**     COPY
**     VACUUM
**     BEGIN TRANSACTION
**     COMMIT
**     ROLLBACK
**     PRAGMA
**
** $Id: build.c,v 1.118 2003/01/02 14:43:56 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** This routine is called when a new SQL statement is beginning to
** be parsed.  Check to see if the schema for the database needs
................................................................................
      sqliteVdbeAddOp(v, OP_AddImm, 1, 0);  /* Increment row count */
    }
    sqliteVdbeAddOp(v, OP_Goto, 0, addr);
    sqliteVdbeResolveLabel(v, end);
    sqliteVdbeAddOp(v, OP_Noop, 0, 0);
    sqliteEndWriteOperation(pParse);
    if( db->flags & SQLITE_CountRows ){
      sqliteVdbeAddOp(v, OP_ColumnCount, 1, 0);
      sqliteVdbeAddOp(v, OP_ColumnName, 0, 0);
      sqliteVdbeChangeP3(v, -1, "rows inserted", P3_STATIC);
      sqliteVdbeAddOp(v, OP_Callback, 1, 0);
    }
  }
  
copy_cleanup:
................................................................................
    static VdbeOp getCacheSize[] = {
      { OP_ReadCookie,  0, 2,        0},
      { OP_AbsValue,    0, 0,        0},
      { OP_Dup,         0, 0,        0},
      { OP_Integer,     0, 0,        0},
      { OP_Ne,          0, 6,        0},
      { OP_Integer,     MAX_PAGES,0, 0},
      { OP_ColumnCount, 1, 0,        0},
      { OP_ColumnName,  0, 0,        "cache_size"},
      { OP_Callback,    1, 0,        0},
    };
    Vdbe *v = sqliteGetVdbe(pParse);
    if( v==0 ) return;
    if( pRight->z==pLeft->z ){
      sqliteVdbeAddOpList(v, ArraySize(getCacheSize), getCacheSize);
................................................................................
  ** page cache size value.  It does not change the persistent
  ** cache size stored on the disk so the cache size will revert
  ** to its default value when the database is closed and reopened.
  ** N should be a positive integer.
  */
  if( sqliteStrICmp(zLeft,"cache_size")==0 ){
    static VdbeOp getCacheSize[] = {
      { OP_ColumnCount, 1, 0,        0},
      { OP_ColumnName,  0, 0,        "cache_size"},
      { OP_Callback,    1, 0,        0},
    };
    Vdbe *v = sqliteGetVdbe(pParse);
    if( v==0 ) return;
    if( pRight->z==pLeft->z ){
      int size = db->cache_size;;
................................................................................
  if( sqliteStrICmp(zLeft,"default_synchronous")==0 ){
    static VdbeOp getSync[] = {
      { OP_Integer,     0, 0,        0},
      { OP_ReadCookie,  0, 2,        0},
      { OP_Integer,     0, 0,        0},
      { OP_Lt,          0, 5,        0},
      { OP_AddImm,      1, 0,        0},
      { OP_ColumnCount, 1, 0,        0},
      { OP_ColumnName,  0, 0,        "synchronous"},
      { OP_Callback,    1, 0,        0},
    };
    Vdbe *v = sqliteGetVdbe(pParse);
    if( v==0 ) return;
    if( pRight->z==pLeft->z ){
      sqliteVdbeAddOpList(v, ArraySize(getSync), getSync);
................................................................................
  ** Return or set the local value of the synchronous flag.  Changing
  ** the local value does not make changes to the disk file and the
  ** default value will be restored the next time the database is
  ** opened.
  */
  if( sqliteStrICmp(zLeft,"synchronous")==0 ){
    static VdbeOp getSync[] = {
      { OP_ColumnCount, 1, 0,        0},
      { OP_ColumnName,  0, 0,        "synchronous"},
      { OP_Callback,    1, 0,        0},
    };
    Vdbe *v = sqliteGetVdbe(pParse);
    if( v==0 ) return;
    if( pRight->z==pLeft->z ){
      sqliteVdbeAddOp(v, OP_Integer, db->cache_size>=0, 0);
................................................................................
  if( sqliteStrICmp(zLeft, "table_info")==0 ){
    Table *pTab;
    Vdbe *v;
    pTab = sqliteFindTable(db, zRight);
    if( pTab ) v = sqliteGetVdbe(pParse);
    if( pTab && v ){
      static VdbeOp tableInfoPreface[] = {
        { OP_ColumnCount, 5, 0,       0},
        { OP_ColumnName,  0, 0,       "cid"},
        { OP_ColumnName,  1, 0,       "name"},
        { OP_ColumnName,  2, 0,       "type"},
        { OP_ColumnName,  3, 0,       "notnull"},
        { OP_ColumnName,  4, 0,       "dflt_value"},
      };
      int i;
................................................................................
    Index *pIdx;
    Table *pTab;
    Vdbe *v;
    pIdx = sqliteFindIndex(db, zRight);
    if( pIdx ) v = sqliteGetVdbe(pParse);
    if( pIdx && v ){
      static VdbeOp tableInfoPreface[] = {
        { OP_ColumnCount, 3, 0,       0},
        { OP_ColumnName,  0, 0,       "seqno"},
        { OP_ColumnName,  1, 0,       "cid"},
        { OP_ColumnName,  2, 0,       "name"},
      };
      int i;
      pTab = pIdx->pTable;
      sqliteVdbeAddOpList(v, ArraySize(tableInfoPreface), tableInfoPreface);
................................................................................
    if( pTab ){
      v = sqliteGetVdbe(pParse);
      pIdx = pTab->pIndex;
    }
    if( pTab && pIdx && v ){
      int i = 0; 
      static VdbeOp indexListPreface[] = {
        { OP_ColumnCount, 3, 0,       0},
        { OP_ColumnName,  0, 0,       "seq"},
        { OP_ColumnName,  1, 0,       "name"},
        { OP_ColumnName,  2, 0,       "unique"},
      };

      sqliteVdbeAddOpList(v, ArraySize(indexListPreface), indexListPreface);
      while(pIdx){
................................................................................
      { OP_SetInsert,   0, 0,        "2"},
      { OP_Open,        0, 2,        0},
      { OP_Rewind,      0, 6,        0},
      { OP_Column,      0, 3,        0},    /* 3 */
      { OP_SetInsert,   0, 0,        0},
      { OP_Next,        0, 3,        0},
      { OP_IntegrityCk, 0, 0,        0},    /* 6 */
      { OP_ColumnCount, 1, 0,        0},
      { OP_ColumnName,  0, 0,        "integrity_check"},
      { OP_Callback,    1, 0,        0},
      { OP_SetInsert,   1, 0,        "2"},
      { OP_OpenAux,     1, 2,        0},
      { OP_Rewind,      1, 16,       0},
      { OP_Column,      1, 3,        0},    /* 13 */
      { OP_SetInsert,   1, 0,        0},
      { OP_Next,        1, 13,       0},
      { OP_IntegrityCk, 1, 1,        0},    /* 16 */
      { OP_Callback,    1, 0,        0},
    };
    Vdbe *v = sqliteGetVdbe(pParse);
    if( v==0 ) return;
    sqliteVdbeAddOpList(v, ArraySize(checkDb), checkDb);
  }else

  {}
  sqliteFree(zLeft);
  sqliteFree(zRight);
}

**     COPY
**     VACUUM
**     BEGIN TRANSACTION
**     COMMIT
**     ROLLBACK
**     PRAGMA
**
** $Id: build.c,v 1.119 2003/01/11 13:30:57 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** This routine is called when a new SQL statement is beginning to
** be parsed.  Check to see if the schema for the database needs
................................................................................
      sqliteVdbeAddOp(v, OP_AddImm, 1, 0);  /* Increment row count */
    }
    sqliteVdbeAddOp(v, OP_Goto, 0, addr);
    sqliteVdbeResolveLabel(v, end);
    sqliteVdbeAddOp(v, OP_Noop, 0, 0);
    sqliteEndWriteOperation(pParse);
    if( db->flags & SQLITE_CountRows ){

      sqliteVdbeAddOp(v, OP_ColumnName, 0, 0);
      sqliteVdbeChangeP3(v, -1, "rows inserted", P3_STATIC);
      sqliteVdbeAddOp(v, OP_Callback, 1, 0);
    }
  }
  
copy_cleanup:
................................................................................
    static VdbeOp getCacheSize[] = {
      { OP_ReadCookie,  0, 2,        0},
      { OP_AbsValue,    0, 0,        0},
      { OP_Dup,         0, 0,        0},
      { OP_Integer,     0, 0,        0},
      { OP_Ne,          0, 6,        0},
      { OP_Integer,     MAX_PAGES,0, 0},

      { OP_ColumnName,  0, 0,        "cache_size"},
      { OP_Callback,    1, 0,        0},
    };
    Vdbe *v = sqliteGetVdbe(pParse);
    if( v==0 ) return;
    if( pRight->z==pLeft->z ){
      sqliteVdbeAddOpList(v, ArraySize(getCacheSize), getCacheSize);
................................................................................
  ** page cache size value.  It does not change the persistent
  ** cache size stored on the disk so the cache size will revert
  ** to its default value when the database is closed and reopened.
  ** N should be a positive integer.
  */
  if( sqliteStrICmp(zLeft,"cache_size")==0 ){
    static VdbeOp getCacheSize[] = {

      { OP_ColumnName,  0, 0,        "cache_size"},
      { OP_Callback,    1, 0,        0},
    };
    Vdbe *v = sqliteGetVdbe(pParse);
    if( v==0 ) return;
    if( pRight->z==pLeft->z ){
      int size = db->cache_size;;
................................................................................
  if( sqliteStrICmp(zLeft,"default_synchronous")==0 ){
    static VdbeOp getSync[] = {
      { OP_Integer,     0, 0,        0},
      { OP_ReadCookie,  0, 2,        0},
      { OP_Integer,     0, 0,        0},
      { OP_Lt,          0, 5,        0},
      { OP_AddImm,      1, 0,        0},

      { OP_ColumnName,  0, 0,        "synchronous"},
      { OP_Callback,    1, 0,        0},
    };
    Vdbe *v = sqliteGetVdbe(pParse);
    if( v==0 ) return;
    if( pRight->z==pLeft->z ){
      sqliteVdbeAddOpList(v, ArraySize(getSync), getSync);
................................................................................
  ** Return or set the local value of the synchronous flag.  Changing
  ** the local value does not make changes to the disk file and the
  ** default value will be restored the next time the database is
  ** opened.
  */
  if( sqliteStrICmp(zLeft,"synchronous")==0 ){
    static VdbeOp getSync[] = {

      { OP_ColumnName,  0, 0,        "synchronous"},
      { OP_Callback,    1, 0,        0},
    };
    Vdbe *v = sqliteGetVdbe(pParse);
    if( v==0 ) return;
    if( pRight->z==pLeft->z ){
      sqliteVdbeAddOp(v, OP_Integer, db->cache_size>=0, 0);
................................................................................
  if( sqliteStrICmp(zLeft, "table_info")==0 ){
    Table *pTab;
    Vdbe *v;
    pTab = sqliteFindTable(db, zRight);
    if( pTab ) v = sqliteGetVdbe(pParse);
    if( pTab && v ){
      static VdbeOp tableInfoPreface[] = {

        { OP_ColumnName,  0, 0,       "cid"},
        { OP_ColumnName,  1, 0,       "name"},
        { OP_ColumnName,  2, 0,       "type"},
        { OP_ColumnName,  3, 0,       "notnull"},
        { OP_ColumnName,  4, 0,       "dflt_value"},
      };
      int i;
................................................................................
    Index *pIdx;
    Table *pTab;
    Vdbe *v;
    pIdx = sqliteFindIndex(db, zRight);
    if( pIdx ) v = sqliteGetVdbe(pParse);
    if( pIdx && v ){
      static VdbeOp tableInfoPreface[] = {

        { OP_ColumnName,  0, 0,       "seqno"},
        { OP_ColumnName,  1, 0,       "cid"},
        { OP_ColumnName,  2, 0,       "name"},
      };
      int i;
      pTab = pIdx->pTable;
      sqliteVdbeAddOpList(v, ArraySize(tableInfoPreface), tableInfoPreface);
................................................................................
    if( pTab ){
      v = sqliteGetVdbe(pParse);
      pIdx = pTab->pIndex;
    }
    if( pTab && pIdx && v ){
      int i = 0; 
      static VdbeOp indexListPreface[] = {

