** for fast set membership tests. In this case an epheremal table must 
** be used unless <column> is an INTEGER PRIMARY KEY or an index can 
** be found with <column> as its left-most column.
**
** When the b-tree is being used for membership tests, the calling function
** needs to know whether or not the structure contains an SQL NULL 
** value in order to correctly evaluate expressions like "X IN (Y, Z)".
** If there is a chance that the b-tree might contain a NULL value at
** runtime, then a register is allocated and the register number written
** to *prNotFound. If there is no chance that the b-tree contains a
** NULL value, then *prNotFound is left unchanged.
**
** If a register is allocated and its location stored in *prNotFound, then
** its initial value is NULL. If the b-tree does not remain constant
** for the duration of the query (i.e. the SELECT that generates the b-tree
** is a correlated subquery) then the value of the allocated register is
** reset to NULL each time the b-tree is repopulated. This allows the
** caller to use vdbe code equivalent to the following:
**
**   if( register==NULL ){
**     has_null = <test if data structure contains null>
**     register = 1
**   }
**
................................................................................
  }
  sqlite3ExprCachePop(pParse, 1);

  return rReg;
}
#endif /* SQLITE_OMIT_SUBQUERY */



































































































































/*
** Duplicate an 8-byte value
*/
static char *dup8bytes(Vdbe *v, const char *in){
  char *out = sqlite3DbMallocRaw(sqlite3VdbeDb(v), 8);
  if( out ){
    memcpy(out, in, 8);
................................................................................
    case TK_SELECT: {
      testcase( op==TK_EXISTS );
      testcase( op==TK_SELECT );
      inReg = sqlite3CodeSubselect(pParse, pExpr, 0, 0);
      break;
    }
    case TK_IN: {
      int rNotFound = 0;
      int rMayHaveNull = 0;
      int j2, j3, j4, j5;
      char affinity;
      int eType;

      VdbeNoopComment((v, "begin IN expr r%d", target));
      eType = sqlite3FindInIndex(pParse, pExpr, &rMayHaveNull);
      if( rMayHaveNull ){
        rNotFound = ++pParse->nMem;
      }

      /* Figure out the affinity to use to create a key from the results
      ** of the expression. affinityStr stores a static string suitable for
      ** P4 of OP_MakeRecord.
      */
      affinity = comparisonAffinity(pExpr);


      /* Code the <expr> from "<expr> IN (...)". The temporary table
      ** pExpr->iTable contains the values that make up the (...) set.
      */
      sqlite3ExprCachePush(pParse);
      sqlite3ExprCode(pParse, pExpr->pLeft, target);
      j2 = sqlite3VdbeAddOp1(v, OP_IsNull, target);
      if( eType==IN_INDEX_ROWID ){
        j3 = sqlite3VdbeAddOp1(v, OP_MustBeInt, target);
        j4 = sqlite3VdbeAddOp3(v, OP_NotExists, pExpr->iTable, 0, target);
        sqlite3VdbeAddOp2(v, OP_Integer, 1, target);
        j5 = sqlite3VdbeAddOp0(v, OP_Goto);
        sqlite3VdbeJumpHere(v, j3);
        sqlite3VdbeJumpHere(v, j4);
        sqlite3VdbeAddOp2(v, OP_Integer, 0, target);
      }else{
        r2 = regFree2 = sqlite3GetTempReg(pParse);

        /* Create a record and test for set membership. If the set contains
        ** the value, then jump to the end of the test code. The target
        ** register still contains the true (1) value written to it earlier.
        */
        sqlite3VdbeAddOp4(v, OP_MakeRecord, target, 1, r2, &affinity, 1);

        sqlite3VdbeAddOp2(v, OP_Integer, 1, target);
        j5 = sqlite3VdbeAddOp3(v, OP_Found, pExpr->iTable, 0, r2);

