Question

您好我正在开发一个包含2个表的数据库dbmain 我的代码

NSString *docsDir;
NSArray *dirPaths;
dirPaths=NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);


// docsDir=[dirPaths objectAtIndex:0];
docsDir = dirPaths[0];
databasePath=[[NSString alloc]initWithString:[docsDir stringByAppendingPathComponent:@"dbDare.db"]];

NSFileManager *filemgr=[NSFileManager defaultManager];


if([filemgr fileExistsAtPath:databasePath]==NO)
{
    const char *dbpath=[databasePath UTF8String];
    if(sqlite3_open(dbpath, &contactDB)==SQLITE_OK)
    {
        char *errMsg;
        const char *sql_stmt =
        "CREATE TABLE IF NOT EXISTS tblUser(ID INTEGER PRIMARY KEY AUTOINCREMENT, StrName TEXT,Strusername  TEXT)";
        if (sqlite3_exec(contactDB, sql_stmt, NULL, NULL, &errMsg) != SQLITE_OK)
        {



            UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Failed to create table"
                                                            message:@"Failed to create table"
                                                           delegate:nil
                                                  cancelButtonTitle:@"OK"
                                                  otherButtonTitles:nil];
            [alert show];
            [alert release];
            //status.text = @"Failed to create table";
        }



            char *errMsg1;
            const char *sql_stmt1 =
            "CREATE TABLE IF NOT EXISTS tblVanish (ID INTEGER PRIMARY KEY AUTOINCREMENT, strfilepath TEXT,datesaved  TEXT)";
            if (sqlite3_exec(contactDB, sql_stmt1, NULL, NULL, &errMsg1) != SQLITE_OK)
            {

                UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Failed to create table"
                                                                message:@"Failed to create table"
                                                               delegate:nil
                                                      cancelButtonTitle:@"OK"
                                                      otherButtonTitles:nil];
                [alert show];
                [alert release];
                //status.text = @"Failed to create table";
            }
            sqlite3_close(contactDB);
    } else {
        // status.text = @"Failed to open/create database";
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Failed to create open/create database"
                                                        message:@"Failed to create open/create database"
                                                       delegate:nil
                                              cancelButtonTitle:@"OK"
                                              otherButtonTitles:nil];
        [alert show];
        [alert release];

}

在向表中添加记录后，我可以使用lita软件查看行但是在通过此代码重新检索行时

 const char *dbpath=[databasePath UTF8String];
int iVal=0;
  sqlite3_stmt *statement;
if (sqlite3_open(dbpath, &contactDB) == SQLITE_OK)
{
    NSString *querySQL = @"SELECT Strusername FROM tblUser";
    const char *query_stmt = [querySQL UTF8String];

    if (sqlite3_prepare_v2(contactDB, query_stmt, -1, &statement, NULL) == SQLITE_OK)
    {
        if (sqlite3_step(statement) == SQLITE_ROW)
        {
            while (sqlite3_step(statement) == SQLITE_ROW) {

               strname = [NSString stringWithFormat:@"Welcome %@" ,[NSString stringWithUTF8String:(char *)sqlite3_column_text(statement, 2)]];
            }



        } else {

        }
        sqlite3_finalize(statement);
    }
    sqlite3_close(contactDB);
}

我无法获取任何东西，因为使用ios在表格中没有显示行但我可以使用lita看到表格内的行，请建议我在哪里弄错了

Answer 1

您将数据库文件复制到文档目录的哪个位置？

这种情况对我来说很奇怪：

if([filemgr fileExistsAtPath:databasePath]==NO)

如果那里不存在数据库，为什么不将它复制到文档目录？

此外，您在if条件中创建表，意味着您正在尝试在不存在的db文件上创建表。

您可能希望先复制db文件，然后需要创建表格。

或

您需要更改条件，如：

if([filemgr fileExistsAtPath:databasePath]== YES)

使用2个表ios创建数据库

1 个答案: