关于SQLite的基本使用

//SQLite的基本使用-Prefix.pch

1.

//

// Prefix header

// The contents of this file are implicitly included at the beginning of every source file.

//

#ifdef __OBJC__

#import <Foundation/Foundation.h>

#endif

// Prefix header

//

// The contents of this file are implicitly included at the beginning of every source file.

//

#import <Availability.h>

#ifndef __IPHONE_5_0

#warning "This project uses features only available in iOS SDK 5.0 and later."

#endif

#ifdef __OBJC__

#import <UIKit/UIKit.h>

#import <Foundation/Foundation.h>

#endif

#import <Foundation/Foundation.h>

int main(int argc,const char * argv[])

{

@autoreleasepool {

NSMutableString *sql = [NSMutableString string];

NSArray *names = @[@"jack", @"rose",@"jim", @"jake"];

for (int i = 0; i<100; i++) {

int index = arc4random()%names.count;

NSString *namePre = names[index];

NSString *name = [NSString stringWithFormat:@"%@-%d",namePre,arc4random()%100];

int age = arc4random() % 100;

double score = arc4random() % 100;

[sql appendFormat:@"insert into t_student (name,age,score) values('%@',%d,%f);n",name,score];

}

///Users/mc/Desktop/素材images

///Users/aplle/Desktop/student.sql

[sql writeToFile:@"Users/mc/Desktop/student.sql" atomically:YES encoding:NSUTF8StringEncoding error:nil];

}

return 0;

}

*****************************

#import <Foundation/Foundation.h>

int main(int argc,const char * argv[])

{

@autoreleasepool {

NSArray *names = @[@"西门抽血",@"西门抽筋",@"西门抽风",@"西门吹雪"];

NSMutableString *sql = [NSMutableString string];

for (int i = 0; i<200; i++) {

int ID = i + 1;

int age = arc4random_uniform(20) + 20;

NSString *name = names[arc4random_uniform(names.count)];

name = [name stringByAppendingFormat:@"-%d",arc4random_uniform(100)];

[sql appendFormat:@"insert into t_student (id,age) values (%d,'%@',%d);n",ID,age];

}

[sql writeToFile:@"/Users/apple/Desktop/students.sql" atomically:YES encoding:NSUTF8StringEncoding error:nil];

NSLog(@"n%@",sql);

}

return 0;

}

插入数据：更改删除查询--->>>>>>>>>

#import<sqlite3.h>

@interfaceIWViewController()

{

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

@implementationIWViewController

- (void)viewDidLoad

{

[superviewDidLoad];

// 0.获得沙盒中的数据库文件名

NSString*filename = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMaskYES)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）

intresult =sqlite3_open(filename.UTF8String,&_db);

if(result ==SQLITE_OK) {

NSLog(@"成功打开数据库");

// 2.创表

constchar*sql ="create table if not exists t_student (id integer primary key autoincrement,name text,age integer);";

char*errorMesg =NULL;

sqlite3_exec(_db,sql,NULL,&errorMesg);

SQLITE_OK) {

NSLog(@"成功创建t_student表");

}else{

创建t_student表失败:%s",errorMesg);

}

}else{

打开数据库失败");

}

}

- (IBAction)insert

{

for(inti =0; i<30; i++) {

NSString*name = [NSStringstringWithFormat:@"Jack-%d",arc4random()%100];

intage =100;

*sql = [stringWithFormat:@"insert into t_student (name,age) values('%@',%d);"

SQLITE_OK) {

成功添加数据");

}添加数据失败 }

}

}

- (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';

*/

// 1.定义sql语句

*sql ="select id,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

sqlite3_prepare_v2(1,&stmt,162)">NULL);

查询语句是合法的");

//设置占位符的内容

sqlite3_bind_text(stmt,"jack",162)">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

intsid =sqlite3_column_int(stmt,216)">0);

//获得第1列的name

constunsignedchar*sname =sqlite3_column_text(stmt,216)">1);

2age

intsage =2);

@"%d %s %d",sid,sname,sage);

}

}查询语句非合法");

}

}

@end

2.*************************

#import "ViewController.h"

#import <sqlite3.h>

@interface ViewController ()

- (IBAction)insert;

- (IBAction)update;

- (IBAction)delete;

- (IBAction)select;

// db就是数据库的象征，如果要进行CRUD，得操作db这个实例

@property (nonatomic,assign) sqlite3 *db;

@end

@implementation HMViewController

- (void)viewDidLoad

{

[super viewDidLoad];

// 获得数据库文件的路径

NSString *doc = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask,YES) lastObject];

NSString *filename = [doc stringByAppendingPathComponent:@"students.sqlite"];

// 将OC字符串 转成 C语言字符串

const char *cfilename = filename.UTF8String;

// 1.打开数据库（如果数据库文件不存在，sqlite3_open函数会自动创建数据库文件）

int result = sqlite3_open(cfilename,&_db);

if (result == SQLITE_OK) { // 打开成功

NSLog(@"成功打开数据库");

// 2. const char *sql = "CREATE TABLE IF NOT EXISTS t_student (id integer PRIMARY KEY AUTOINCREMENT,name text NOT NULL,age integer NOT NULL);";

char *erroMsg = NULL;

result = sqlite3_exec(self.db,NULL,&erroMsg);

if (result == SQLITE_OK) {

NSLog(@"成功创表");

} else {

// printf("创表失败--%s--%s-%d",erroMsg,__FILE__,__LINE__);

NSLog(@"创表失败--%s--%@-%d",[NSString stringWithUTF8String:__FILE__],__LINE__);

}

} else {

NSLog(@"打开数据库失败");

}

}

- (IBAction)insert {

for (int i = 0; i<20; i++) {

// 1.拼接SQL语句

NSString *name = [NSString stringWithFormat:@"Jack-%d",arc4random_uniform(100)];

int age = arc4random_uniform(20) + 30;

NSString *sql = [NSString stringWithFormat:@"INSERT INTO t_student (name,age) VALUES ('%@',%d);",age];

// 2.执行SQL语句

char *erroMsg = NULL;

sqlite3_exec(self.db,sql.UTF8String,&erroMsg);

if (erroMsg) {

NSLog(@"插入数据失败--%s",erroMsg);

} else {

NSLog(@"成功插入数据");

}

}

}

- (IBAction)update {

}

- (IBAction)delete {

}

- (IBAction)select {

const char *sql = "SELECT id,age FROM t_student WHERE age <= 30;";

// 进行查询前的准备工作

// -1 代表系统会自动计算SQL语句的长度

// sqlite3_stmt：用来取数据

sqlite3_stmt *stmt = NULL;

if (sqlite3_prepare_v2(self.db,-1,NULL) == SQLITE_OK) { // SQL语句没有问题

NSLog(@"查询语句没有问题");

// 每调一次sqlite3_step函数，stmt就会指向下一条记录

while (sqlite3_step(stmt) == SQLITE_ROW) { // 找到一条记录

// 取出数据

// 取出第0列字段的值（int类型的值）

int ID = sqlite3_column_int(stmt,0);

// 取出第1列字段的值（tex类型的值）

const unsigned char *name = sqlite3_column_text(stmt,1);

// 取出第2列字段的值（int类型的值）

int age = sqlite3_column_int(stmt,2);

NSLog(@"%d %s %d",age);

}

} else {

NSLog(@"查询语句有问题");

}

}

@end

（编辑：李大同）

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