创建一个数据库（包括int 类型的id，string 类型的name），并对其进行增删改查

实现步骤：

1.创建一个SingleViewApplication应用。

    sqlite3数据库可以采用MesaSQLite可视化工具

2.添加sqlite3支持的库文件，libsqlite3.dylib

3.创建viewController控制器，布局好界面

ViewController.h:

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController
- (IBAction)addClick:(id)sender;
- (IBAction)deleteClick:(id)sender;
- (IBAction)updateClick:(id)sender;
- (IBAction)selectClick:(id)sender;
@property (retain, nonatomic) IBOutlet UITextField *idText;
@property (retain, nonatomic) IBOutlet UITextField *nameText;
- (IBAction)viewClick:(id)sender;
@property (retain, nonatomic) IBOutlet UISearchBar *txtSearchBar;

@end

ViewController.m:

#import "ViewController.h"
#import <sqlite3.h>
#define kFilename @"Homeworkdb.rdb"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];

}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

-(NSString *)dataFilePath
{
    NSArray *path = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString * document = [path objectAtIndex:0];
    return [document stringByAppendingPathComponent:kFilename];
}

//增加
- (IBAction)addClick:(id)sender {
    //创建
    sqlite3 * database;
    if(sqlite3_open([[self dataFilePath] UTF8String], &database)!=SQLITE_OK)
    {
        sqlite3_close(database);
        NSAssert(0, @"Failed to open database");
    }

    NSString * creataSQL = @"CREATE TABLE IF NOT EXISTS FIELDS" "(id INTEGER PRIMARY KEY,name TEXT);";
    char * errorMsg;
    if(sqlite3_exec(database, [creataSQL UTF8String], NULL, NULL, &errorMsg)!=SQLITE_OK)
    {
        sqlite3_close(database);
        NSAssert(0, @"Error creating table:%s",errorMsg);
    }

    char * update = "insert or replace into FIELDS (id, name)" "values (?,?);";
    sqlite3_stmt * stmt;
    if(sqlite3_prepare_v2(database, update, -1, &stmt, nil) == SQLITE_OK)
    {
        sqlite3_bind_int(stmt, 1, [self.idText.text intValue]);   //1表示第一个问号
        sqlite3_bind_text(stmt, 2, [self.nameText.text UTF8String], -1, NULL);//2表示第二个问号
    }
    if(sqlite3_step(stmt)!=SQLITE_DONE)
    {
        NSAssert(0, @"Error updating table:%s",errorMsg);
    }
    sqlite3_finalize(stmt);      //这句话不能漏

    sqlite3_close(database);   //关闭数据库

    UIAlertView *a = [[UIAlertView alloc] initWithTitle:@"友情提示" message:@"添加成功" delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];
    [a show];
}

//删除
- (IBAction)deleteClick:(id)sender {
    sqlite3 * database;
    if(sqlite3_open([[self dataFilePath] UTF8String], &database)!=SQLITE_OK)
    {
        sqlite3_close(database);
        NSAssert(0, @"Failed to open database");
    }

    NSString * creataSQL = @"CREATE TABLE IF NOT EXISTS FIELDS" "(id INTEGER PRIMARY KEY,name TEXT);";
    char * errorMsg;
    if(sqlite3_exec(database, [creataSQL UTF8String], NULL, NULL, &errorMsg)!=SQLITE_OK)
    {
        sqlite3_close(database);
        NSAssert(0, @"Error creating table:%s",errorMsg);
    }

        char * del = "delete from FIELDS where id = ?;";
        sqlite3_stmt * stmt;
        if(sqlite3_prepare_v2(database, del, -1, &stmt, nil) == SQLITE_OK)
        {
            sqlite3_bind_int(stmt, 1, [self.idText.text intValue]);   //1表示第一个问号
        }
        if(sqlite3_step(stmt)!=SQLITE_DONE)
        {
            NSAssert(0, @"Error delete table:%s",errorMsg);
        }
        sqlite3_finalize(stmt);      

    sqlite3_close(database);

