【转】 iOS学习之sqlite的创建数据库,表,插入查看数据

原文：  http://blog.csdn.net/totogo2010/article/details/7702207

iOS sqlite数据库操作。步骤是：

先加入sqlite开发库libsqlite3.dylib，

新建或打开数据库，

创建数据表，

插入数据，

查询数据并打印

1、新建项目sqliteDemo,添加使用sqlite的库libsqlite3.dylib

2、sqlite 的方法

sqlite3          *db, 数据库句柄，跟文件句柄FILE很类似

sqlite3_stmt      *stmt, 这个相当于ODBC的Command对象，用于保存编译好的SQL语句
sqlite3_open(),   打开数据库，没有数据库时创建。
sqlite3_exec(),   执行非查询的sql语句
Sqlite3_step(), 在调用sqlite3_prepare后，使用这个函数在记录集中移动。
Sqlite3_close(), 关闭数据库文件
还有一系列的函数，用于从记录集字段中获取数据，如
sqlite3_column_text(), 取text类型的数据。
sqlite3_column_blob（），取blob类型的数据
sqlite3_column_int(), 取int类型的数据

3、获取沙盒目录，并创建或打开数据库。

viewController.h头文件添加一个成员变量，并包含头文件sqlite3.h

#import <UIKit/UIKit.h>
#import <sqlite3.h>


@interface ViewController : UIViewController
{
    sqlite3 *db;
}
@end

在.m文件 定义宏，方面后面使用

#define DBNAME    @"personinfo.sqlite"
#define NAME      @"name"
#define AGE       @"age"
#define ADDRESS   @"address"
#define TABLENAME @"PERSONINFO"

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
 NSString *documents = [paths objectAtIndex:0];
 NSString *database_path = [documents stringByAppendingPathComponent:DBNAME];

 if (sqlite3_open([database_path UTF8String], &db) != SQLITE_OK) {
     sqlite3_close(db);
     NSLog(@"数据库打开失败");
 }

sqlite3_open，如果数据不存在，则创建。运行。这是在沙盒目录下能看到数据库文件（如何打开模拟器沙盒目录请参考：iOS学习之iOS沙盒(sandbox)机制和文件操作(一)）

4、创建数据表

创建一个独立的执行sql语句的方法，传入sql语句，就执行sql语句

-(void)execSql:(NSString *)sql
{
    char *err;
    if (sqlite3_exec(db, [sql UTF8String], NULL, NULL, &err) != SQLITE_OK) {
        sqlite3_close(db);
        NSLog(@"数据库操作数据失败!");
    }
}

创建数据表PERSONINFO的语句

NSString *sqlCreateTable = @"CREATE TABLE IF NOT EXISTS PERSONINFO (ID INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT, age INTEGER, address TEXT)";
    [self execSql:sqlCreateTable];

运行程序，数据表创建了。怎么知道数据表创建了呢？我们用火狐的Sqlite Manager插件工具打开数据库文件看看。可以在火狐浏览器里安装这个插件。打开

四个字段都出现是表中了。

5、插入数据：

NSString *sql1 = [NSString stringWithFormat:
                     @"INSERT INTO '%@' ('%@', '%@', '%@') VALUES ('%@', '%@', '%@')",
                     TABLENAME, NAME, AGE, ADDRESS, @"张三", @"23", @"西城区"];

    NSString *sql2 = [NSString stringWithFormat:
                      @"INSERT INTO '%@' ('%@', '%@', '%@') VALUES ('%@', '%@', '%@')",
                      TABLENAME, NAME, AGE, ADDRESS, @"老六", @"20", @"东城区"];
    [self execSql:sql1];
    [self execSql:sql2];

运行程序，插入两条数据，用火狐的sqlite工具查看

6、查询数据库并打印数据

NSString *sqlQuery = @"SELECT * FROM PERSONINFO";
   sqlite3_stmt * statement;

   if (sqlite3_prepare_v2(db, [sqlQuery UTF8String], -1, &statement, nil) == SQLITE_OK) {
       while (sqlite3_step(statement) == SQLITE_ROW) {
           char *name = (char*)sqlite3_column_text(statement, 1);
           NSString *nsNameStr = [[NSString alloc]initWithUTF8String:name];

           int age = sqlite3_column_int(statement, 2);

           char *address = (char*)sqlite3_column_text(statement, 3);
           NSString *nsAddressStr = [[NSString alloc]initWithUTF8String:address];

