sqlite的应用实例

声明：下面的代码是引用别人的：

代码截图：

运行的结果图：

下面是程序中主要的代码：

模型product的代码：

product.h 的文件爱你
#import <Foundation/Foundation.h>

//这个就是模型类，对应这数据库中的属性字段。
@interface Product : NSObject {
    int ID;
    NSString* name;
    NSString* manufacturer;
    NSString* details;
    float price;
    int quantity;
    NSString* countryOfOrigin;
    NSString* image;
}

@property (nonatomic) int ID;
@property (strong,nonatomic) NSString *name;
@property (strong,nonatomic) NSString *manufacturer;
@property (strong,nonatomic) NSString *details;
@property (nonatomic) float price;
@property (nonatomic) int quantity;
@property (strong,nonatomic) NSString *countryOfOrigin;
@property (strong,nonatomic) NSString *image;

@end

product.m文件，尤其这样实现是为了和在字段中的属性名字对应。
#import "Product.h"

@implementation Product

@synthesize ID;
@synthesize name;
@synthesize manufacturer;
@synthesize details;
@synthesize price;
@synthesize quantity;
@synthesize countryOfOrigin;
@synthesize image;

@end

下面是DBAccess类的代码：

DBAccess.h文件。
#import <Foundation/Foundation.h>

// This includes the header for the SQLite library.
#import <sqlite3.h>
#import "Product.h"

//用来获取数据库中的数据，添加到模型中库

@interface DBAccess : NSObject {
    
    
}

//获取的数组方法
- (NSMutableArray*) getAllProducts;
//关闭数据库
- (void) closeDatabase;

//初始化数据库，包括打开数据库
- (void)initializeDatabase;

@end

DBAccess.m文件。
#import "DBAccess.h"

@implementation DBAccess

// Reference to the SQLite database.
sqlite3* database;

//初始化方法，集成NSObject类，启动的时候就会调用这个方法。
-(id) init
{
 if ((self = [super init]))
 {
 [self initializeDatabase];
 }
 return self;
}

// 获取数据库文件、打开、连接
- (void)initializeDatabase {
 
 // Get the database from the application bundle.
 NSString *path = [[NSBundle mainBundle]
 pathForResource:@"catalog"
 ofType:@"db"];
 
 // Open the database.
 if (sqlite3_open([path UTF8String],&database) == SQLITE_OK)
 {
 NSLog(@"Opening Database");
 }
 else
 {
 // Call close to properly clean up
 sqlite3_close(database);
 NSAssert1(0,@"Failed to open database: ‘%s’.",sqlite3_errmsg(database));
 }
}

//关闭数据库
-(void) closeDatabase
{
 // Close the database.
 if (sqlite3_close(database) != SQLITE_OK) {
 NSAssert1(0,@"Error: failed to close database: ‘%s’.",sqlite3_errmsg(database));
 }
}

//获取数据库中product的所有记录存储到数组中
- (NSMutableArray*) getAllProducts
{
 NSLog(@"获取数据");
 // The array of products that we will create
 NSMutableArray *products = [[NSMutableArray alloc] init];

 // The SQL statement that we plan on executing against the database
 const char *sql = "SELECT product.ID,product.Name,
 Manufacturer.name,product.details,product.price,
 product.quantityonhand,country.country,
 product.image FROM Product,Manufacturer,
 Country where manufacturer.manufacturerid=product.manufacturerid 
 and product.countryoforiginid=country.countryid";

 // The SQLite statement object that will hold our result set
 sqlite3_stmt *statement;
 
 // Prepare the statement to compile the SQL query into byte-code
 int sqlResult = sqlite3_prepare_v2(database,sql,-1,&statement,NULL);

 if ( sqlResult== SQLITE_OK) {
 // Step through the results - once for each row.
 //#define SQLITE_ROW sqlite3_step() has another row ready
 while (sqlite3_step(statement) == SQLITE_ROW) {
 // allocate a Product object to add to products array
 Product *product = [[Product alloc] init];
 // The second parameter is the column index (0 based) in
 // the result set.
 char *name = (char *)sqlite3_column_text(statement,1);
 char *manufacturer = (char *)sqlite3_column_text(statement,2);
 char *details = (char *)sqlite3_column_text(statement,3);
 char *countryOfOrigin = (char *)sqlite3_column_text(statement,6);
 char *image = (char *)sqlite3_column_text(statement,7);
 
 // Set all the attributes of the product
 product.ID = sqlite3_column_int(statement,0);
 product.name = (name) ? [NSString stringWithUTF8String:name] : @"";
 product.manufacturer = (manufacturer) ? [NSString
 stringWithUTF8String:manufacturer] : @"";
 product.details = (details) ? [NSString stringWithUTF8String:details] : @"";
 product.price = sqlite3_column_double(statement,4);
 product.quantity = sqlite3_column_int(statement,5);
 product.countryOfOrigin = (countryOfOrigin) ? [NSString
 stringWithUTF8String:countryOfOrigin] : @"";
 product.image = (image) ? [NSString stringWithUTF8String:image] : @"";
 
 // 将产品添加到Products数组中并且移到下一行
 [products addObject:product];
 }
 //释放和编译器语句有关的资源
 sqlite3_finalize(statement);
 }
 else {
 NSLog(@"Problem with the database:");
 NSLog(@"%d",sqlResult);
 }
 return products;
}
@end

在Controller中使用来显示在View中的代码：

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    DBAccess *dbAccess = [[DBAccess alloc] init];
    
    self.products = [dbAccess getAllProducts]; //前面应该定义了products这个属性。
    
    [dbAccess closeDatabase];
    
}

源代码下载连接：

http://www.wrox.com/WileyCDA/WroxTitle/Professional-iOS-Database-Application-Programming-2nd-Edition.productCd-1118391845,descCd-DOWNLOAD.html

（编辑：李大同）

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