公司最近在做离线缓存的东西，用的是sqlite数据库保存的。使用第三方类库FMDataBase对数据库进行相关操作，这是我写的一个小demo，废话不说，先上效果图：

在操作数据库的时候遇到了一点小问题，sqlite里面string类型就用text来存储，int型用integer,float用real,

需要注意的是：插入数据的时候如果string类型直接插入，但是要是float或者是integer类型就需要将插入值转化成NSNumber数据类型如下：[NSNumber numberWithInt:24]

在调试数据库操作的时候最好在模拟器上进行，然后打印出数据库路径，然后查看数据库里面的数据，是否存在，这里推荐一个查看sqlite数据库的软件，很小，功能不算强大但是也勉强够用了。（不要积分）

http://download.csdn.net/detail/zyzxrj/8203551

还需要注意一点，做数据库增删的时候不可查看数据库，这时候数据库会被锁住，导致插入或者删除失败。但是查询操作可以。

可参考下面语句

    NSString *createMessageTable = @"create table if not exists message(messageNo integer primary key,failldReason text,contract text,contractPhone text,isRead integer, orderStatus integer, messageType integer, acceptMessageTime text,appointedTime text,orderDate text,startStation text,arrivalStation text,transportLocation text,tradeNo text) ";

这个界面我为了省时间直接xib拖得，相信有一定ios开发基础的人都可以用代码写出来，我也不废话了，主要说一些数据库操作的问题：

DataBaseViewController.h:

#import <UIKit/UIKit.h>

@interface DataBaseViewController : UIViewController
@property (weak, nonatomic) IBOutlet UITextField *nameTextField;
@property (weak, nonatomic) IBOutlet UITextField *sexTextField;
@property (weak, nonatomic) IBOutlet UITextField *ageTextField;

- (IBAction)save:(id)sender;
- (IBAction)query:(id)sender;
- (IBAction)queryByCondition:(id)sender;
- (IBAction)update:(id)sender;
- (IBAction)deleteByCondition:(id)sender;

@end

//
//  DataBaseViewController.m
//  Location
//
//  Created by admin on 14-11-17.
//  Copyright (c) 2014年 admin. All rights reserved.
//

#import "DataBaseViewController.h"
#import "FMDatabase.h"
#import "FMDatabaseQueue.h"
#define IOS7_OR_LATER   ([[[UIDevice currentDevice] systemVersion]floatValue] >= 7.0)
@interface DataBaseViewController ()

@end

@implementation DataBaseViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    //控制器，点击空白地方，隐藏键盘
    CGRect cgrect = self.view.frame;
    if (!IOS7_OR_LATER) {
        cgrect.origin.y -= 20;
    }
    UIControl *clickControl = [[UIControl alloc] init];
    clickControl.frame = cgrect;
    [clickControl addTarget:self action:@selector(hideKeyboard) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:clickControl];
    [self.view sendSubviewToBack:clickControl];
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}
//隐藏软键盘
- (void)hideKeyboard
{
    [_nameTextField resignFirstResponder];
    [_ageTextField resignFirstResponder];
    [_sexTextField resignFirstResponder];
}
- (IBAction)save:(id)sender {
    //获取Document文件夹下的数据库文件，没有则创建
    NSString *docPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
    NSString *dbPath = [docPath stringByAppendingPathComponent:@"user.db"];
    NSLog(@"%@",dbPath);
    //获取数据库并打开
    FMDatabase *dataBase = [FMDatabase databaseWithPath:dbPath];
    if (![dataBase open]) {
        NSLog(@"打开数据库失败");
        return ;
    }
    //创建表（FMDB中只有update和query操作，出了查询其他都是update操作）
    [dataBase executeUpdate:@"create table if not exists user(name text,gender text,age integer) "];
    //插入数据
    BOOL inser = [dataBase executeUpdate:@"insert into user values(?,?,?)",_nameTextField.text,_sexTextField.text,_ageTextField.text];
    if (inser) {
        UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"提示" message:@"信息保存成功" delegate:self cancelButtonTitle:nil otherButtonTitles:@"确定", nil];
        [alert show];
    }
    [dataBase close];
}
//查询全部
- (IBAction)query:(id)sender {
    NSString *docPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
    NSString *dbPath = [docPath stringByAppendingPathComponent:@"user.db"];
    
    FMDatabase *dataBase = [FMDatabase databaseWithPath:dbPath];
    if (![dataBase open]) {
        NSLog(@"打开数据库失败");
        return ;
    }
    FMResultSet *resultSet = [dataBase executeQuery:@"select * from user"];
    while ([resultSet next]) {
        NSString *name = [resultSet stringForColumn:@"name"];
        NSString *genter = [resultSet stringForColumn:@"gender"];
        int age = [resultSet intForColumn:@"age"];
        NSLog(@"Name:%@,Gender:%@,Age:%d",name,genter,age);
    }
    
    [dataBase close];
}
//条件查询
- (IBAction)queryByCondition:(id)sender {
    NSString *docPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
    NSString *dbPath = [docPath stringByAppendingPathComponent:@"user.db"];
    FMDatabase *dataBase = [FMDatabase databaseWithPath:dbPath];
    if (![dataBase open]) {
        return ;
    }
//    FMResultSet *resultSet = [dataBase executeQuery:@"select *from user where name = ?",@"ZY"];
    FMResultSet *resultSet = [dataBase executeQueryWithFormat:@"select * from user where name = %@",@"zy"];
    while ([resultSet next]) {
        NSString *name = [resultSet stringForColumnIndex:0];
        NSString *gender = [resultSet stringForColumn:@"gender"];
        int age = [resultSet intForColumn:@"age"];
        NSLog(@"Name:%@,Gender:%@,Age:%d",name,gender,age);
    }
    [dataBase close];
}

- (IBAction)update:(id)sender {
    NSString *docPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
    NSString *dbPath = [docPath stringByAppendingPathComponent:@"user.db"];
    FMDatabase *dataBase = [FMDatabase databaseWithPath:dbPath];
    if (![dataBase open]) {
        return ;
    }
    //参数必须是NSObject的子类，int,double,bool这种基本类型，需要封装成对应的包装类才可以
    BOOL update = [dataBase executeUpdate:@"update user set age = ? where name = ?",[NSNumber numberWithInt:24],@"ZY"];
    if (update) {
        UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"提示" message:@"信息更新成功" delegate:self cancelButtonTitle:nil otherButtonTitles:@"确定", nil];
        [alert show];
    }
    [dataBase close];
}

- (IBAction)deleteByCondition:(id)sender
{
    NSString *docPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
    NSString *dbPath = [docPath stringByAppendingPathComponent:@"user.db"];
    FMDatabase *dataBase = [FMDatabase databaseWithPath:dbPath];
    if (![dataBase open]) {
        return ;
    }
    BOOL delete = [dataBase executeUpdateWithFormat:@"delete from user where name = %@",@"zy"];
    if (delete) {
        UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"提示" message:@"信息删除成功" delegate:self cancelButtonTitle:nil otherButtonTitles:@"确定", nil];
        [alert show];
    }
    [dataBase close];
}

@end

http://download.csdn.net/detail/zyzxrj/8203583

大家要是有不解之处可以参考代码

IOS 操作数据库（FMDB）