           NSLog(@"name:%@  age:%d  address:%@",nsNameStr,age, nsAddressStr);
       }
   }
   sqlite3_close(db);

打印结果：

2012-06-29 13:25:32.205 sqlitDemo[3587:f803] name:张三  age:23  address:西城区
2012-06-29 13:25:32.206 sqlitDemo[3587:f803] name:老六  age:20  address:东城区

最后关闭数据库。

附： 可以把数据库操作封装成一个类

创建一个类， 命名为DBManager

更新DBManager.h,如下所示

#import <Foundation/Foundation.h>
#import <sqlite3.h>

@interface DBManager : NSObject
{
    NSString *databasePath;
}

+(DBManager*)getSharedInstance;
-(BOOL)createDB;
-(BOOL) saveData:(NSString*)registerNumber name:(NSString*)name 
  department:(NSString*)department year:(NSString*)year;
-(NSArray*) findByRegisterNumber:(NSString*)registerNumber;

@end

7、更新DBManager.m,如下所示

#import "DBManager.h"
static DBManager *sharedInstance = nil;
static sqlite3 *database = nil;
static sqlite3_stmt *statement = nil;

@implementation DBManager

+(DBManager*)getSharedInstance{
    if (!sharedInstance) {
        sharedInstance = [[super allocWithZone:NULL]init];
        [sharedInstance createDB];
    }
    return sharedInstance;
}

-(BOOL)createDB{
    NSString *docsDir;
    NSArray *dirPaths;    
    // Get the documents directory
    dirPaths = NSSearchPathForDirectoriesInDomains
    (NSDocumentDirectory, NSUserDomainMask, YES);    
    docsDir = dirPaths[0];
    // Build the path to the database file
    databasePath = [[NSString alloc] initWithString: 
    [docsDir stringByAppendingPathComponent: @"student.db"]];
    BOOL isSuccess = YES;
    NSFileManager *filemgr = [NSFileManager defaultManager];    
    if ([filemgr fileExistsAtPath: databasePath ] == NO)
    {
        const char *dbpath = [databasePath UTF8String];        
        if (sqlite3_open(dbpath, &database) == SQLITE_OK)
        {
            char *errMsg;
            const char *sql_stmt =
            "create table if not exists studentsDetail (regno integer 
            primary key, name text, department text, year text)";            
            if (sqlite3_exec(database, sql_stmt, NULL, NULL, &errMsg) 
               != SQLITE_OK)
            {
                isSuccess = NO;
                NSLog(@"Failed to create table");
            }
            sqlite3_close(database);
            return  isSuccess;
        }
        else {
            isSuccess = NO;
            NSLog(@"Failed to open/create database");
        }
    }    
    return isSuccess;
}

- (BOOL) saveData:(NSString*)registerNumber name:(NSString*)name 
  department:(NSString*)department year:(NSString*)year;
{
    const char *dbpath = [databasePath UTF8String];    
    if (sqlite3_open(dbpath, &database) == SQLITE_OK)
    {        
        NSString *insertSQL = [NSString stringWithFormat:@"insert into
        studentsDetail (regno,name, department, year) values
        ("%d","%@", "%@", "%@")",[registerNumber integerValue],
        name, department, year];        
        const char *insert_stmt = [insertSQL UTF8String];
        sqlite3_prepare_v2(database, insert_stmt,-1, &statement, NULL);
        if (sqlite3_step(statement) == SQLITE_DONE)
        {
            return YES;
        } 
        else {
            return NO;
        }
        sqlite3_reset(statement);
    }
    return NO;
}

