Question

I am trying to delete some entries in my sqlite database on my iPhone app, but am getting a weird error.

Here is my code:

if(sqlite3_open([databasePath UTF8String], &yerocDB)==SQLITE_OK)
{   
    sqlite3_stmt *compiledstatement;

    NSString *deleteSql=[NSString stringWithFormat: @"delete from Favorites_Table where playlist_name = Studying and date = 1/1/2012"];
    const char *sqlstmt = [deleteSql UTF8String];

    if(sqlite3_prepare_v2(yerocDB, sqlstmt, -1, &compiledstatement, NULL)==SQLITE_OK)
    {
        int result = sqlite3_step(compiledstatement);

        if(SQLITE_DONE != result)

            NSAssert1(0,@"Error while creating delete statement => %s",sqlite3_errmsg(yerocDB) );
    }else{
        NSLog(@"didn't delete error: %s", sqlite3_errmsg(yerocDB));
    }
    sqlite3_finalize(compiledstatement);
}

but then I get the error:

didn't delete error: no such column: Studying

playlist_name and date are my columns…Why is it saying the “Studying” is not a column?

Answer 1

You need to wrap Studying in single quotes. And your date.

This:

delete from Favorites_Table 
where playlist_name = Studying and date = 1/1/2012

Should be this:

delete from Favorites_Table 
where playlist_name = 'Studying' and date = '2012-01-01'

The reason is that if you don’t put it in single quotes, the parser will think it’s a column name. In your first query, you were trying to delete from Favorites_Table where the playlist_name column equalled the Studying column. Henceforth your error, “No such column.”

And once you fixed the quotes around studying, your date was going to throw an error, too. Dates use ISO format (yyyy-mm-dd) to compare. Don’t use the localized mm/dd/yyyy or dd/mm/yyyy formats, as a rule of thumb.