        { OP_ColumnName,  0, 0,       "seq"},
        { OP_ColumnName,  1, 0,       "name"},
        { OP_ColumnName,  2, 0,       "unique"},
      };

      sqliteVdbeAddOpList(v, ArraySize(indexListPreface), indexListPreface);
      while(pIdx){
................................................................................
      { OP_SetInsert,   0, 0,        "2"},
      { OP_Open,        0, 2,        0},
      { OP_Rewind,      0, 6,        0},
      { OP_Column,      0, 3,        0},    /* 3 */
      { OP_SetInsert,   0, 0,        0},
      { OP_Next,        0, 3,        0},
      { OP_IntegrityCk, 0, 0,        0},    /* 6 */

      { OP_ColumnName,  0, 0,        "integrity_check"},
      { OP_Callback,    1, 0,        0},
      { OP_SetInsert,   1, 0,        "2"},
      { OP_OpenAux,     1, 2,        0},
      { OP_Rewind,      1, 15,       0},
      { OP_Column,      1, 3,        0},    /* 12 */
      { OP_SetInsert,   1, 0,        0},
      { OP_Next,        1, 12,       0},
      { OP_IntegrityCk, 1, 1,        0},    /* 15 */
      { OP_Callback,    1, 0,        0},
    };
    Vdbe *v = sqliteGetVdbe(pParse);
    if( v==0 ) return;
    sqliteVdbeAddOpList(v, ArraySize(checkDb), checkDb);
  }else

  {}
  sqliteFree(zLeft);
  sqliteFree(zRight);
}

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle DELETE FROM statements.
**
** $Id: delete.c,v 1.42 2002/09/14 13:47:32 drh Exp $
*/
#include "sqliteInt.h"


/*
** Given a table name, find the corresponding table and make sure the
** table is writeable.  Generate an error and return NULL if not.  If
................................................................................
  }
  sqliteEndWriteOperation(pParse);

  /*
  ** Return the number of rows that were deleted.
  */
  if( db->flags & SQLITE_CountRows ){
    sqliteVdbeAddOp(v, OP_ColumnCount, 1, 0);
    sqliteVdbeAddOp(v, OP_ColumnName, 0, 0);
    sqliteVdbeChangeP3(v, -1, "rows deleted", P3_STATIC);
    sqliteVdbeAddOp(v, OP_Callback, 1, 0);
  }

delete_from_cleanup:
  sqliteSrcListDelete(pTabList);

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle DELETE FROM statements.
**
** $Id: delete.c,v 1.43 2003/01/11 13:30:57 drh Exp $
*/
#include "sqliteInt.h"


/*
** Given a table name, find the corresponding table and make sure the
** table is writeable.  Generate an error and return NULL if not.  If
................................................................................
  }
  sqliteEndWriteOperation(pParse);

  /*
  ** Return the number of rows that were deleted.
  */
  if( db->flags & SQLITE_CountRows ){

    sqliteVdbeAddOp(v, OP_ColumnName, 0, 0);
    sqliteVdbeChangeP3(v, -1, "rows deleted", P3_STATIC);
    sqliteVdbeAddOp(v, OP_Callback, 1, 0);
  }

delete_from_cleanup:
  sqliteSrcListDelete(pTabList);

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle INSERT statements in SQLite.
**
** $Id: insert.c,v 1.67 2002/09/14 13:47:32 drh Exp $
*/
#include "sqliteInt.h"

/*
** This routine is call to handle SQL of the following forms:
**
**    insert into TABLE (IDLIST) values(EXPRLIST)
................................................................................

  sqliteEndWriteOperation(pParse);

  /*
  ** Return the number of rows inserted.
  */
  if( db->flags & SQLITE_CountRows ){
    sqliteVdbeAddOp(v, OP_ColumnCount, 1, 0);
    sqliteVdbeAddOp(v, OP_ColumnName, 0, 0);
    sqliteVdbeChangeP3(v, -1, "rows inserted", P3_STATIC);
    sqliteVdbeAddOp(v, OP_MemLoad, iCntMem, 0);
    sqliteVdbeAddOp(v, OP_Callback, 1, 0);
  }

insert_cleanup:

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle INSERT statements in SQLite.
**
** $Id: insert.c,v 1.68 2003/01/11 13:30:58 drh Exp $
*/
#include "sqliteInt.h"