- (NSArray*) findByRegisterNumber:(NSString*)registerNumber
{
    const char *dbpath = [databasePath UTF8String];    
    if (sqlite3_open(dbpath, &database) == SQLITE_OK)
    {
        NSString *querySQL = [NSString stringWithFormat:
        @"select name, department, year from studentsDetail where 
        regno="%@"",registerNumber];        
        const char *query_stmt = [querySQL UTF8String];
        NSMutableArray *resultArray = [[NSMutableArray alloc]init];
        if (sqlite3_prepare_v2(database,
           query_stmt, -1, &statement, NULL) == SQLITE_OK)
        {
            if (sqlite3_step(statement) == SQLITE_ROW)
            {                
                NSString *name = [[NSString alloc] initWithUTF8String:
                 (const char *) sqlite3_column_text(statement, 0)];
                [resultArray addObject:name];
                NSString *department = [[NSString alloc] initWithUTF8String:
                (const char *) sqlite3_column_text(statement, 1)];
                [resultArray addObject:department];
                NSString *year = [[NSString alloc]initWithUTF8String:
                (const char *) sqlite3_column_text(statement, 2)];
                [resultArray addObject:year];
                return resultArray;
            }
            else{
                NSLog(@"Not found");
                return nil;
            }
            sqlite3_reset(statement);
        }
    }
    return nil;
}

8、如图所示，更新ViewController.xib文件

9、为上述文本字段创建IBOutlets

10、为上述按钮创建IBAction

11、如下所示，更新ViewController.h

#import <UIKit/UIKit.h>
#import "DBManager.h"

@interface ViewController : UIViewController<UITextFieldDelegate>
{
    IBOutlet UITextField *regNoTextField;
    IBOutlet UITextField *nameTextField;
    IBOutlet UITextField *departmentTextField;
    IBOutlet UITextField *yearTextField;
    IBOutlet UITextField *findByRegisterNumberTextField;
    IBOutlet UIScrollView *myScrollView;
}

-(IBAction)saveData:(id)sender;
-(IBAction)findData:(id)sender;

@end

12、更新ViewController.m,如下所示

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

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

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view from its nib.
}

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

-(IBAction)saveData:(id)sender{
    BOOL success = NO;
    NSString *alertString = @"Data Insertion failed";
    if (regNoTextField.text.length>0 &&nameTextField.text.length>0 &&
    departmentTextField.text.length>0 &&yearTextField.text.length>0 )
    {
        success = [[DBManager getSharedInstance]saveData:
        regNoTextField.text name:nameTextField.text department:
        departmentTextField.text year:yearTextField.text];
    }
    else{
        alertString = @"Enter all fields";
    }     
    if (success == NO) {
        UIAlertView *alert = [[UIAlertView alloc]initWithTitle:
        alertString message:nil
        delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
        [alert show];
    }
}

-(IBAction)findData:(id)sender{
    NSArray *data = [[DBManager getSharedInstance]findByRegisterNumber:
    findByRegisterNumberTextField.text];
    if (data == nil) {
        UIAlertView *alert = [[UIAlertView alloc]initWithTitle:
        @"Data not found" message:nil delegate:nil cancelButtonTitle:
        @"OK" otherButtonTitles:nil];
        [alert show];
        regNoTextField.text = @"";
        nameTextField.text =@"";
        departmentTextField.text = @"";
        yearTextField.text =@"";
    }
    else{
        regNoTextField.text = findByRegisterNumberTextField.text;
        nameTextField.text =[data objectAtIndex:0];
        departmentTextField.text = [data objectAtIndex:1];
        yearTextField.text =[data objectAtIndex:2];
    }
}

#pragma mark - Text field delegate
-(void)textFieldDidBeginEditing:(UITextField *)textField{
    [myScrollView setFrame:CGRectMake(10, 50, 300, 200)];
    [myScrollView setContentSize:CGSizeMake(300, 350)];
}
-(void)textFieldDidEndEditing:(UITextField *)textField{
    [myScrollView setFrame:CGRectMake(10, 50, 300, 350)];

}
-(BOOL) textFieldShouldReturn:(UITextField *)textField{
    
    [textField resignFirstResponder];
    return YES;
}
@end

输出

现在当我们运行应用程序时，我们就会获得下面的输出，我们可以在其中添加及查找学生的详细信息