Mysql8 :What character set should the server translate statements to after receiving them when using introducer?

Question

According to the MYSQL8 docs:

Several questions about character set and collation handling for client connections can be answered in terms of system variables:

• What character set are statements in when they leave the client?
  The server takes the character_set_client system variable to be the character set in which statements are sent by the client.
  
• What character set should the server translate statements to after receiving them?
  
  To determine this, the server uses the character_set_connection and collation_connection system variables:
  
  The server converts statements sent by the client from character_set_client to character_set_connection. Exception: For string literals that have an introducer such as _utf8mb4 or _latin2, the introducer determines the character set. See Section 10.3.8, “Character Set Introducers”.

After reading the quote, I am confused. Does the document want to tell us that if an introducer is used, the introducer will replace the character_set_connection encoding?

Or let me give a specific example, is there any difference between executing select _gbk '中文'; and executing select '中文';? How does the introducer _gbk affect the server's character set conversion for statements?

I hope someone can help me explain the meaning of the official descriptions and this example of mine, thank you very much.

The reference link : charset-connection

Answer 1

The difference between select _gbk '中文' and select '中文' is that in select _gbk '中文', '中文' is understood, when it is being transmitted from the client to the server, to be in the GBK character set, whereas in select '中文', '中文' is understood to be in the character set found in character_set_client.