        /* If the set membership test fails, then the result of the 
        ** "x IN (...)" expression must be either 0 or NULL. If the set
        ** contains no NULL values, then the result is 0. If the set 
        ** contains one or more NULL values, then the result of the
        ** expression is also NULL.
        */
        if( rNotFound==0 ){
          /* This branch runs if it is known at compile time (now) that 
          ** the set contains no NULL values. This happens as the result
          ** of a "NOT NULL" constraint in the database schema. No need
          ** to test the data structure at runtime in this case.
          */

          sqlite3VdbeAddOp2(v, OP_Integer, 0, target);
        }else{
          /* This block populates the rNotFound register with either NULL
          ** or 0 (an integer value). If the data structure contains one
          ** or more NULLs, then set rNotFound to NULL. Otherwise, set it
          ** to 0. If register rMayHaveNull is already set to some value
          ** other than NULL, then the test has already been run and 
          ** rNotFound is already populated.
          */
          static const char nullRecord[] = { 0x02, 0x00 };
          j3 = sqlite3VdbeAddOp1(v, OP_NotNull, rMayHaveNull);
          sqlite3VdbeAddOp2(v, OP_Null, 0, rNotFound);
          sqlite3VdbeAddOp4(v, OP_Blob, 2, rMayHaveNull, 0, 
                             nullRecord, P4_STATIC);
          j4 = sqlite3VdbeAddOp3(v, OP_Found, pExpr->iTable, 0, rMayHaveNull);
          sqlite3VdbeAddOp2(v, OP_Integer, 0, rNotFound);
          sqlite3VdbeJumpHere(v, j4);
          sqlite3VdbeJumpHere(v, j3);



          /* Copy the value of register rNotFound (which is either NULL or 0)
          ** into the target register. This will be the result of the
          ** expression.
          */
          sqlite3VdbeAddOp2(v, OP_Copy, rNotFound, target);

        }
      }
      sqlite3VdbeJumpHere(v, j2);
      sqlite3VdbeJumpHere(v, j5);
      sqlite3ExprCachePop(pParse, 1);
      VdbeComment((v, "end IN expr r%d", target));
      break;
    }
#endif
    /*
    **    x BETWEEN y AND z
    **
    ** This is equivalent to
    **
    **    x>=y AND x<=z
    **
................................................................................
      sqlite3VdbeAddOp2(v, op, r1, dest);
      testcase( regFree1==0 );
      break;
    }
    case TK_BETWEEN: {
      exprCodeBetween(pParse, pExpr, dest, 1, jumpIfNull);
      break;








    }
    default: {
      r1 = sqlite3ExprCodeTemp(pParse, pExpr, &regFree1);
      sqlite3VdbeAddOp3(v, OP_If, r1, dest, jumpIfNull!=0);
      testcase( regFree1==0 );
      testcase( jumpIfNull==0 );
      break;
................................................................................
      sqlite3VdbeAddOp2(v, op, r1, dest);
      testcase( regFree1==0 );
      break;
    }
    case TK_BETWEEN: {
      exprCodeBetween(pParse, pExpr, dest, 0, jumpIfNull);
      break;










    }
    default: {
      r1 = sqlite3ExprCodeTemp(pParse, pExpr, &regFree1);
      sqlite3VdbeAddOp3(v, OP_IfNot, r1, dest, jumpIfNull!=0);
      testcase( regFree1==0 );
      testcase( jumpIfNull==0 );
      break;

** for fast set membership tests. In this case an epheremal table must 
** be used unless <column> is an INTEGER PRIMARY KEY or an index can 
** be found with <column> as its left-most column.
**
** When the b-tree is being used for membership tests, the calling function
** needs to know whether or not the structure contains an SQL NULL 
** value in order to correctly evaluate expressions like "X IN (Y, Z)".
** If there is any chance that the (...) might contain a NULL value at
** runtime, then a register is allocated and the register number written
** to *prNotFound. If there is no chance that the (...) contains a
** NULL value, then *prNotFound is left unchanged.
**
** If a register is allocated and its location stored in *prNotFound, then
** its initial value is NULL.  If the (...) does not remain constant
** for the duration of the query (i.e. the SELECT within the (...)
** is a correlated subquery) then the value of the allocated register is
** reset to NULL each time the subquery is rerun. This allows the
** caller to use vdbe code equivalent to the following:
**
**   if( register==NULL ){
**     has_null = <test if data structure contains null>
**     register = 1
**   }
**
................................................................................
  }
  sqlite3ExprCachePop(pParse, 1);

