sqlite3 数据库操作

#import "IWViewController.h"
#import <sqlite3.h>

@interface IWViewController ()
{
sqlite3 *_db; // db代表着整个数据库，db是数据库实例
}
- (IBAction)insert;
- (IBAction)update;
- (IBAction)delete;
- (IBAction)query;
@end

@implementation IWViewController

- (void)viewDidLoad
{
[super viewDidLoad];

// 0.获得沙盒中的数据库文件名
NSString *filename = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:@"student.sqlite"];

// 1.创建(打开)数据库（如果数据库文件不存在，会自动创建）
int result = sqlite3_open(filename.UTF8String, &_db);
if (result == SQLITE_OK) {
NSLog(@"成功打开数据库");

// 2.创表
const char *sql = "create table if not exists t_student (id integer primary key autoincrement, name text, age integer);";
char *errorMesg = NULL;
int result = sqlite3_exec(_db, sql, NULL, NULL, &errorMesg);
if (result == SQLITE_OK) {
NSLog(@"成功创建t_student表");
} else {
NSLog(@"创建t_student表失败:%s", errorMesg);
}
} else {
NSLog(@"打开数据库失败");
}
}

- (IBAction)insert
{
for (int i = 0; i<30; i++) {
NSString *name = [NSString stringWithFormat:@"Jack-%d", arc4random()%100];
int age = arc4random()%100;
NSString *sql = [NSString stringWithFormat:@"insert into t_student (name, age) values('%@', %d);", name, age];

char *errorMesg = NULL;
int result = sqlite3_exec(_db, sql.UTF8String, NULL, NULL, &errorMesg);
if (result == SQLITE_OK) {
NSLog(@"成功添加数据");
} else {
NSLog(@"添加数据失败:%s", errorMesg);
}
}
}

- (IBAction)update
{

}

- (IBAction)delete
{

}

- (IBAction)query
{
// SQL注入漏洞

/**
登录功能

1.用户输入账号和密码
* 账号：123' or 1 = 1 or '' = '
* 密码：456654679

2.拿到用户输入的账号和密码去数据库查询（查询有没有这个用户名和密码）
select * from t_user where username = '123' and password = '456';

select * from t_user where username = '123' and password = '456';
*/

// 1.定义sql语句
const char *sql = "select id, name, age from t_student where name = ?;";

// 2.定义一个stmt存放结果集
sqlite3_stmt *stmt = NULL;

// 3.检测SQL语句的合法性
int result = sqlite3_prepare_v2(_db, sql, -1, &stmt, NULL);
if (result == SQLITE_OK) {
NSLog(@"查询语句是合法的");

// 设置占位符的内容
sqlite3_bind_text(stmt, 1, "jack", -1, NULL);

// 4.执行SQL语句，从结果集中取出数据
//        int stepResult = sqlite3_step(stmt);
while (sqlite3_step(stmt) == SQLITE_ROW) { // 真的查询到一行数据
// 获得这行对应的数据

// 获得第0列的id
int sid = sqlite3_column_int(stmt, 0);

// 获得第1列的name
const unsigned char *sname = sqlite3_column_text(stmt, 1);

// 获得第2列的age
int sage = sqlite3_column_int(stmt, 2);

NSLog(@"%d %s %d", sid, sname, sage);
}
} else {
NSLog(@"查询语句非合法");
}
}
@end