MIT Press

Table 2

Proposed sketch for a SELECT statement. $TBL and $COL represent a table and a column, respectively. $AGG is one of {none, max, min, count, sum, avg}, $ARI is one of the arithmetic operators {none, -, +, *, / }, and $COND is one of the conditional operators {between, =, >, <, >=, <=, !=, in, like, is, exists}. $DIST and $NOT are Boolean variables representing the existence of keywords DISTINCT and NOT, respectively. $ORD is a binary value for keywords ASC/DESC, and $CONJ is one of conjunctions {AND, OR}. $VAL is the value for WHERE/HAVING condition; $SEL represents the slot for another SELECT statement.

CLAUSE	SKETCH
FROM	($TBL)⁺
SELECT	$DIST
SELECT	( $AGG ( $DIST₁$AGG₁$COL₁$ARI$DIST₂$AGG₂$COL₂ ) ) ⁺
ORDERBY	( ( $DIST₁$AGG₁$COL₁$ARI$DIST₂$AGG₂$COL₂ ) $ORD ) ^*
GROUPBY	($COL)^*
LIMIT	$NUM
WHERE	( $CONJ ( $DIST₁$AGG₁$COL₁$ARI$DIST₂$AGG₂$COL₂ )
HAVING	$NOT$COND$VAL₁\|$SEL₁$VAL₂\|$SEL₂ )^*
INTERSECT	$SEL
UNION
EXCEPT

CLAUSE	SKETCH
FROM	($TBL)⁺
SELECT	$DIST
SELECT	( $AGG ( $DIST₁$AGG₁$COL₁$ARI$DIST₂$AGG₂$COL₂ ) ) ⁺
ORDERBY	( ( $DIST₁$AGG₁$COL₁$ARI$DIST₂$AGG₂$COL₂ ) $ORD ) ^*
GROUPBY	($COL)^*
LIMIT	$NUM
WHERE	( $CONJ ( $DIST₁$AGG₁$COL₁$ARI$DIST₂$AGG₂$COL₂ )
HAVING	$NOT$COND$VAL₁\|$SEL₁$VAL₂\|$SEL₂ )^*
INTERSECT	$SEL
UNION
EXCEPT

View Large

This Feature Is Available To Subscribers Only