  return rReg;
}
#endif /* SQLITE_OMIT_SUBQUERY */

#ifndef SQLITE_OMIT_SUBQUERY
/*
** Generate code for an IN expression.
**
**      x IN (SELECT ...)
**      x IN (value, value, ...)
**
** The left-hand side (LHS) is a scalar expression.  The right-hand side (RHS)
** is an array of zero or more values.  The expression is true if the LHS is
** contained within the RHS.  The value of the expression is unknown (NULL)
** if the LHS is NULL or if the LHS is not contained within the RHS and the
** RHS contains one or more NULL values.
**
** This routine generates code will jump to destIfFalse if the LHS is not 
** contained within the RHS.  If due to NULLs we cannot determine if the LHS
** is contained in the RHS then jump to destIfNull.  If the LHS is contained
** within the RHS then fall through.
*/
static void sqlite3ExprCodeIN(
  Parse *pParse,        /* Parsing and code generating context */
  Expr *pExpr,          /* The IN expression */
  int destIfFalse,      /* Jump here if LHS is not contained in the RHS */
  int destIfNull        /* Jump here if the results are unknown due to NULLs */
){
  int rRhsHasNull = 0;  /* Register that is true if RHS contains NULL values */
  char affinity;        /* Comparison affinity to use */
  int eType;            /* Type of the RHS */
  int r1;               /* Temporary use register */
  Vdbe *v;              /* Statement under construction */

  /* Compute the RHS.   After this step, the table with cursor
  ** pExpr->iTable will contains the values that make up the RHS.
  */
  v = pParse->pVdbe;
  assert( v!=0 );       /* OOM detected prior to this routine */
  VdbeNoopComment((v, "begin IN expr"));
  eType = sqlite3FindInIndex(pParse, pExpr, &rRhsHasNull);

  /* Figure out the affinity to use to create a key from the results
  ** of the expression. affinityStr stores a static string suitable for
  ** P4 of OP_MakeRecord.
  */
  affinity = comparisonAffinity(pExpr);

  /* Code the LHS, the <expr> from "<expr> IN (...)".
  */
  sqlite3ExprCachePush(pParse);
  r1 = sqlite3GetTempReg(pParse);
  sqlite3ExprCode(pParse, pExpr->pLeft, r1);
  sqlite3VdbeAddOp2(v, OP_IsNull, r1, destIfNull);


  if( eType==IN_INDEX_ROWID ){
    /* In this case, the RHS is the ROWID of table b-tree
    */
    sqlite3VdbeAddOp2(v, OP_MustBeInt, r1, destIfFalse);
    sqlite3VdbeAddOp3(v, OP_NotExists, pExpr->iTable, destIfFalse, r1);
  }else{
    /* In this case, the RHS is an index b-tree.
    */
    int r2;   /* Register holding LHS value as a Record */

    /* Create a record that can be used for membership testing.
    */
    r2 = sqlite3GetTempReg(pParse);
    sqlite3VdbeAddOp4(v, OP_MakeRecord, r1, 1, r2, &affinity, 1);

    /* If the set membership test fails, then the result of the 
    ** "x IN (...)" expression must be either 0 or NULL. If the set
    ** contains no NULL values, then the result is 0. If the set 
    ** contains one or more NULL values, then the result of the
    ** expression is also NULL.
    */
    if( rRhsHasNull==0 || destIfFalse==destIfNull ){
      /* This branch runs if it is known at compile time that the RHS
      ** cannot contain NULL values. This happens as the result
      ** of a "NOT NULL" constraint in the database schema.
      **
      ** Also run this branch if NULL is equivalent to FALSE
      ** for this particular IN operator.
      */
      sqlite3VdbeAddOp3(v, OP_NotFound, pExpr->iTable, destIfFalse, r2);

    }else{
      /* In this branch, the RHS of the IN might contain a NULL and
      ** the presence of a NULL on the RHS makes a difference in the
      ** outcome.
      */
      static const char nullRecord[] = { 0x02, 0x00 };
      int j1, j2, j3;

      /* First check to see if the LHS is contained in the RHS.  If so,
      ** then the presence of NULLs in the RHS does not matter, so jump
      ** over all of the code that follows.
      */
      j1 = sqlite3VdbeAddOp3(v, OP_Found, pExpr->iTable, 0, r2);

