sql_list:
    sql ';' 
  | sql_list sql ';' 
  ;

sql:
    create_table table '(' base_table_element_commalist ')'
  | insert_into table opt_column_commalist values_spec
  | select selection from_clause opt_where_clause
  | update table SET assignment_commalist opt_where_clause
  | DELETE FROM table opt_where_clause
  ;

/* ----- create table statement ----- */
create_table:
    CREATE TABLE
  ;

base_table_element_commalist:
    column_def
  | base_table_element_commalist ',' column_def
  ;

column_def:
    column data_type 
  ;

/* ----- insert into statement ----- */
insert_into :
    INSERT INTO
  ;

opt_column_commalist:
    /* empty */
  | '(' column_commalist ')'
  ;

column_commalist:
    column
  | column_commalist ',' column
  ;

values_spec:
    VALUES '(' insert_atom_commalist ')'
  ;

insert_atom_commalist:
    atom
  | insert_atom_commalist ',' atom
  ;

/* ----- select statement ----- */
select:
    SELECT
  ;

selection:
    '*'
  | column_ref_commalist
  ;

column_ref_commalist:
    column_ref
  | column_ref_commalist ',' column_ref
  ;

from_clause:
    FROM table
  ;

/* ----- update statement ----- */

update:
    UPDATE
  ;

assignment_commalist:
    /* empty */
  | assignment
  | assignment_commalist ',' assignment        
  ;
        
assignment:                    
    column '=' scalar_exp
  ;

/* ----- opt_where_clause & its decendents ----- */
opt_where_clause:
    /* empty - return BooleanAtom TRUE */
  | WHERE search_condition
  ;

search_condition:
    search_condition OR search_condition 
  | search_condition AND search_condition 
  | NOT search_condition
  | '(' search_condition ')'
  | predicate                     
  ;    

predicate:      
    scalar_exp COMPARISON scalar_exp
  | scalar_exp LIKE atom 	/* scalar_exp & atom must be string type */
  | scalar_exp NOT LIKE atom 	/* scalar_exp & atom must be string type */
  ;                                                 

scalar_exp:
    scalar_exp '+' scalar_exp 
  | scalar_exp '-' scalar_exp 
  | scalar_exp '*' scalar_exp
  | scalar_exp '/' scalar_exp 
  | '+' scalar_exp %prec UMINUS  
  | '-' scalar_exp %prec UMINUS  
  | atom  
  | column_ref 
  | '(' scalar_exp ')' 
  ;

atom:
    STRING 
  | INTNUM 
  ;

	/* miscellaneous */

column_ref:
    NAME
  | NAME '.' NAME	/* needs semantics */
  ;

		/* data types */

data_type:
    CHARACTER
  | INTEGER
  ;

	/* the various things you can name */

table:
    NAME
  ;

column:
    NAME

	/* tokens - defined by regular expression */
STRING:
	'[^'\n]*'

INTNUM:
	[0-9]+
    |	[0-9]+"."[0-9]*
    |	"."[0-9]*

NAME:
	[A-Za-z][A-Za-z0-9_]*