Using lex-yacc check select statement in a SQL statement

YACC FILE

Source Code:
%{
#include 
void yyerror(char *);
int yylex();
%}
%token   SELECT STAR FROM WHERE HAVING GROUP_BY ORDER_BY ASC DESC NUMBER AND OR GREATER SMALLER
EQUAL GEQUAL LEQUAL NEQUAL  ID 
%start program
%%
program	:  SELECT name FROM tab clause where  ';' { printf("Successful parsing "); }
	;

where	: WHERE id '=' id clause 
	|
	;
name	:id
	|STAR
	;
tab	:ID
	|ID ',' tab
	;
clause	:GROUP_BY  id
	|GROUP_BY id HAVING cond
	|ORDER_BY  id asc
	|	
	;
asc	:ASC
	|DESC
	;
id	:id_dot
	|id_dot ',' id
	;
id_dot	:ID
	|ID '.' ID
	;
cond	:scond
	|scond lop cond
	;
scond	:nid
	|nid relop nid
	;
nid	:ID
	|NUMBER
	;
lop	:AND 
	|OR
	;
relop	:GREATER
	|SMALLER
	|EQUAL
	|GEQUAL
	|LEQUAL
	|NEQUAL
	;

%%

void yyerror(char *s)
{
printf("\n %s  ERROR",s);
}


int main()
{
yyparse();
return 0;
}



Lex FILE

Source Code:
 %{
int yywrap();
void yyerror(char *);
#include "y.tab.h" 
%}
%%
"group by"  {return  GROUP_BY;}
"having"  {return  HAVING;}
"order by"  {return  ORDER_BY;}
"select"  {return  SELECT;}
"from"  {return  FROM;}
"where"  {return  WHERE;}
"*"  {return  STAR;}
"asc"  {return  ASC;}
"desc"  {return  DESC;}
">"    {return GREATER;} 
"<"    {return SMALLER;} 
"=="    {return EQUAL;} 
">="    {return GEQUAL;} 
"<="    {return LEQUAL;} 

"!="    {return NEQUAL;} 
"||"    {return OR;} 
"&&"    {return AND;} 
[.{};,=] {return *yytext;}
[0-9]+   {return NUMBER;}
[a-zA-Z][a-zA-Z0-9]* {return ID;}
[ \t\n]+ ;
.   {printf("\n\n Error");}

%%

int yywrap()
{
return 1;
}