【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