Question

如何从sqlite数据库中检索数据？返回值为零。

-(id)init{

    if(self==[super init]){
        database=nil;
    }
    return self;
}

-(void)addDetails:(NSString *)_name withAddress:(NSString *)_address withAge:(int)_age withMobile:(double)_mobile{

   // NSLog(@"in db class --->%@ %@ %d %f",_name,_address,_age,_mobile);
   // NSString *name=@"...has done it";

      if([self openDBConnection] == TRUE) {

        const char *sql= "insert into Personal (Name,Address,Age,Mobiel) Values(?, ?, ?, ?)";

        sqlite3_stmt *updateUser_stmt = nil;
        NSInteger retVal = sqlite3_prepare_v2(database, sql, -1, &updateUser_stmt, NULL);
        NSLog(@"the return value is %d",retVal);
        if(retVal == SQLITE_OK)
        {
            sqlite3_bind_text (updateUser_stmt , 1, [_name UTF8String],-1,SQLITE_STATIC);
            sqlite3_bind_text (updateUser_stmt , 2, [_address UTF8String], -1, SQLITE_STATIC);
            sqlite3_bind_int(updateUser_stmt, 3, _age); 
            sqlite3_bind_double(updateUser_stmt, 4, _mobile);
            // sqlite3_bind_text (updateUser_stmt , 4, [HomeUserDetails.strName UTF8String], -1, SQLITE_STATIC);

            NSInteger resultInt = sqlite3_step(updateUser_stmt );
            if(SQLITE_DONE != resultInt)
                NSLog(@"Error while inserting data. '%s'", sqlite3_errmsg(database));
            else    
            {
                NSLog(@"MyA user details added to database");
            }
        }
        sqlite3_reset(updateUser_stmt );
        sqlite3_finalize(updateUser_stmt );
        updateUser_stmt = nil;
    }
}

-(void) modifyUserDetails :(Person *)_person
{
    NSLog(@"in update");
    if([self openDBConnection] == TRUE)
    {
        NSString *str = [NSString stringWithFormat:@"UPDATE Personal SET  Address='%@', Age='%d' , Mobiel='%d' WHERE Name='%@'",
                         _person.address, [_person getAge], [_person getMobile], _person.name];
        NSLog(@" String :%@",str);
        //NSString *str = [NSString stringWithFormat:@"UPDATE Room SET Access=1 WHERE RoomName='%@'",room.m_roomName];
        const char *sql = [str UTF8String];
        // [NSString stringWithFormat:@"UPDATE Room SET Access=%d WHERE RoomName=%@", access,room.m_roomName];
        sqlite3_stmt *updateUser_stmt = nil;
        if(sqlite3_prepare_v2(database, sql, -1, &updateUser_stmt, NULL) == SQLITE_OK)
        {
            sqlite3_bind_text(updateUser_stmt, 1, [_person.name UTF8String], -1, SQLITE_STATIC);
            sqlite3_bind_text(updateUser_stmt, 2, [_person.address UTF8String], -1, SQLITE_STATIC);
            sqlite3_bind_int(updateUser_stmt, 3, [_person getAge]);
            sqlite3_bind_double(updateUser_stmt, 4, [_person getMobile]);

            if(SQLITE_DONE != sqlite3_step(updateUser_stmt))
                NSLog(@"Error while updating data data. '%s'", sqlite3_errmsg(database));
        }
        sqlite3_reset(updateUser_stmt );
        sqlite3_finalize(updateUser_stmt );
        updateUser_stmt = nil;
    }
}

-(void)getUserDetails
{
    UIApplication *app=[UIApplication sharedApplication];
    appdlegate=app.delegate;
    if(appdlegate.arrayNames)
        [appdlegate.arrayNames removeAllObjects];
    NSLog(@"in get users");
    if([self openDBConnection] == TRUE) 
    {
        const char *sql = "select Name,Address,Age,Mobiel from Personal";//AccessLevel,HintA HintQ,Name,pwd
        sqlite3_stmt *getAccess_stmt = nil;
        NSInteger retVal = sqlite3_prepare_v2(database, sql, -1, &getAccess_stmt, NULL);
        if(retVal == SQLITE_OK)
        {
            while(sqlite3_step(getAccess_stmt) == SQLITE_ROW)
            {
                char* name = (char*) sqlite3_column_text(getAccess_stmt, 0);
                NSString *tmp;
                if (name != NULL){
                   tmp = [NSString stringWithUTF8String:name];
                    NSLog(@"value form db :%@",tmp);
                }
                [appdlegate.arrayNames addObject:tmp];
                char *addrs = (char*) sqlite3_column_text(getAccess_stmt, 1);
                if (addrs != NULL){
                    NSString *tmp = [NSString stringWithUTF8String:addrs];
                    NSLog(@"value from db :%@",tmp);
                }