/*
** This routine is call to handle SQL of the following forms:
**
**    insert into TABLE (IDLIST) values(EXPRLIST)
................................................................................

  sqliteEndWriteOperation(pParse);

  /*
  ** Return the number of rows inserted.
  */
  if( db->flags & SQLITE_CountRows ){

    sqliteVdbeAddOp(v, OP_ColumnName, 0, 0);
    sqliteVdbeChangeP3(v, -1, "rows inserted", P3_STATIC);
    sqliteVdbeAddOp(v, OP_MemLoad, iCntMem, 0);
    sqliteVdbeAddOp(v, OP_Callback, 1, 0);
  }

insert_cleanup:

** The pager is used to access a database disk file.  It implements
** atomic commit and rollback through the use of a journal file that
** is separate from the database file.  The pager also implements file
** locking to prevent two processes from writing the same database
** file simultaneously, or one process from reading the database while
** another is writing.
**
** @(#) $Id: pager.c,v 1.65 2003/01/07 14:46:08 drh Exp $
*/
#include "os.h"         /* Must be first to enable large file support */
#include "sqliteInt.h"
#include "pager.h"
#include <assert.h>
#include <string.h>

................................................................................
*/
#define PGHDR_TO_DATA(P)  ((void*)(&(P)[1]))
#define DATA_TO_PGHDR(D)  (&((PgHdr*)(D))[-1])
#define PGHDR_TO_EXTRA(P) ((void*)&((char*)(&(P)[1]))[SQLITE_PAGE_SIZE])

/*
** How big to make the hash table used for locating in-memory pages
** by page number.  Knuth says this should be a prime number.
*/
#define N_PG_HASH 2003






/*
** A open page cache is an instance of the following structure.
*/
struct Pager {
  char *zFilename;            /* Name of the database file */
  char *zJournal;             /* Name of the journal file */
................................................................................
*/
#ifdef SQLITE_TEST
int pager_old_format = 0;
#else
# define pager_old_format 0
#endif

/*
** Hash a page number
*/
#define pager_hash(PN)  ((PN)%N_PG_HASH)

/*
** Enable reference count tracking here:
*/
#ifdef SQLITE_TEST
  int pager_refinfo_enable = 0;
  static void pager_refinfo(PgHdr *p){
    static int cnt = 0;
................................................................................
}

/*
** Find a page in the hash table given its page number.  Return
** a pointer to the page or NULL if not found.
*/
static PgHdr *pager_lookup(Pager *pPager, Pgno pgno){
  PgHdr *p = pPager->aHash[pgno % N_PG_HASH];
  while( p && p->pgno!=pgno ){
    p = p->pNextHash;
  }
  return p;
}

/*
................................................................................
}

/*
** Increment the reference count for a page.  If the page is
** currently on the freelist (the reference count is zero) then
** remove it from the freelist.
*/

static void page_ref(PgHdr *pPg){
  if( pPg->nRef==0 ){
    /* The page is currently on the freelist.  Remove it. */
    if( pPg->pPrevFree ){
      pPg->pPrevFree->pNextFree = pPg->pNextFree;
    }else{
      pPg->pPager->pFirst = pPg->pNextFree;
    }
................................................................................
*/
int sqlitepager_get(Pager *pPager, Pgno pgno, void **ppPage){
  PgHdr *pPg;
  int rc;

  /* Make sure we have not hit any critical errors.
  */ 
  if( pPager==0 || pgno==0 ){
    return SQLITE_ERROR;
  }
  if( pPager->errMask & ~(PAGER_ERR_FULL) ){
    return pager_errcode(pPager);
  }

  /* If this is the first page accessed, then get a read lock
  ** on the database file.
  */
................................................................................
** in the page if the page is not already in cache.  This routine
** returns NULL if the page is not in cache or if a disk I/O error 
** has ever happened.
*/
void *sqlitepager_lookup(Pager *pPager, Pgno pgno){
  PgHdr *pPg;

  /* Make sure we have not hit any critical errors.
  */ 
  if( pPager==0 || pgno==0 ){
    return 0;
  }

  if( pPager->errMask & ~(PAGER_ERR_FULL) ){
    return 0;
  }
  if( pPager->nRef==0 ){
    return 0;
  }


  pPg = pager_lookup(pPager, pgno);
  if( pPg==0 ) return 0;
  page_ref(pPg);
  return PGHDR_TO_DATA(pPg);
}