      /* Here we begin generating code that runs if the LHS is not
      ** contained within the RHS.  Generate additional code that
      ** tests the RHS for NULLs.  If the RHS contains a NULL then
      ** jump to destIfNull.  If there are no NULLs in the RHS then
      ** jump to destIfFalse.
      */
      j2 = sqlite3VdbeAddOp1(v, OP_NotNull, rRhsHasNull);
      sqlite3VdbeAddOp4(v, OP_Blob, 2, r2, 0, nullRecord, P4_STATIC);
      j3 = sqlite3VdbeAddOp3(v, OP_Found, pExpr->iTable, 0, r2);
      sqlite3VdbeAddOp2(v, OP_Integer, -1, rRhsHasNull);
      sqlite3VdbeJumpHere(v, j3);
      sqlite3VdbeAddOp2(v, OP_AddImm, rRhsHasNull, 1);
      sqlite3VdbeJumpHere(v, j2);

      /* Jump to the appropriate target depending on whether or not
      ** the RHS contains a NULL
      */
      sqlite3VdbeAddOp2(v, OP_If, rRhsHasNull, destIfNull);
      sqlite3VdbeAddOp2(v, OP_Goto, 0, destIfFalse);

      /* The OP_Found at the top of this branch jumps here when true, 
      ** causing the overall IN expression evaluation to fall through.
      */
      sqlite3VdbeJumpHere(v, j1);
    }
    sqlite3ReleaseTempReg(pParse, r2);
  }
  sqlite3ReleaseTempReg(pParse, r1);
  sqlite3ExprCachePop(pParse, 1);
  VdbeComment((v, "end IN expr"));
}
#endif /* SQLITE_OMIT_SUBQUERY */

/*
** Duplicate an 8-byte value
*/
static char *dup8bytes(Vdbe *v, const char *in){
  char *out = sqlite3DbMallocRaw(sqlite3VdbeDb(v), 8);
  if( out ){
    memcpy(out, in, 8);
................................................................................
    case TK_SELECT: {
      testcase( op==TK_EXISTS );
      testcase( op==TK_SELECT );
      inReg = sqlite3CodeSubselect(pParse, pExpr, 0, 0);
      break;
    }
    case TK_IN: {
      int destIfFalse = sqlite3VdbeMakeLabel(v);




























      int destIfNull = sqlite3VdbeMakeLabel(v);


      sqlite3VdbeAddOp2(v, OP_Null, 0, target);








      sqlite3ExprCodeIN(pParse, pExpr, destIfFalse, destIfNull);
      sqlite3VdbeAddOp2(v, OP_Integer, 1, target);














      sqlite3VdbeResolveLabel(v, destIfFalse);
      sqlite3VdbeAddOp2(v, OP_AddImm, target, 0);

















      sqlite3VdbeResolveLabel(v, destIfNull);
      break;
    }





#endif /* SQLITE_OMIT_SUBQUERY */









    /*
    **    x BETWEEN y AND z
    **
    ** This is equivalent to
    **
    **    x>=y AND x<=z
    **
................................................................................
      sqlite3VdbeAddOp2(v, op, r1, dest);
      testcase( regFree1==0 );
      break;
    }
    case TK_BETWEEN: {
      exprCodeBetween(pParse, pExpr, dest, 1, jumpIfNull);
      break;
    }
    case TK_IN: {
      int destIfFalse = sqlite3VdbeMakeLabel(v);
      int destIfNull = jumpIfNull ? dest : destIfFalse;
      sqlite3ExprCodeIN(pParse, pExpr, destIfFalse, destIfNull);
      sqlite3VdbeAddOp2(v, OP_Goto, 0, dest);
      sqlite3VdbeResolveLabel(v, destIfFalse);
      break;
    }
    default: {
      r1 = sqlite3ExprCodeTemp(pParse, pExpr, &regFree1);
      sqlite3VdbeAddOp3(v, OP_If, r1, dest, jumpIfNull!=0);
      testcase( regFree1==0 );
      testcase( jumpIfNull==0 );
      break;
................................................................................
      sqlite3VdbeAddOp2(v, op, r1, dest);
      testcase( regFree1==0 );
      break;
    }
    case TK_BETWEEN: {
      exprCodeBetween(pParse, pExpr, dest, 0, jumpIfNull);
      break;
    }
    case TK_IN: {
      if( jumpIfNull ){
        sqlite3ExprCodeIN(pParse, pExpr, dest, dest);
      }else{
        int destIfNull = sqlite3VdbeMakeLabel(v);
        sqlite3ExprCodeIN(pParse, pExpr, dest, destIfNull);
        sqlite3VdbeResolveLabel(v, destIfNull);
      }
      break;
    }
    default: {
      r1 = sqlite3ExprCodeTemp(pParse, pExpr, &regFree1);
      sqlite3VdbeAddOp3(v, OP_IfNot, r1, dest, jumpIfNull!=0);
      testcase( regFree1==0 );
      testcase( jumpIfNull==0 );
      break;

