iOS - SQLite Database 操作数据库

Sqlite 能被用在ios上做数据处理用，只要你懂得一点sql 就很容易使用sqlite

1：创建一个简单的View based application2：现在你的项目文件，选择targets 并从库中选择libsqlite3.dylib添加到框架中

3：我们创建一个新的文件 File->New->File->选择Objective C class 并点击next

4：类名称取名为DBManager 子类为NSObject

5：选择创建

6：更新DBManager.h文件

#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文件

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#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：更新ViewController.xib如图

9：为上面的text fields创建一个IBOutlets

10：为上面按钮创建一个 IBAction

11：更新 ViewController.h文件

#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文件

#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

最后输出运行结果为：

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