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我正在尝试从 sqlite 数据库中提取数据。我添加了“libsqlite3.0.dylib”文件并将创建的 sqlite DB 复制到我的应用程序文件夹中。我在 appdelegate 文件中创建了两个方法。他们是

//To copy DB
- (void) copyDatabaseIfNeeded {

    //Using NSFileManager we can perform many file system operations.
    NSFileManager *fileManager = [NSFileManager defaultManager];
    NSError *error;
    NSString *dbPath = [self getDBPath];
    BOOL success = [fileManager fileExistsAtPath:dbPath];

    if(!success) {
        NSLog(@"DB File %@ does not exists", dbPath);
        NSString *defaultDBPath = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:@"tms.sqlite"];
        success = [fileManager copyItemAtPath:defaultDBPath toPath:dbPath error:&error];

        NSLog(@"Successfully copied db file to path %@", dbPath);
        if (!success)
            NSLog(@"Failed to create writable database file with message '%@'.", [error localizedDescription]);
    } else {
        NSLog(@"DB File %@ already exists", dbPath);
    }
}

//To get DB path
-(NSString *)getDBPath{
    NSArray *paths=NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentDir=[paths objectAtIndex:0];
    return [documentDir stringByAppendingPathComponent:@"sampleDB.sqlite"];
}

我在 didFinishLaunchingWithOptions 中调用了 copyDatabaseIfNeeded()，并且在 ViewController.m 文件中添加了一种方法。那是

-(void)Display
{
    SqlitAppDelegate *appDelegate=(SqlitAppDelegate *)[UIApplication sharedApplication].delegate;
    NSString *dbPath=[appDelegate getDBPath];
    if (sqlite3_open([dbPath UTF8String], &myDB) == SQLITE_OK)
    {
        NSLog(@"Database opned successflly");
        const char *sql = "select * from sampleTable";
        NSLog(@"%s",sql);
        sqlite3_stmt *selectstmt;
        if(sqlite3_prepare_v2(myDB, sql, -1, &selectstmt, NULL) == SQLITE_OK)
            NSLog(@"Prepared successfully");
        else
        {
            NSLog(@"Preparation failed");
            NSLog(@"%s",sqlite3_errmsg(myDB));
            NSLog(@"%d",sqlite3_errcode(myDB));
        }


    }
    else
        NSLog(@"Couldn't open database");


}

我在 didViewLoad 方法中调用了这个方法。

我得到以下输出：

  • 2013-03-20 12:02:24.026 SqliteSample2[951:11303] 数据库成功打开
  • 2013-03-20 12:02:24.027 SqliteSample2[951:11303] 从 sampleTable 中选择 *
  • 2013-03-20 12:02:24.028 SqliteSample2[951:11303] 准备失败
  • 2013-03-20 12:02:24.029 SqliteSample2[951:11303] 没有这样的表：sampleTable
  • 2013-03-20 12:02:24.029 SqliteSample2[951:11303] 1

有人告诉我做什么吗？？？？？？

提前致谢...........

4

1 回答 1

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Import SqlitAppDelegate in your view controller and make Object like SqlitAppDelegate *app after @implementation ViewController

In viewDidLoad write

    app= (SqlitAppDelegate *)[[UIApplication sharedApplication]delegate];

    databasepath = [app getDBPath];

    if(sqlite3_open([databasepath UTF8String], &dbAssessor) == SQLITE_OK) 
    {
        NSString *sql = [NSString stringWithFormat:@"select * from SampleTable ;"];

        sqlite3_stmt *selectstmt;
        const char *sel_query=[sql UTF8String];

        if(sqlite3_prepare(dbAssessor, sel_query, -1, &selectstmt, NULL) == SQLITE_OK)
        {
            while(sqlite3_step(selectstmt) == SQLITE_ROW)
            {   
                NSLog(@"Prepared Successfully...");
            }
        }
        sqlite3_finalize(selectstmt);
    }
    else
        sqlite3_close(dbAssessor);

Please try this code and pass me the result. Enjoy !!!

于 2013-03-20T07:07:56.530 回答