SQLite

Expr *sqlite3PExpr(
  Parse *pParse,          /* Parsing context */
  int op,                 /* Expression opcode */
  Expr *pLeft,            /* Left operand */
  Expr *pRight,           /* Right operand */
  const Token *pToken     /* Argument token */
){
  Expr *p;
  if( op==TK_AND && pLeft && pRight ){
    /* Take advantage of short-circuit false optimization for AND */
    p = sqlite3ExprAnd(pParse->db, pLeft, pRight);
  }else{
    p = sqlite3ExprAlloc(pParse->db, op, pToken, 1);
    sqlite3ExprAttachSubtrees(pParse->db, p, pLeft, pRight);
  }
  if( p ) {
    sqlite3ExprCheckHeight(pParse, p->nHeight);
  }
  return p;
}

/*
** Return 1 if an expression must be FALSE in all cases and 0 if the
** expression might be true.  This is an optimization.  If is OK to
** return 0 here even if the expression really is always false (a 
** false negative).  But it is a bug to return 1 if the expression
** might be true in some rare circumstances (a false positive.)
**
** Note that if the expression is part of conditional for a
** LEFT JOIN, then we cannot determine at compile-time whether or not
** is it true or false, so always return 0.
*/
static int exprAlwaysFalse(Expr *p){
  int v = 0;
  if( ExprHasProperty(p, EP_FromJoin) ) return 0;
  if( !sqlite3ExprIsInteger(p, &v) ) return 0;
  return v==0;
}

/*
** Join two expressions using an AND operator.  If either expression is
** NULL, then just return the other expression.
**
** If one side or the other of the AND is known to be false, then instead
** of returning an AND expression, just return a constant expression with
** a value of false.
*/
Expr *sqlite3ExprAnd(sqlite3 *db, Expr *pLeft, Expr *pRight){
  if( pLeft==0 ){
    return pRight;
  }else if( pRight==0 ){
    return pLeft;
  }else if( exprAlwaysFalse(pLeft) || exprAlwaysFalse(pRight) ){
    sqlite3ExprDelete(db, pLeft);
    sqlite3ExprDelete(db, pRight);
    return sqlite3ExprAlloc(db, TK_INTEGER, &sqlite3IntTokens[0], 0);
  }else{
    Expr *pNew = sqlite3ExprAlloc(db, TK_AND, 0, 0);
    sqlite3ExprAttachSubtrees(db, pNew, pLeft, pRight);
    return pNew;
  }
}

  }
} {}
do_test in-7.5 {
  execsql {
    SELECT a FROM t1 WHERE a IN (5) AND b NOT IN ();
  }
} {5}
do_test in-7.6.1 {
  execsql {
    SELECT a FROM ta WHERE a IN ();
  }
} {}
do_test in-7.6.2 {
  db status step
} {0}
do_test in-7.7 {
  execsql {
    SELECT a FROM ta WHERE a NOT IN ();
  }
} {1 2 3 4 6 8 10}

do_test in-7.8.1 {
  execsql {
    SELECT * FROM ta LEFT JOIN tb ON (ta.b=tb.b) WHERE ta.a IN ();
  }
} {}
do_test in-7.8.2 {
  db status step
} {0}

do_test in-8.1 {
  execsql {
    SELECT b FROM t1 WHERE a IN ('hello','there')
  }
} {world}
do_test in-8.2 {