/*

** The pager is used to access a database disk file.  It implements
** atomic commit and rollback through the use of a journal file that
** is separate from the database file.  The pager also implements file
** locking to prevent two processes from writing the same database
** file simultaneously, or one process from reading the database while
** another is writing.
**
** @(#) $Id: pager.c,v 1.66 2003/01/11 13:30:58 drh Exp $
*/
#include "os.h"         /* Must be first to enable large file support */
#include "sqliteInt.h"
#include "pager.h"
#include <assert.h>
#include <string.h>

................................................................................
*/
#define PGHDR_TO_DATA(P)  ((void*)(&(P)[1]))
#define DATA_TO_PGHDR(D)  (&((PgHdr*)(D))[-1])
#define PGHDR_TO_EXTRA(P) ((void*)&((char*)(&(P)[1]))[SQLITE_PAGE_SIZE])

/*
** How big to make the hash table used for locating in-memory pages
** by page number.
*/
#define N_PG_HASH 2048

/*
** Hash a page number
*/
#define pager_hash(PN)  ((PN)&(N_PG_HASH-1))

/*
** A open page cache is an instance of the following structure.
*/
struct Pager {
  char *zFilename;            /* Name of the database file */
  char *zJournal;             /* Name of the journal file */
................................................................................
*/
#ifdef SQLITE_TEST
int pager_old_format = 0;
#else
# define pager_old_format 0
#endif






/*
** Enable reference count tracking here:
*/
#ifdef SQLITE_TEST
  int pager_refinfo_enable = 0;
  static void pager_refinfo(PgHdr *p){
    static int cnt = 0;
................................................................................
}

/*
** Find a page in the hash table given its page number.  Return
** a pointer to the page or NULL if not found.
*/
static PgHdr *pager_lookup(Pager *pPager, Pgno pgno){
  PgHdr *p = pPager->aHash[pager_hash(pgno)];
  while( p && p->pgno!=pgno ){
    p = p->pNextHash;
  }
  return p;
}

/*
................................................................................
}

/*
** Increment the reference count for a page.  If the page is
** currently on the freelist (the reference count is zero) then
** remove it from the freelist.
*/
#define page_ref(P)   ((P)->nRef==0?_page_ref(P):(void)(P)->nRef++)
static void _page_ref(PgHdr *pPg){
  if( pPg->nRef==0 ){
    /* The page is currently on the freelist.  Remove it. */
    if( pPg->pPrevFree ){
      pPg->pPrevFree->pNextFree = pPg->pNextFree;
    }else{
      pPg->pPager->pFirst = pPg->pNextFree;
    }
................................................................................
*/
int sqlitepager_get(Pager *pPager, Pgno pgno, void **ppPage){
  PgHdr *pPg;
  int rc;

  /* Make sure we have not hit any critical errors.
  */ 
  assert( pPager!=0 );
  assert( pgno!=0 );

  if( pPager->errMask & ~(PAGER_ERR_FULL) ){
    return pager_errcode(pPager);
  }

  /* If this is the first page accessed, then get a read lock
  ** on the database file.
  */
................................................................................
** in the page if the page is not already in cache.  This routine
** returns NULL if the page is not in cache or if a disk I/O error 
** has ever happened.
*/
void *sqlitepager_lookup(Pager *pPager, Pgno pgno){
  PgHdr *pPg;

  assert( pPager!=0 );




  assert( pgno!=0 );
  if( pPager->errMask & ~(PAGER_ERR_FULL) ){
    return 0;
  }
  /* if( pPager->nRef==0 ){
  **  return 0;

  ** }
  */
  pPg = pager_lookup(pPager, pgno);
  if( pPg==0 ) return 0;
  page_ref(pPg);
  return PGHDR_TO_DATA(pPg);
}

/*

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle SELECT statements in SQLite.
**
** $Id: select.c,v 1.117 2002/12/03 02:34:50 drh Exp $
*/
#include "sqliteInt.h"


