Linux中数据库sqlite3的基本命令的使用

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：
c 复制代码
```
sudo dpkg -i  *.deb
```
检查是否安装成功
c 复制代码
```
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：

c 复制代码

#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：