iPhone/iPad sqlite3数据库操作之fmdb

首先来看一下如何使用sqlite3来实现数据库的操作，先上码吧。。。

头文件如下：

@interface DbBase :NSObject
{
   
sqlite3  *database;        
// database
   
NSString *filePath;        
// File path.
   
BOOL      isOpen;          
// Database is opened.
    NSString *defaultDb; 
     // if db is not exist, so we use the default db named db.db
}
@propertyBOOL 
    isOpen;    // database is opened?
@propertyNSString
*filePath;  // save the database file path

// open the database and return the result of operation
// params - file : database name
// return TRUE or FALSE if database is opened.
- (BOOL) open:(NSString*) file;

// close opened database
- (void) close;                   

// execute sql commands like CRUD
// params - sql   : sql string
//          param : values
// return 
- (BOOL)execute:(NSString *)sql paramArray:(NSArray *)param;

// do some initializations when this object is created.
- (id) init;

// clear
- (void) dealloc;

@end
实现方法如下：

@implementation DbBase

@synthesize isOpen;
@synthesize filePath;

- (BOOL) open:(NSString*) file
{
   
BOOL success;
   NSFileManager *fileManager = [NSFileManagerdefaultManager];
    NSError *error;
   NSArray *paths =NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask,YES);
   
NSString *documentsDirectory = [paths objectAtIndex:0];
   
NSString *writableDBPath = [documentsDirectory
stringByAppendingPathComponent: file];
    
   // check file is exist. create one if file is not exist.
    success = [fileManagerfileExistsAtPath: writableDBPath];
   
if (!success) {
       
NSString *defaultDBPath = [[[NSBundle
mainBundle] resourcePath] 
                                  stringByAppendingPathComponent:defaultDb];
        
        success = [fileManagercopyItemAtPath:defaultDBPathtoPath:writableDBPatherror:&error];
       
if (!success) {
           NSLog(@"Failed
to create writable database file with message '%@'.", 
                      [errorlocalizedDescription]);
        }
    }
    
   
isOpen = FALSE;
   // open database file
    
if (sqlite3_open([writableDBPath
UTF8String], &database) ==
SQLITE_OK) {
        
isOpen = TRUE;
     }else {
        NSLog(@"open
database failed.");
        
isOpen = FALSE;
     }
    
   
return isOpen;
}

- (void) close
{
   sqlite3_close(database);
}

- (BOOL)execute:(NSString *)sql paramArray:(NSArray *)param 
{
   if (!isOpen)returnFALSE;
   
sqlite3_stmt *statement = nil;
   
int success = sqlite3_prepare_v2(database, [sqlUTF8String], -1, &statement,NULL);
   
if (success != SQLITE_OK) {
       NSLog(@"Error:
failed to prepare");
       
return NO;
    }
    
   
NSInteger max = [param count];
   
for (int i=0; i<max; i++) {
       
NSString *temp = [param objectAtIndex:i];
       
sqlite3_bind_text(statement, i+1, [tempUTF8String], -1,SQLITE_TRANSIENT);
    }
    success =
sqlite3_step(statement);
   
sqlite3_finalize(statement);
   
if (success == SQLITE_ERROR) {
       NSLog(@"Error:
failed to insert into the database");
       
return NO;
    }
   returnTRUE;
}

- (id) init
{
   
self = [super
init];
   defaultDb =@"db.db";
    
   returnself;
}

- (void) dealloc
{
    [selfclose];
   
isOpen = FALSE;
}
@end

基本功能也可以实现，在网上发现一个对sqlite3数据库操作的一个封装类（fmdb），看起来比较优雅，拿来研究一下。首先从这个网址：https://github.com/ccgus/fmdb下载fmdb的源码，将Src文件夹下的文件复制到您当前工程文件目录下，然后将代码导入到您的工程中（除了fmdb.m），编译一下，如果有错误，可能是您未导
12484
入slite3的链接库，打开Build Phases，如将libsqlite3.dylib添加进来，然后重新编译。

使用fmdb操作sqlite3数据库将变的十分简单，下面我们来看一下对一个用户数据表的CRUD操作：

     首先定义用户对象，我在这里只简单的定义三个属性信息

     

@interface User :NSObject<NSCopying>

@propertyNSInteger  userId;
@propertyNSString * userName;
@propertyNSString * password;

@end

      下面是其m文件下的实现代码

@implementation User

@synthesize userId;
@synthesize userName;
@synthesize password;

- (id) init
{
   
self = [super
init];
    
   return 
self;
}

-(id) copyWithZone: (NSZone *) zone
{
   
User * user = [[User
allocWithZone: zone] init];
   
if (user) {
        [user
setUserId:userId];
        [user
setUserName:[userName
copy]];
        [user
setPassword:[password
copy]];
    }
   
   
return user;
}

- (NSString*) description
{
   return [NSStringstringWithFormat:@"userId:%d
userName:%@ password:%@", 
           userId,
userName,password];
}

