MySQL : SQL Connection error: Connection failed: Unknown MySQL server host 'localhost:3306' (0)

MySQL : SQL Connection error: Connection failed: Unknown MySQL server host 'localhost:3306' (0)
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On Google, Search for "hows tech developer connect"

I have a hidden feature that I promised to tell you about.
This is a YouTube's feature which works on Desktop.
First, Make sure the video is currently in playing mode.
Next, enter the letters 'awesome' on your keyboard.
It will change your youtube progress bar into a flashing rainbow.

Here's a brief description of who I am,
Salutations, my name is Delphi.
I can provide you with assistance to help you answer your questions.
MySQL : SQL Connection error: Connection failed: Unknown MySQL server host 'localhost:3306' (0)
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failed: error: 'localhost:3306' SQL Connection MySQL host : (0) Unknown Connection server MySQL