Grammar Specification

First of all, we need to specify the basic statement sql:

<statement> -> <dme-statement> | <dde-statement> | ...

Where the ... means the other type of statements that will be included after.

Now we have to specify the dme-statement that will include the SELECT statement.

<dme-statement> -> <selection> | <insertion> | <update> | <deletion>

For now we just need the <selection> specification.

<selection> -> <select-clause> FROM <from-list> <where-clause>

<select-clause> -> SELECT <distinct-clause> <select-list>

<distinct-clause> -> <empty> | DISTINCT

<select-list> -> <select-expr-list> | *

<select-expr-list> -> <select-expr> <select-comma-expr>

<select-comma-expr> -> , <select-expr> <select-comma-expr> | <empty>

<select-expr> -> <field-spec>

<from-list> -> <table-name> <from-list-expr>

<from-list-expr> -> <empty> | , <table-name> <from-list-expr>

<where-clause> -> <empty> | WHERE <boolean>

<nested-select> -> <empty> | <and-or> <table-name> <comparison> LPAR <selection> RPAR

<group-order-clause> -> <empty> | GROUP BY <field-spec-list> | ORDER BY <field-spec-list>

<boolean> -> <boolean-n> <boolean-o>

<boolean-o> -> OR <boolean-n> <boolean-o> | <empty>

<boolean-n> -> <boolean-prim> <boolean-n'>

<boolean-n'> -> AND <boolean-prim> <boolean-n'> | <empty>

<boolean-prim> -> <predicate>

<predicate> -> <expr> <relop> <expr>

<relop> -> NE | GT | LT | LWEDGE | RWEDGE | EQ

<expr> -> <constant> | <field-spec>

<constant> -> TEXT | NUMBER | DATE

<field-spec> -> <table-name> . <field-name>

<field-name> -> IDENTIFIER

<table-name> -> IDENTIFIER

<empty> -> EPSN