SQLite

            break;
          }
        }
        if( j>0 && sqlite3IsIdChar(z[j-1]) && sqlite3IsIdChar(zSql[i]) ){
          z[j++] = ' ';
        }
        if( tokenType==TK_ID ){
          if( zSql[i]=='"'
           && sqlite3VdbeUsesDoubleQuotedString(db,pVdbe,zSql+i,n)
          ){
            z[j++] = '?';
            break;
          }
          if( nParen==nParenAtIN ) iStartIN = 0;

        }
        copyNormalizedToken(zSql, i, n, flags, z, &j);
        break;
      }
    }
  }
  assert( j<nZ && "one" );

      **
      ** Someday, I hope to get rid of this hack. Unfortunately there is
      ** a huge amount of legacy SQL that uses it. So for now, we just
      ** issue a warning.
      */
      sqlite3_log(SQLITE_WARNING,
        "double-quoted string literal: \"%w\"", zCol);
#ifdef SQLITE_ENABLE_NORMALIZE
      sqlite3VdbeAddDblquoteStr(db,pParse->pVdbe, zCol);
#endif
      pExpr->op = TK_STRING;
      pExpr->y.pTab = 0;
      return WRC_Prune;
    }
    if( sqlite3ExprIdToTrueFalse(pExpr) ){
      return WRC_Prune;
    }

int sqlite3VdbeReset(Vdbe*);
void sqlite3VdbeSetNumCols(Vdbe*,int);
int sqlite3VdbeSetColName(Vdbe*, int, int, const char *, void(*)(void*));
void sqlite3VdbeCountChanges(Vdbe*);
sqlite3 *sqlite3VdbeDb(Vdbe*);
u8 sqlite3VdbePrepareFlags(Vdbe*);
void sqlite3VdbeSetSql(Vdbe*, const char *z, int n, u8);
#ifdef SQLITE_ENABLE_NORMALIZE
void sqlite3VdbeAddDblquoteStr(sqlite3*,Vdbe*,const char*);
int sqlite3VdbeUsesDoubleQuotedString(sqlite3*,Vdbe*,const char*,int);
#endif
void sqlite3VdbeSwap(Vdbe*,Vdbe*);
VdbeOp *sqlite3VdbeTakeOpArray(Vdbe*, int*, int*);
sqlite3_value *sqlite3VdbeGetBoundValue(Vdbe*, int, u8);
void sqlite3VdbeSetVarmask(Vdbe*, int);
#ifndef SQLITE_OMIT_TRACE
  char *sqlite3VdbeExpandSql(Vdbe*, const char*);
#endif

};

/* A bitfield type for use inside of structures.  Always follow with :N where
** N is the number of bits.
*/
typedef unsigned bft;  /* Bit Field Type */

/* The ScanStatus object holds a single value for the
** sqlite3_stmt_scanstatus() interface.
*/
typedef struct ScanStatus ScanStatus;
struct ScanStatus {
  int addrExplain;                /* OP_Explain for loop */
  int addrLoop;                   /* Address of "loops" counter */
  int addrVisit;                  /* Address of "rows visited" counter */
  int iSelectID;                  /* The "Select-ID" for this loop */
  LogEst nEst;                    /* Estimated output rows per loop */
  char *zName;                    /* Name of table or index */
};

/* The DblquoteStr object holds the text of a double-quoted
** string for a prepared statement.  A linked list of these objects
** is constructed during statement parsing and is held on Vdbe.pDblStr.
** When computing a normalized SQL statement for an SQL statement, that
** list is consulted for each double-quoted identifier to see if the
** identifier should really be a string literal.
*/
typedef struct DblquoteStr DblquoteStr;
struct DblquoteStr {
  DblquoteStr *pNextStr;   /* Next string literal in the list */
  char z[8];               /* Dequoted value for the string */
};

/*
** An instance of the virtual machine.  This structure contains the complete
** state of the virtual machine.
**
** The "sqlite3_stmt" structure pointer that is returned by sqlite3_prepare()
** is really a pointer to an instance of this structure.
*/
struct Vdbe {
  sqlite3 *db;            /* The database connection that owns this statement */
  Vdbe *pPrev,*pNext;     /* Linked list of VDBEs with the same Vdbe.db */
  Parse *pParse;          /* Parsing context used to create this Vdbe */
  ynVar nVar;             /* Number of entries in aVar[] */
  u32 magic;              /* Magic number for sanity checking */
  int nMem;               /* Number of memory locations currently allocated */
  int nCursor;            /* Number of slots in apCsr[] */
  u32 cacheCtr;           /* VdbeCursor row cache generation counter */
  int pc;                 /* The program counter */
  int rc;                 /* Value to return */
  int nChange;            /* Number of db changes made since last reset */
  int iStatement;         /* Statement number (or 0 if has no opened stmt) */
  i64 iCurrentTime;       /* Value of julianday('now') for this statement */
  i64 nFkConstraint;      /* Number of imm. FK constraints this VM */
  i64 nStmtDefCons;       /* Number of def. constraints when stmt started */
  i64 nStmtDefImmCons;    /* Number of def. imm constraints when stmt started */

