## 10.3.6 Character String Literal Character Set and Collation 

Every character string literal has a character set and a collation. 

For the simple statement SELECT ’ string ’ , the string has the connection default character set and collation defined by the character_set_connection  and collation_connection  system variables. 

A character string literal may have an optional character set introducer and COLLATE  clause, to designate it as a string that uses a particular character set and collation: 

[_ charset_name ]’ string ’ [COLLATE collation_name ] 

The _ charset_name  expression is formally called an introducer . It tells the parser, “the string that follows uses character set charset_name .”  An introducer does not change the string to the introducer character set like CONVERT()  would do. It does not change the string value, although padding may occur. The introducer is just a signal. See Section 10.3.8, “Character Set Introducers” . 

Examples: 

SELECT ’abc’; SELECT _latin1’abc’; SELECT _binary’abc’; SELECT _utf8mb4’abc’ COLLATE utf8mb4_danish_ci; 

Character set introducers and the COLLATE  clause are implemented according to standard SQL specifications. 

MySQL determines the character set and collation of a character string literal in the following manner: 

•If both _charset_name  and COLLATE collation_name  are specified, character set charset_name and collation collation_name  are used. collation_name  must be a permitted collation for charset_name . 

•If _charset_name  is specified but COLLATE  is not specified, character set charset_name  and its default collation are used. To see the default collation for each character set, use the SHOW CHARACTER SET  statement or query the INFORMATION_SCHEMA CHARACTER_SETS  table. 

•If _charset_name  is not specified but COLLATE collation_name  is specified, the connection default character set given by the character_set_connection  system variable and collation collation_name  are used. collation_name  must be a permitted collation for the connection default character set. 

•Otherwise (neither _charset_name  nor COLLATE collation_name  is specified), the connection default character set and collation given by the character_set_connection  and collation_connection  system variables are used. 

Examples: 

•A nonbinary string with latin1  character set and latin1_german1_ci  collation: 

SELECT _latin1’Müller’ COLLATE latin1_german1_ci; 

•A nonbinary string with utf8mb4  character set and its default collation (that is, utf8mb4_0900_ai_ci ): 

SELECT _utf8mb4’Müller’; 

•A binary string with binary  character set and its default collation (that is, binary ): 