                int age =sqlite3_column_int(getAccess_stmt,2);

                if(age){
                    NSLog(@"age from db: %d",age);
                }
                int mobile=sqlite3_column_double(getAccess_stmt, 3);
                ;
                if(mobile){
                    NSLog(@"mobile from db: %d",mobile);               
                }
            }
        }
        sqlite3_reset(getAccess_stmt );
        sqlite3_finalize(getAccess_stmt );
        getAccess_stmt = nil;
    }
}
-(Person *)getPerticular:(NSString *)_name
{ 
    Person *person;
    UIApplication *app=[UIApplication sharedApplication];
    appdlegate=app.delegate;
    NSLog(@"in get users");
    if([self openDBConnection] == TRUE) 
    {
         NSString *query = [NSString stringWithFormat:@"select  *from Personal where name ='%@'",_name];

        const char *sql =[query cStringUsingEncoding:NSASCIIStringEncoding];

        //const char *sql = "select  *from Personal where name=''";//AccessLevel,HintA HintQ,Name,pwd
        sqlite3_stmt *getAccess_stmt = nil;
        NSInteger retVal = sqlite3_prepare_v2(database, sql, -1, &getAccess_stmt, NULL);
        if(retVal == SQLITE_OK)
        {
             person=[[Person alloc]init];
            while(sqlite3_step(getAccess_stmt) == SQLITE_ROW)
            {

                char* name = (char*) sqlite3_column_text(getAccess_stmt, 0);
                NSString *tmp;
                if (name != NULL){
                    tmp = [NSString stringWithUTF8String:name];
                    NSLog(@"value perticular form db :%@",tmp);
                    person.name=tmp;
                }

                char *addrs = (char*) sqlite3_column_text(getAccess_stmt, 1);
                if (addrs != NULL){
                    NSString *tmp = [NSString stringWithUTF8String:addrs];
                    NSLog(@"value perticular from db :%@",tmp);
                    person.address=tmp;
                }

                int age =sqlite3_column_int(getAccess_stmt,2);

                if(age){
                    NSLog(@"perticular age from db: %d",age);
                    [person setAge:age];
                }
                int mobile=sqlite3_column_double(getAccess_stmt, 3);
                ;
                if(mobile){
                    NSLog(@"mobile from db: %d",mobile);
                    [person setMobile:mobile];
                }
            }
        }
        sqlite3_reset(getAccess_stmt );
        sqlite3_finalize(getAccess_stmt );
        getAccess_stmt = nil;
    }

    return person;
}

-(void)createConnection{

    NSError *error;
    NSArray *strdest=[NSArray arrayWithObjects:NSHomeDirectory(),@"Documents",DB_NAME,nil];

    dest=[NSString pathWithComponents:strdest];

    NSFileManager *manager=[NSFileManager defaultManager];
    NSArray *strSrc=[NSArray arrayWithObjects:NSHomeDirectory(),@"SqlliteDemo.app",DB_NAME, nil];
    NSString *source=[NSString pathWithComponents:strSrc];

    BOOL sucess=[manager fileExistsAtPath:dest];
    if(sucess){
        NSLog(@"alredy db copied to documents");
    }

    else {
        [manager copyItemAtPath:source toPath:dest error:&error];
        if(error){
            NSLog(@"NO Error");
        }
        else{
            NSLog(@"error is %@",error); 
        }
    }
}

-(BOOL)openDBConnection{
    [self createConnection];
    if(!database){
        if(sqlite3_open([dest UTF8String], &database)==SQLITE_OK){
            return TRUE;

        }else {
            return FALSE;
        }
    }
    return TRUE;
}

-(void)finalizeStatements{
    if(database)sqlite3_close(database);
}

Answer 1

请注意，下面显示的查询中存在一些问题，请在命令行中交叉检查相同的查询。即使看看你是否在你的项目中正确添加了db文件，这也可能会产生一些问题。

NSString *query = [NSString stringWithFormat:@"select  *from Personal where name ='%@'",_name];

如何从sqlite数据库中检索数据？获得返回值零

1 个答案: