In SQL, keywords and identifiers are case-insensitive. Write a Lex program tha t recognizes the keywords SELECT, FROM, and WHERE (in any combination of capital and lower-case letters), and token ID,...

In SQL, keywords and identifiers are case-insensitive. Write a Lex program tha t recognizes the keywords SELECT, FROM, and WHERE (in any combination of capital and lower-case letters), and token ID, which for the purposes of this exercise you may take to be any sequence of letters and digits, beginning with a letter. You need not install identifiers in a symbol table, but tell how the "install" function would differ from tha t described for case-sensitive identifiers as in Fig. 3.23.

Fig. 3.23