  /* When allocating a new Vdbe object, all of the fields below should be
  ** initialized to zero or NULL */

  bft bIsReader:1;        /* True for statements that read */
  yDbMask btreeMask;      /* Bitmask of db->aDb[] entries referenced */
  yDbMask lockMask;       /* Subset of btreeMask that requires a lock */
  u32 aCounter[7];        /* Counters used by sqlite3_stmt_status() */
  char *zSql;             /* Text of the SQL statement that generated this */
#ifdef SQLITE_ENABLE_NORMALIZE
  char *zNormSql;         /* Normalization of the associated SQL statement */
  DblquoteStr *pDblStr;   /* List of double-quoted string literals */
#endif
  void *pFree;            /* Free this when deleting the vdbe */
  VdbeFrame *pFrame;      /* Parent frame */
  VdbeFrame *pDelFrame;   /* List of frame objects to free on VM reset */
  int nFrame;             /* Number of frames in pFrame list */
  u32 expmask;            /* Binding to these vars invalidates VM */
  SubProgram *pProgram;   /* Linked list of all sub-programs used by VM */

  if( p->zSql && (prepFlags & SQLITE_PREPARE_NORMALIZE)!=0 ){
    p->zNormSql = sqlite3Normalize(p, p->zSql, n);
    assert( p->zNormSql!=0 || p->db->mallocFailed );
  }
#endif
}

#ifdef SQLITE_ENABLE_NORMALIZE
/*
** Add a new element to the Vdbe->pDblStr list.
*/
void sqlite3VdbeAddDblquoteStr(sqlite3 *db, Vdbe *p, const char *z){
  if( p ){
    int n = sqlite3Strlen30(z);
    DblquoteStr *pStr = sqlite3DbMallocRawNN(db,
                            sizeof(*pStr)+n+1-sizeof(pStr->z));
    if( pStr ){
      pStr->pNextStr = p->pDblStr;
      p->pDblStr = pStr;
      memcpy(pStr->z, z, n+1);
    }
  }
}
#endif

#ifdef SQLITE_ENABLE_NORMALIZE
/*
** zId of length nId is a double-quoted identifier.  Check to see if
** that identifier is really used as a string literal.
*/
int sqlite3VdbeUsesDoubleQuotedString(
  sqlite3 *db,            /* Used for transient malloc */
  Vdbe *pVdbe,            /* The prepared statement */
  const char *zId,        /* The double-quoted identifier */
  int nId                 /* Bytes in zId, which is not zero-terminated */
){
  char *z;
  DblquoteStr *pStr;
  assert( zId!=0 );
  assert( zId[0]=='"' );
  assert( nId>=2 );
  assert( zId[nId-1]=='"' );
  if( pVdbe->pDblStr==0 ) return 0;
  z = sqlite3DbStrNDup(db, zId, nId);
  if( z==0 ) return 0;
  sqlite3Dequote(z);
  for(pStr=pVdbe->pDblStr; pStr; pStr=pStr->pNextStr){
    if( strcmp(z, pStr->z)==0 ) break;
  }
  sqlite3DbFree(db, z);
  return pStr!=0;
}
#endif

/*
** Swap all content between two VDBE structures.
*/
void sqlite3VdbeSwap(Vdbe *pA, Vdbe *pB){
  Vdbe tmp, *pTmp;
  char *zTmp;
  assert( pA->db==pB->db );
  tmp = *pA;
  *pA = *pB;
  *pB = tmp;
  pTmp = pA->pNext;
  pA->pNext = pB->pNext;
  pB->pNext = pTmp;
  pTmp = pA->pPrev;
  pA->pPrev = pB->pPrev;
  pB->pPrev = pTmp;
  zTmp = pA->zSql;
  pA->zSql = pB->zSql;
  pB->zSql = zTmp;
#if 0
  zTmp = pA->zNormSql;
  pA->zNormSql = pB->zNormSql;
  pB->zNormSql = zTmp;
#endif
  pB->expmask = pA->expmask;
  pB->prepFlags = pA->prepFlags;
  memcpy(pB->aCounter, pA->aCounter, sizeof(pB->aCounter));

    sqlite3DbFree(db, p->pFree);
  }
  vdbeFreeOpArray(db, p->aOp, p->nOp);
  sqlite3DbFree(db, p->aColName);
  sqlite3DbFree(db, p->zSql);
#ifdef SQLITE_ENABLE_NORMALIZE
  sqlite3DbFree(db, p->zNormSql);
  {
    DblquoteStr *pThis, *pNext;
    for(pThis=p->pDblStr; pThis; pThis=pNext){
      pNext = pThis->pNextStr;
      sqlite3DbFree(db, pThis);
    }
  }
#endif
#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
  {
    int i;
    for(i=0; i<p->nScan; i++){
      sqlite3DbFree(db, p->aScan[i].zName);
    }

  {SELECT a FROM t1 WHERE x IN (1,2,3) AND hex8('abc');}
  0x2
  {0 {SELECT a FROM t1 WHERE x IN(?,?,?)AND hex8(?);}}

  430
  {SELECT "a" FROM t1 WHERE "x" IN ("1","2",'3');}
  0x2
  {0 {SELECT"a"FROM t1 WHERE"x"IN(?,?,?);}}

  440
  {SELECT 'a' FROM t1 WHERE 'x';}
  0x2
  {0 {SELECT?FROM t1 WHERE?;}}

  450