    UIAlertView *a = [[UIAlertView alloc] initWithTitle:@"友情提示" message:@"删除成功" delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];
    [a show];
}

//修改
- (IBAction)updateClick:(id)sender {
    sqlite3 * database;
    if(sqlite3_open([[self dataFilePath] UTF8String], &database)!=SQLITE_OK)
    {
        sqlite3_close(database);
        NSAssert(0, @"Failed to open database");
    }

    NSString * creataSQL = @"CREATE TABLE IF NOT EXISTS FIELDS" "(id INTEGER PRIMARY KEY,name TEXT);";
    char * errorMsg;
    if(sqlite3_exec(database, [creataSQL UTF8String], NULL, NULL, &errorMsg)!=SQLITE_OK)
    {
        sqlite3_close(database);
        NSAssert(0, @"Error creating table:%s",errorMsg);
    }

    char * update = "update FIELDS set id = ?,name = ? where id = ?";
    sqlite3_stmt * stmt;
    if(sqlite3_prepare_v2(database, update, -1, &stmt, nil) == SQLITE_OK)
    {
        sqlite3_bind_int(stmt, 1, [self.idText.text intValue]);   //1表示第一个问号
        sqlite3_bind_text(stmt, 2, [self.nameText.text UTF8String], -1, NULL);//2表示第二个问号
        sqlite3_bind_int(stmt, 3, [self.idText.text intValue]);
    }
    if(sqlite3_step(stmt)!=SQLITE_DONE)
    {
        NSAssert(0, @"Error updating table:%s",errorMsg);
    }
    sqlite3_finalize(stmt);      //这句话不能漏

    sqlite3_close(database);   //关闭数据库

    UIAlertView *a = [[UIAlertView alloc] initWithTitle:@"友情提示" message:@"修改成功" delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];
    [a show];
}

//查询
- (IBAction)selectClick:(id)sender {
    //创建数据库
    sqlite3 * database;
    if(sqlite3_open([[self dataFilePath] UTF8String], &database)!=SQLITE_OK)
    {
        sqlite3_close(database);
        NSAssert(0, @"Failed to open database");
    }

    NSString * creataSQL = @"CREATE TABLE IF NOT EXISTS FIELDS" "(id INTEGER PRIMARY KEY,name TEXT);";
    char * errorMsg;
    if(sqlite3_exec(database, [creataSQL UTF8String], NULL, NULL, &errorMsg)!=SQLITE_OK)
    {
        sqlite3_close(database);
        NSAssert(0, @"Error creating table:%s",errorMsg);
    }

    NSString * query = @"select * from FIELDS where id = ?";
    sqlite3_stmt * statement;
    if(sqlite3_prepare_v2(database, [query UTF8String], -1, &statement, nil) == SQLITE_OK)
    {
        sqlite3_bind_int(statement, 1, [self.txtSearchBar.text intValue]);
        //sqlite3_bind_text(statement, 2, [self.nameText.text UTF8String], -1, NULL);
        while(sqlite3_step(statement) == SQLITE_ROW)
        {
            int id = sqlite3_column_int(statement, 0);    //0表示第1列
            char * name = (char *)sqlite3_column_text(statement, 1);  //1表示第2列

            NSString * sid = [[NSString alloc] initWithFormat:@"%d",id];
            NSString * sname = [[NSString alloc] initWithUTF8String:name];
            self.nameText.text = sname;
            self.idText.text = sid;
            UIAlertView *a = [[UIAlertView alloc] initWithTitle:@"友情提示" message:@"查询成功" delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];
            [a show];
        }

        sqlite3_finalize(statement);
    }
    else
    {
        NSLog(@"error");
    }

    sqlite3_close(database);
}

- (void)dealloc {
    [_idText release];
    [_nameText release];
    [_txtSearchBar release];
    [super dealloc];
}
- (IBAction)viewClick:(id)sender {
    [self.idText resignFirstResponder];
    [self.nameText resignFirstResponder];
}
@end