utf8-to-utf8mb4 mysql支持全部unicode

Are you using MySQL’s 

utf8

 charset in your databases? In this write-up I’ll explain why you should switch to 

utf8mb4

 instead,
and how to do it.

UTF-8

The UTF-8 encoding can represent every symbol in the Unicode character set, which ranges from U+000000 to U+10FFFF. That’s 1,114,112 possible
symbols. (Not all of these Unicode code points have been assigned characters yet, but that doesn’t stop UTF-8 from being able to encode them.)

UTF-8 is a variable-width encoding; it encodes each symbol using one to four 8-bit bytes. Symbols with lower numerical code point values are encoded using fewer bytes. This way, UTF-8 is optimized for the common case where ASCII characters and other BMP
symbols (whose code points range from U+000000 to U+00FFFF) are used — while still allowing astral symbols (whose code points range from U+010000 to U+10FFFF) to be stored.

MySQL’s 

utf8

For a long time, I was using MySQL’s 

utf8

 charset for databases, tables, and columns, assuming it mapped to the UTF-8 encoding
described above. By using 

utf8

, I’d be able to store any symbol I want in my database — or so I thought.

While writing about JavaScript’s internal character encoding, I noticed that there was no way to insert the U+1D306 TETRAGRAM FOR
CENTRE (