SQLite

#endif

  return 1;
}
#endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */

/*
** A structure to keep track of all of the column values that are fixed to
** a known value due to WHERE clause constraints of the form COLUMN=VALUE.
*/
typedef struct WhereConst WhereConst;
struct WhereConst {
  Parse *pParse;   /* Parsing context */
  int nConst;      /* Number for COLUMN=CONSTANT terms */
  int nChng;       /* Number of times a constant is propagated */
  Expr **apExpr;   /* [i*2] is COLUMN and [i*2+1] is VALUE */
};

/*
** Add a new entry to the pConst object.  Except, do not add duplicate
** pColumn entires.
*/
static void constInsert(
  WhereConst *pConst,      /* The WhereConst into which we are inserting */
  Expr *pColumn,           /* The COLUMN part of the constraint */
  Expr *pValue             /* The VALUE part of the constraint */
){
  int i;
  assert( pColumn->op==TK_COLUMN );

  /* 2018-10-25 ticket [cf5ed20f]
  ** Make sure the same pColumn is not inserted more than once */
  for(i=0; i<pConst->nConst; i++){
    const Expr *pExpr = pConst->apExpr[i*2];
    assert( pExpr->op==TK_COLUMN );
    if( pExpr->iTable==pColumn->iTable
     && pExpr->iColumn==pColumn->iColumn
    ){
      return;  /* Already present.  Return without doing anything. */
    }
  }

  pConst->nConst++;
  pConst->apExpr = sqlite3DbReallocOrFree(pConst->pParse->db, pConst->apExpr,
                         pConst->nConst*2*sizeof(Expr*));
  if( pConst->apExpr==0 ){
    pConst->nConst = 0;
  }else{

    FROM A,
         (SELECT id,yy,zz FROM C) subq,
         B
   WHERE A.id='1'
     AND A.id=subq.yy
     AND B.id=subq.zz;
} {1}  

# 2018-10-25: Ticket [cf5ed20f]
# Incorrect join result with duplicate WHERE clause constraint.
#
do_execsql_test 400 {
  CREATE TABLE x(a, b, c);
  CREATE TABLE y(a, b);
  INSERT INTO x VALUES (1, 0, 1);
  INSERT INTO y VALUES (1, 2);
  SELECT x.a FROM x JOIN y ON x.c = y.a WHERE x.b = 1 AND x.b = 1;
} {}

finish_test