/*
** Allocate a new Select structure and return a pointer to that
** structure.
................................................................................
  SrcList *pTabList,  /* List of tables */
  ExprList *pEList    /* Expressions defining the result set */
){
  Vdbe *v = pParse->pVdbe;
  int i;
  if( pParse->colNamesSet || v==0 || sqlite_malloc_failed ) return;
  pParse->colNamesSet = 1;

  if( pParse->db->flags & SQLITE_ReportTypes ){
    sqliteVdbeAddOp(v, OP_ColumnCount, pEList->nExpr*2, 0);
  }else{
    sqliteVdbeAddOp(v, OP_ColumnCount, pEList->nExpr, 0);
  }

  for(i=0; i<pEList->nExpr; i++){
    Expr *p;
    char *zType = 0;
    int showFullNames;
    if( pEList->a[i].zName ){
      char *zName = pEList->a[i].zName;
      sqliteVdbeAddOp(v, OP_ColumnName, i, 0);

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle SELECT statements in SQLite.
**
** $Id: select.c,v 1.118 2003/01/11 13:30:58 drh Exp $
*/
#include "sqliteInt.h"


/*
** Allocate a new Select structure and return a pointer to that
** structure.
................................................................................
  SrcList *pTabList,  /* List of tables */
  ExprList *pEList    /* Expressions defining the result set */
){
  Vdbe *v = pParse->pVdbe;
  int i;
  if( pParse->colNamesSet || v==0 || sqlite_malloc_failed ) return;
  pParse->colNamesSet = 1;
#if 0
  if( pParse->db->flags & SQLITE_ReportTypes ){
    sqliteVdbeAddOp(v, OP_ColumnCount, pEList->nExpr*2, 0);
  }else{
    sqliteVdbeAddOp(v, OP_ColumnCount, pEList->nExpr, 0);
  }
#endif
  for(i=0; i<pEList->nExpr; i++){
    Expr *p;
    char *zType = 0;
    int showFullNames;
    if( pEList->a[i].zName ){
      char *zName = pEList->a[i].zName;
      sqliteVdbeAddOp(v, OP_ColumnName, i, 0);

**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** Internal interface definitions for SQLite.
**
** @(#) $Id: sqliteInt.h,v 1.151 2003/01/02 14:43:57 drh Exp $
*/
#include "config.h"
#include "sqlite.h"
#include "hash.h"
#include "vdbe.h"
#include "parse.h"
#include "btree.h"
................................................................................
  void *pArg;          /* First argument to the callback function */
  char *zErrMsg;       /* An error message */
  Token sErrToken;     /* The token at which the error occurred */
  Token sFirstToken;   /* The first token parsed */
  Token sLastToken;    /* The last token parsed */
  Table *pNewTable;    /* A table being constructed by CREATE TABLE */
  Vdbe *pVdbe;         /* An engine for executing database bytecode */
  u8 colNamesSet;      /* TRUE after OP_ColumnCount has been issued to pVdbe */
  u8 explain;          /* True if the EXPLAIN flag is found on the query */
  u8 initFlag;         /* True if reparsing CREATE TABLEs */
  u8 nameClash;        /* A permanent table name clashes with temp table name */
  u8 useAgg;           /* If true, extract field values from the aggregator
                       ** while generating expressions.  Normally false */
  u8 schemaVerified;   /* True if an OP_VerifySchema has been coded someplace
                       ** other than after an OP_Transaction */

**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** Internal interface definitions for SQLite.
**
** @(#) $Id: sqliteInt.h,v 1.152 2003/01/11 13:30:58 drh Exp $
*/
#include "config.h"
#include "sqlite.h"
#include "hash.h"
#include "vdbe.h"
#include "parse.h"
#include "btree.h"
................................................................................
  void *pArg;          /* First argument to the callback function */
  char *zErrMsg;       /* An error message */
  Token sErrToken;     /* The token at which the error occurred */
  Token sFirstToken;   /* The first token parsed */
  Token sLastToken;    /* The last token parsed */
  Table *pNewTable;    /* A table being constructed by CREATE TABLE */
  Vdbe *pVdbe;         /* An engine for executing database bytecode */
  u8 colNamesSet;      /* TRUE after OP_ColumnName has been issued to pVdbe */
  u8 explain;          /* True if the EXPLAIN flag is found on the query */
  u8 initFlag;         /* True if reparsing CREATE TABLEs */
  u8 nameClash;        /* A permanent table name clashes with temp table name */
  u8 useAgg;           /* If true, extract field values from the aggregator
                       ** while generating expressions.  Normally false */
  u8 schemaVerified;   /* True if an OP_VerifySchema has been coded someplace
                       ** other than after an OP_Transaction */

