Best way to test if a row exists in a MySQL table

You could also try EXISTS: and per the documentation, you can SELECT anything. Traditionally, an EXISTS subquery starts with SELECT *, but it could begin with SELECT 5 or SELECT column1 or anything at all. MySQL ignores the SELECT list in such a subquery, so it makes no difference.

Make first letter of a string upper case (with maximum performance)

Solution in different C# versions C# 8 with at least .NET Core 3.0 or .NET Standard 2.1 Since .NET Core 3.0 / .NET Standard 2.1 String.Concat() supports ReadonlySpan<char> which saves one allocation if we use .AsSpan(1) instead of .Substring(1). C# 8 C# 7 Really old answers This version is shorter. For a faster solution, take a look at Diego’s answer. Probably the fastest … Read more

Fastest way to remove first char in a String

The second option really isn’t the same as the others – if the string is “///foo” it will become “foo” instead of “//foo”. The first option needs a bit more work to understand than the third – I would view the Substring option as the most common and readable. (Obviously each of them as an individual statement … Read more

ADB stopping at (waiting for devices)

the only reason for this is that your PC is not recognizing Phone.which is a driver problem. You have to understand a few things before starting with the solution. you may know this too. when you are in your recovery adb gets into something like recovery mode(just framing some terms myself) in bootloader, it takes … Read more

How to get current time in milliseconds?

Simply use std::chrono. The general example below times the task “of printing 1000 stars”: Instead of printing the stars, you will place your sorting algorithm there and time measure it. Do not forget to enable the optimization flags for your compiler, if you intend to do some benchmarking, e.g. for g++, you need -O3. This is serious, check … Read more

Static linking vs dynamic linking

Dynamic linking can reduce total resource consumption (if more than one process shares the same library (including the version in “the same”, of course)). I believe this is the argument that drives it its presence in most environments. Here “resources” includes disk space, RAM, and cache space. Of course, if your dynamic linker is insufficiently flexible there is … Read more

HashSet vs. List performance

A lot of people are saying that once you get to the size where speed is actually a concern that HashSet<T> will always beat List<T>, but that depends on what you are doing. Let’s say you have a List<T> that will only ever have on average 5 items in it. Over a large number of cycles, if a single item … Read more

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)