Information Functions -> ’utf8’ The return values have the meanings shown in the following table. Lower values have higher precedence. For more information, see Section 10.8.4, “Collation Coercibility in Expressions” . Returns the collation of the string argument. Returns the connection ID (thread ID) for the connection. Every connection has an ID that is unique among the set of currently connected clients. The value returned by  CONNECTION_ID()  is the same type of value as displayed in the  ID  column of the  INFORMATION_SCHEMA.PROCESSLIST  table, the  Id  column of  SHOW PROCESSLIST  output, and the  PROCESSLIST_ID  column of the Performance Schema  threads  table. mysql>  SELECT CONNECTION_ID(); mysql>  SELECT COLLATION(’abc’); -> ’utf8_general_ci’ mysql>  SELECT COLLATION(_utf8mb4’abc’); -> ’utf8mb4_0900_ai_ci’ mysql>  SELECT COLLATION(_latin1’abc’); -> ’latin1_swedish_ci’ mysql>  SELECT COERCIBILITY(’abc’ COLLATE utf8_swedish_ci); -> 0 mysql>  SELECT COERCIBILITY(USER()); -> 3 mysql>  SELECT COERCIBILITY(’abc’); -> 4 mysql>  SELECT COERCIBILITY(1000); -> 5 Returns the collation coercibility value of the string argument. • COERCIBILITY( str ) • COLLATION( str ) • CONNECTION_ID() 2281 Coercibility Meaning Example 0 Explicit collation Value with  COLLATE  clause 1 No collation Concatenation of strings with different collations 2 Implicit collation Column value, stored routine parameter or local variable 3 System constant USER()  return value 4 Coercible Literal string 5 Numeric Numeric or temporal value 5 Ignorable NULL  or an expression derived from  NULL