  break;
}
  

/* Opcode: Found P1 P2 P3 * *
**
** Register P3 holds a blob constructed by MakeRecord.  P1 is an index.
** If an entry that matches the value in register p3 exists in P1 then
** jump to P2.  If the P3 value does not match any entry in P1
** then fall thru.  The P1 cursor is left pointing at the matching entry
** if it exists.
**
** This instruction is used to implement the IN operator where the
** left-hand side is a SELECT statement.  P1 may be a true index, or it
** may be a temporary index that holds the results of the SELECT
** statement.   This instruction is also used to implement the
** DISTINCT keyword in SELECT statements.
**
** This instruction checks if index P1 contains a record for which 
** the first N serialized values exactly match the N serialized values
** in the record in register P3, where N is the total number of values in
** the P3 record (the P3 record is a prefix of the P1 record). 
**
** See also: NotFound, IsUnique, NotExists
*/
/* Opcode: NotFound P1 P2 P3 * *
**
** Register P3 holds a blob constructed by MakeRecord.  P1 is
** an index.  If no entry exists in P1 that matches the blob then jump
** to P2.  If an entry does existing, fall through.  The cursor is left
** pointing to the entry that matches.

**
** See also: Found, NotExists, IsUnique
*/
case OP_NotFound:       /* jump, in3 */
case OP_Found: {        /* jump, in3 */
  int alreadyExists;
  VdbeCursor *pC;
................................................................................
    assert( pIn3->flags & MEM_Blob );
    ExpandBlob(pIn3);
    pIdxKey = sqlite3VdbeRecordUnpack(pC->pKeyInfo, pIn3->n, pIn3->z,
                                      aTempRec, sizeof(aTempRec));
    if( pIdxKey==0 ){
      goto no_mem;
    }
    if( pOp->opcode==OP_Found ){
      pIdxKey->flags |= UNPACKED_PREFIX_MATCH;
    }
    rc = sqlite3BtreeMovetoUnpacked(pC->pCursor, pIdxKey, 0, 0, &res);
    sqlite3VdbeDeleteUnpackedRecord(pIdxKey);
    if( rc!=SQLITE_OK ){
      break;
    }
    alreadyExists = (res==0);
    pC->deferredMoveto = 0;

  break;
}
  

/* Opcode: Found P1 P2 P3 * *
**
** Register P3 holds a blob constructed by MakeRecord.  P1 is an index.
** If P3 is a prefix of any entry in P1 then a jump is made to P2 and

** P1 is left pointing at the matching entry.














*/
/* Opcode: NotFound P1 P2 P3 * *
**
** Register P3 holds a blob constructed by MakeRecord.  P1 is
** an index.  If P3 is not the prefix of any entry in P1 then a jump
** is made to P2.  If P1 does contain an entry whose prefix matches
** P3 then control falls through to the next instruction and P1 is
** left pointing at the matching entry.
**
** See also: Found, NotExists, IsUnique
*/
case OP_NotFound:       /* jump, in3 */
case OP_Found: {        /* jump, in3 */
  int alreadyExists;
  VdbeCursor *pC;
................................................................................
    assert( pIn3->flags & MEM_Blob );
    ExpandBlob(pIn3);
    pIdxKey = sqlite3VdbeRecordUnpack(pC->pKeyInfo, pIn3->n, pIn3->z,
                                      aTempRec, sizeof(aTempRec));
    if( pIdxKey==0 ){
      goto no_mem;
    }

    pIdxKey->flags |= UNPACKED_PREFIX_MATCH;

    rc = sqlite3BtreeMovetoUnpacked(pC->pCursor, pIdxKey, 0, 0, &res);
    sqlite3VdbeDeleteUnpackedRecord(pIdxKey);
    if( rc!=SQLITE_OK ){
      break;
    }
    alreadyExists = (res==0);
    pC->deferredMoveto = 0;