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle UPDATE statements.
**
** $Id: update.c,v 1.50 2002/09/14 13:47:32 drh Exp $
*/
#include "sqliteInt.h"

/*
** Process an UPDATE statement.
*/
void sqliteUpdate(
................................................................................

  sqliteEndWriteOperation(pParse);

  /*
  ** Return the number of rows that were changed.
  */
  if( db->flags & SQLITE_CountRows && !pParse->trigStack ){
    sqliteVdbeAddOp(v, OP_ColumnCount, 1, 0);
    sqliteVdbeAddOp(v, OP_ColumnName, 0, 0);
    sqliteVdbeChangeP3(v, -1, "rows updated", P3_STATIC);
    sqliteVdbeAddOp(v, OP_Callback, 1, 0);
  }

update_cleanup:
  sqliteFree(apIdx);
  sqliteFree(aXRef);
  sqliteSrcListDelete(pTabList);
  sqliteExprListDelete(pChanges);
  sqliteExprDelete(pWhere);
  return;
}

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle UPDATE statements.
**
** $Id: update.c,v 1.51 2003/01/11 13:30:58 drh Exp $
*/
#include "sqliteInt.h"

/*
** Process an UPDATE statement.
*/
void sqliteUpdate(
................................................................................

  sqliteEndWriteOperation(pParse);

  /*
  ** Return the number of rows that were changed.
  */
  if( db->flags & SQLITE_CountRows && !pParse->trigStack ){

    sqliteVdbeAddOp(v, OP_ColumnName, 0, 0);
    sqliteVdbeChangeP3(v, -1, "rows updated", P3_STATIC);
    sqliteVdbeAddOp(v, OP_Callback, 1, 0);
  }

update_cleanup:
  sqliteFree(apIdx);
  sqliteFree(aXRef);
  sqliteSrcListDelete(pTabList);
  sqliteExprListDelete(pChanges);
  sqliteExprDelete(pWhere);
  return;
}

**
** Various scripts scan this source file in order to generate HTML
** documentation, headers files, or other derived files.  The formatting
** of the code in this file is, therefore, important.  See other comments
** in this file for details.  If in doubt, do not deviate from existing
** commenting and indentation practices when changing or adding code.
**
** $Id: vdbe.c,v 1.194 2003/01/07 13:55:23 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** The makefile scans this source file and creates the following
** array of string constants which are the names of all VDBE opcodes.
................................................................................
    zStack[to] = aStack[to].z;
  }
  aStack[from].flags = 0;
  p->tos--;
  break;
}

/* Opcode: ColumnCount P1 * *
**
** Specify the number of column values that will appear in the
** array passed as the 4th parameter to the callback. 
*/
case OP_ColumnCount: {
  p->azColName[pOp->p1] = 0;
  p->nCallback = 0;
  break;
}

/* Opcode: ColumnName P1 * P3
**
** P3 becomes the P1-th column name (first is 0).  An array of pointers
** to all column names is passed as the 4th parameter to the callback.
*/
case OP_ColumnName: {
  p->azColName[pOp->p1] = pOp->p3;

**
** Various scripts scan this source file in order to generate HTML
** documentation, headers files, or other derived files.  The formatting
** of the code in this file is, therefore, important.  See other comments
** in this file for details.  If in doubt, do not deviate from existing
** commenting and indentation practices when changing or adding code.
**
** $Id: vdbe.c,v 1.195 2003/01/11 13:30:58 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** The makefile scans this source file and creates the following
** array of string constants which are the names of all VDBE opcodes.
................................................................................
    zStack[to] = aStack[to].z;
  }
  aStack[from].flags = 0;
  p->tos--;
  break;
}












/* Opcode: ColumnName P1 * P3
**
** P3 becomes the P1-th column name (first is 0).  An array of pointers
** to all column names is passed as the 4th parameter to the callback.
*/
case OP_ColumnName: {
  p->azColName[pOp->p1] = pOp->p3;