("%s\n", errmsg);
	}
	else
	{
		printf("Create or open table success.\n");
	}

	while(1)
	{
		printf("********************************************\n");
		printf("1: insert  2:query  3:delete 4:update 5:quit\n");
		printf("********************************************\n");
		printf("Please select:");
		scanf("%d", &n);

		switch(n)
		{
			case 1:
				do_insert(db);
				break;
			case 2:
				do_query(db);
			//	do_query1(db);
				break;
			case 3:
				do_delete(db);
				break;
			case 4:
				do_update(db);
				break;
			case 5:
				printf("main exit.\n");
				sqlite3_close(db);
				exit(0);
				break;
			default :
				printf("Invalid data n.\n");
		}

	}




	return 0;
}
 注：query1中的话为啥index++，因为API里面要把表头去掉，表结构如下：
 

                