@end

再来看一下对用户的数据库UserDbService的定义及实现，

@interface UserDbService :NSObject

// properties define

@propertyFMDatabase * db;

// properties end

// methods

// get one user by it's id
- (BOOL) getUserById:(NSInteger)userId result:(User*)user;

// insert one user into the database
- (BOOL) saveUser:(User*) user;

// update user
- (BOOL) updateUser:(User*)user;

// delete user
- (BOOL) deleteUser:(User*)user;

// check user
- (BOOL) userIsExist:(NSString*)userName;

// user login
- (BOOL) userLogin:(User*)user;

// get one user from a set
- (BOOL) getFromTable:(FMResultSet*)rs result:(User*)user;

// get all users
- (void) getAll:(NSMutableArray*)userArr;

@end

@implementation UserDbService

@synthesize db;

-(BOOL) getUserById:(NSInteger)userId result:(User*)user
{
   NSAssert(db,@"database
is not opened.");
   
if (!user) return
FALSE;
    
   
if (db) {
       NSString * sql = [NSStringstringWithFormat:@"select
* from t_user where userId = %d", userId];
       
FMResultSet * rs = [db
executeQuery: sql];
       
while ([rs next]) {
           
if ([self
getFromTable:rs result:user]) 
               
return TRUE;
        }
    }
    
   return
FALSE;
}

- (BOOL) saveUser:(User*)user
{
   
if (!db) {
       return
FALSE;
    }
    
   NSString * sql = [NSStringstringWithFormat:@"insert
into t_user(userName, password) values(?,?)"];
   
NSArray  * params = [NSArray
arrayWithObjects: 
                         user.userName,
                         user.password, 
                        nil];
   return [dbexecuteUpdate:sql
withArgumentsInArray:params];
}

- (BOOL) updateUser:(User*)user
{
   
if (!db) {
       return
FALSE;
    }
    
   NSString * sql = [NSStringstringWithFormat:@"update
t_user(userName, password) values(?,?) where userId=?"];
   
NSArray  * params = [NSArray
arrayWithObjects: 
                         user.userName,
                         user.password,
                         [NSNumbernumberWithInt:user.userId],
                        nil];
   return [dbexecuteUpdate:sql
withArgumentsInArray:params];
}

- (BOOL) deleteUser:(User*)user
{
   if (!db)return
FALSE;
    
   NSString * sql = [NSStringstringWithFormat:@"delete
from t_user where userId = %d", user.userId];
   
return [db
executeUpdate:sql];
}

- (BOOL) userIsExist:(NSString*)userName
{
   
if (!db) {
       return
FALSE;
    }
    
   NSString * sql = [NSStringstringWithFormat:@"select
count(*) from t_user where userName='%@')", userName];
   
FMResultSet *rs = [db
executeQuery: sql];
   
return [rs columnCount] >
0 ? TRUE :
FALSE;
}

- (BOOL) userLogin:(User*)user
{
   if (!db)return
FALSE;
    
   NSString * sql = [NSStringstringWithFormat:@"select
count(*) from t_user where userName=? password=?)"];
   
NSArray * params = [NSArray
arrayWithObjects:
                        user.userName,
                        user.password,
                       nil];
   FMResultSet *rs = [dbexecuteQuery:sql
withArgumentsInArray:params];
   
while ([rs next]) {
        [selfgetFromTable:rs
result:user];
    }
    
   
if (user.userId >
0) {
       
return  TRUE;
    }
    
   return
FALSE;
}

- (void) getAll:(NSMutableArray*)userArr
{
   
if (!db)
return;
    
   NSString * sql =@"select
* from t_user order by userName asc";
   
FMResultSet *rs = [db
executeQuery:sql];
   
while ([rs next]) {
       
User *tmp = [[User
alloc] init];
        [selfgetFromTable:rs
result:tmp];
        [userArr
addObject:tmp];
    }
}

- (BOOL) getFromTable:(FMResultSet*)rs result:(User*)user
{
   
if (!rs || !user) {
       return
FALSE;
    }
    
    [usersetUserId:[rs
intForColumn:@"userId"]];
    [usersetUserName:[rs
stringForColumn:@"userName"]];
    [usersetPassword:[rs
stringForColumn:@"password"]];
    
   return
TRUE;
}

@end

假如在您的目录下有db.db文件，测试代码如下

- (IBAction)onTest:(id)sender 
{
   NSString *dbPath =@"/Users/wyffywwyf/Desktop/db.db";
    
   FMDatabase *db = [FMDatabasedatabaseWithPath:dbPath];
   
if (db == nil || ![dbopen]) {
       NSLog(@"open
database failed.");
    }else {
       NSLog(@"open
database successed.");
    }
    
   
UserDbService *userService = [[UserDbServicealloc]
init];
    [userService
setDb:db];
    
   NSMutableArray *arr = [NSMutableArrayarray];
    [userService
getAll:arr];
   
for (User * u
in arr) {
       
NSLog(@"%@", u);
    }
    
    [db
close];
}

非常的简单，希望对您有所帮助。