How to call "ClassMethod" in SQL statement？

Remove

FROM "procedure".day01

You can't run a SQL statement from the console prompt.
You need to start the SQL shell first:

SAMPLES>do $system.SQL.Shell()
SQL Command Line Shell
----------------------------------------------------
 
The command prefix is currently set to: <<nothing>>.
Enter <command>, 'q' to quit, '?' for help.
[SQL]SAMPLES>SELECT . . . . your statement

You should take a look to Using Caché SQL !

Executing SQL
https://docs.intersystems.com/latest/csp/docbook/Doc.View.cls?KEY=GSQL_basics#GSQL_basics_executing 

Using the SQL Shell Interface
https://docs.intersystems.com/latest/csp/docbook/Doc.View.cls?KEY=GSQL_shell