Question

我是第一次在iPhone上试用SQLite。我面临的错误是下面的ecode中的语句sqlite3_prepare_v2(database, sql, -1, &selectstmt, NULL) == SQLITE_OK返回false并且没有显示任何内容。

以下是我的代码：

+ (void) getInitialDataToDisplay:(NSString *)dbPath {

dbTryAppDelegate *appDelegate = (dbTryAppDelegate *)[[UIApplication sharedApplication] delegate];

if (sqlite3_open([dbPath UTF8String], &database) == SQLITE_OK) {

    const char *sql = "select name,id from studtry";
    sqlite3_stmt *selectstmt;
//below line is never executed and its else part is also not executed.
    if(sqlite3_prepare_v2(database, sql, -1, &selectstmt, NULL) == SQLITE_OK) {

        while(sqlite3_step(selectstmt) == SQLITE_ROW) {

            NSInteger primaryKey = sqlite3_column_int(selectstmt, 0);
            stud *coffeeObj = [[stud alloc] initWithPrimaryKey:primaryKey];
            coffeeObj.studName = [NSString stringWithUTF8String:(char *)sqlite3_column_text(selectstmt, 0)];

            //coffeeObj.isDirty = NO;

            [appDelegate.studArray addObject:coffeeObj];
          //  [coffeeObj release];
        }
    }
}
else
    sqlite3_close(database); //Even though the open call failed, close the database connection to release all the memory.
}

我哪里出错了？我该如何解决？

Answer 1

检查数据库路径，数据库扩展以及相同的表格＆amp;字段。

反正，

使用它而不是直接使用const string ::

NSString *sqlStr = [NSString stringWithFormat:@"select name,id from studtry"];

const char *sql = [sqlStr UTF8String];

while循环结束语句后，

sqlite3_finalize(selectstmt);

然后，在If条件之后，

 sqlite3_close(database);

无需写入其他部分。

希望它对你有用。感谢。

Answer 2

根据你的代码，所有的东西都是abs正确但我认为你传递错误的DBPath或者可能是db文件不对，请检查这两点

Answer 3

首先从应用程序＆amp;中删除您的应用程序模拟器文件夹。然后创建名为:: Practise.sqlite3的数据库（SQLite3的类型）

然后编写此方法进行复制：

- (void) copyDatabaseIfNeeded {

   NSFileManager *fileManager = [NSFileManager defaultManager];
   NSError *error;
   dbPath = [self getDBPath];

       BOOL success = [fileManager fileExistsAtPath:dbPath];

   if(!success) {
        NSString *defaultDBPath = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:@"Practise.sqlite3"];
        success = [fileManager copyItemAtPath:defaultDBPath toPath:dbPath error:&error];
   if (!success)
        NSAssert1(0, @"Failed to create writable database file with message '%@'.", [error localizedDescription]);
   }
}


- (NSString *) getDBPath {

      NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask,YES);
      NSString *documentsDir = [paths objectAtIndex:0];

      return [documentsDir stringByAppendingPathComponent:@"Practise.sqlite3"];
}

您可以随时复制，

[self copyDatabaseIfNeeded];

然后，检查您的结果。希望它能起作用。

sqlite3_prepare_v2不会在iPhone上返回sqlite_ok

3 个答案: