SQLite

** Author contact information:
**   drh@hwaci.com
**   http://www.hwaci.com/drh/
**
*************************************************************************
** This file contains C code routines that are called by the parser
** when syntax rules are reduced.  The routines in this file handle
** the following kinds of syntax:
**
**     CREATE TABLE
**     DROP TABLE
**     CREATE INDEX
**     DROP INDEX
**     creating expressions and ID lists
**     COPY
**     VACUUM
**
** $Id: build.c,v 1.18 2000/06/17 13:12:39 drh Exp $
*/
#include "sqliteInt.h"

/*
** This routine is called after a single SQL statement has been
** parsed and we want to execute the VDBE code to implement 
** that statement.  Prior action routines should have already
** constructed VDBE code to do the work of the SQL statement.
** This routine just has to execute the VDBE code.
**
** Note that if an error occurred, it might be the case that
** no VDBE code was generated.
*/
void sqliteExec(Parse *pParse){

    if( sqliteStrICmp(pTable->zName, zName)==0 ) return pTable;
  }
  return 0;
}

/*
** Locate the in-memory structure that describes the
** format of a particular index given the name
** of that index.  Return NULL if not found.
*/
Index *sqliteFindIndex(sqlite *db, char *zName){
  Index *p;
  int h;

  h = sqliteHashNoCase(zName, 0) % N_HASH;
  for(p=db->apIdxHash[h]; p; p=p->pHash){

  }
  sqliteFree(pTable->zName);
  sqliteFree(pTable->aCol);
  sqliteFree(pTable);
}

/*
** Construct the name of a user table or index from a token.
**
** Space to hold the name is obtained from sqliteMalloc() and must
** be freed by the calling function.
*/
char *sqliteTableNameFromToken(Token *pName){
  char *zName = sqliteStrNDup(pName->z, pName->n);
  sqliteDequote(zName);

/*
** This routine is called to report the final ")" that terminates
** a CREATE TABLE statement.
**
** The table structure is added to the internal hash tables.  
**
** An entry for the table is made in the master table on disk,
** unless initFlag==1.  When initFlag==1, it means we are reading
** the master table because we just connected to the database, so 
** the entry for this table already exists in the master table.
** We do not want to create it again.
*/
void sqliteEndTable(Parse *pParse, Token *pEnd){
  Table *p;
  int h;

  if( pTable->readOnly ){
    sqliteSetString(&pParse->zErrMsg, "table ", pTable->zName, 
       " may not be dropped", 0);
    pParse->nErr++;
    return;
  }

  /* Generate code to remove the table from the master table
  ** on disk.
  */
  v = sqliteGetVdbe(pParse);
  if( v ){
    static VdbeOp dropTable[] = {
      { OP_Open,       0, 1,        MASTER_NAME },
      { OP_ListOpen,   0, 0,        0},
      { OP_String,     0, 0,        0}, /* 2 */
      { OP_Next,       0, ADDR(10), 0}, /* 3 */

    sqliteVdbeChangeP3(v, base+2, pTable->zName, 0);
    sqliteVdbeChangeP3(v, base+14, pTable->zName, 0);
    for(pIdx=pTable->pIndex; pIdx; pIdx=pIdx->pNext){
      sqliteVdbeAddOp(v, OP_Destroy, 0, 0, pIdx->zName, 0);
    }
  }

  /* Remove the in-memory table structure and free its memory.
  **
  ** Exception: if the SQL statement began with the EXPLAIN keyword,
  ** then no changes are made.
  */
  if( !pParse->explain ){
    h = sqliteHashNoCase(pTable->zName, 0) % N_HASH;
    if( pParse->db->apTblHash[h]==pTable ){

/*
** Create a new index for an SQL table.  pIndex is the name of the index 
** and pTable is the name of the table that is to be indexed.  Both will 
** be NULL for a primary key.  In that case, use pParse->pNewTable as the 
** table to be indexed.
**
** pList is a list of columns to be indexed.  pList will be NULL if the
** most recently added column of the table is labeled as the primary key.
*/
void sqliteCreateIndex(
  Parse *pParse,   /* All information about this parse */
  Token *pName,    /* Name of the index.  May be NULL */
  Token *pTable,   /* Name of the table to index.  Use pParse->pNewTable if 0 */
  IdList *pList,   /* A list of columns to be indexed */
  Token *pStart,   /* The CREATE token that begins a CREATE TABLE statement */
  Token *pEnd      /* The ")" that closes the CREATE INDEX statement */
){
  Table *pTab;     /* Table to be indexed */
  Index *pIndex;   /* The index to be created */
  char *zName = 0;
  int i, j, h;

    sqliteSetString(&pParse->zErrMsg, "there is already a table named ",
       zName, 0);
    pParse->nErr++;
    goto exit_create_index;
  }

  /* If pList==0, it means this routine was called to make a primary
  ** key out of the last column added to the table under construction.
  ** So create a fake list to simulate this.
  */
  if( pList==0 ){
    nullId.z = pTab->aCol[pTab->nCol-1].zName;
    nullId.n = strlen(nullId.z);
    pList = sqliteIdListAppend(0, &nullId);
    if( pList==0 ) goto exit_create_index;

  }
  pIndex->aiField = (int*)&pIndex[1];
  pIndex->zName = (char*)&pIndex->aiField[pList->nId];
  strcpy(pIndex->zName, zName);
  pIndex->pTable = pTab;
  pIndex->nField = pList->nId;

  /* Scan the names of the columns of the table to be indexed and
  ** load the column indices into the Index structure.  Report an error
  ** if any column is not found.
  */
  for(i=0; i<pList->nId; i++){
    for(j=0; j<pTab->nCol; j++){
      if( sqliteStrICmp(pList->a[i].zName, pTab->aCol[j].zName)==0 ) break;
    }
    if( j>=pTab->nCol ){
      sqliteSetString(&pParse->zErrMsg, "table ", pTab->zName, 
        " has no column named ", pList->a[i].zName, 0);
      pParse->nErr++;
      sqliteFree(pIndex);
      goto exit_create_index;
    }
    pIndex->aiField[i] = j;
  }

** Boston, MA  02111-1307, USA.
**
** Author contact information:
**   drh@hwaci.com
**   http://www.hwaci.com/drh/
**
*************************************************************************
** This file contains code to implement the database backend (DBBE)
** for sqlite.  The database backend is the interface between
** sqlite and the code that does the actually reading and writing
** of information to the disk.
**
** This file uses GDBM as the database backend.  It should be
** relatively simple to convert to a different database such
** as NDBM, SDBM, or BerkeleyDB.
**
** $Id: dbbe.c,v 1.14 2000/06/17 13:12:39 drh Exp $
*/
#include "sqliteInt.h"
#include <gdbm.h>
#include <sys/stat.h>
#include <unistd.h>
#include <ctype.h>
#include <time.h>

/*
** Information about each open disk file is an instance of this 
** structure.  There will only be one such structure for each
** disk file.  If the VDBE opens the same file twice (as will happen
** for a self-join, for example) then two DbbeTable structures are
** created but there is only a single BeFile structure with an
** nRef of 2.
*/
typedef struct BeFile BeFile;
struct BeFile {
  char *zName;            /* Name of the file */
  GDBM_FILE dbf;          /* The file itself */
  int nRef;               /* Number of references */
  int delOnClose;         /* Delete when closing */
  int writeable;          /* Opened for writing */
  BeFile *pNext, *pPrev;  /* Next and previous on list of open files */
};

/*
** The following structure holds the current state of the RC4 algorithm.
** We use RC4 as a random number generator.  Each call to RC4 gives
** a random 8-bit number.
**
** Nothing in this file or anywhere else in SQLite does any kind of
** encryption.  The RC4 algorithm is being used as a PRNG (pseudo-random
** number generator) not as an encryption device.
*/
struct rc4 {
  int i, j;
  int s[256];
};

/*
** The complete database is an instance of the following structure.
*/
struct Dbbe {
  char *zDir;        /* The directory containing the database */
  int write;         /* True for write permission */
  BeFile *pOpen;     /* List of open files */
  int nTemp;         /* Number of temporary files created */
  FILE **apTemp;     /* Space to hold temporary file pointers */
  char **azTemp;     /* Names of the temporary files */
  struct rc4 rc4;    /* The random number generator */
};

/*
** An cursor into a database file is an instance of the following structure.
** There can only be a single BeFile structure for each disk file, but
** there can be multiple DbbeTable structures.  Each DbbeTable represents
** a cursor pointing to a particular part of the open BeFile.  The
** BeFile.nRef field hold a count of the number of DbbeTable structures
** associated with the same disk file.
*/
struct DbbeTable {
  Dbbe *pBe;         /* The database of which this record is a part */
  BeFile *pFile;     /* The database file for this table */
  datum key;         /* Most recently used key */
  datum data;        /* Most recent data */
  int needRewind;    /* Next key should be the first */
  int readPending;   /* The fetch hasn't actually been done yet */
};

/*
** Initialize the RC4 PRNG.  "seed" is a pointer to some random
** data used to initialize the PRNG.  
*/
static void rc4init(struct rc4 *p, char *seed, int seedlen){
  int i;
  char k[256];
  p->j = 0;
  p->i = 0;
  for(i=0; i<256; i++){
    p->s[i] = i;
    k[i] = seed[i%seedlen];
  }
  for(i=0; i<256; i++){
    int t;
    p->j = (p->j + p->s[i] + k[i]) & 0xff;
    t = p->s[p->j];
    p->s[p->j] = p->s[i];
    p->s[i] = t;
  }
}

/*
** Get a single 8-bit random value from the RC4 PRNG.
*/
static int rc4byte(struct rc4 *p){
  int t;
  p->i = (p->i + 1) & 0xff;
  p->j = (p->j + p->s[p->i]) & 0xff;
  t = p->s[p->i];
  p->s[p->i] = p->s[p->j];

      zFile[i] = '+';
    }
  }
  return zFile;
}

/*
** Generate a random filename with the given prefix.  The new filename
** is written into zBuf[].  The calling function must insure that
** zBuf[] is big enough to hold the prefix plus 20 or so extra
** characters.
**
** Very random names are chosen so that the chance of a
** collision with an existing filename is very very small.
*/
static void randomName(struct rc4 *pRc4, char *zBuf, char *zPrefix){
  int i, j;
  static const char zRandomChars[] = "abcdefghijklmnopqrstuvwxyz0123456789";

** This file defines the interface to the database backend (Dbbe).
**
** The database backend is designed to be as general as possible
** so that it can easily be replaced by a different backend.
** This library was originally designed to support the following
** backends: GDBM, NDBM, SDBM, Berkeley DB.
**
** $Id: dbbe.h,v 1.5 2000/06/17 13:12:39 drh Exp $
*/
#ifndef _SQLITE_DBBE_H_
#define _SQLITE_DBBE_H_
#include <stdio.h>

/*
** The database backend supports two opaque structures.  A Dbbe is
** a context for the entire set of tables forming a complete
** database.  A DbbeTable is a single table.
**
** Note that at this level, the term "table" can mean either an
** SQL table or an SQL index.  In this module, a table stores a
** single arbitrary-length key and corresponding arbitrary-length
** data.  The differences between tables and indices, and the
** segregation of data into various fields or columns is handled
** by software at higher layers.
**
** The DbbeTable structure holds some state information, such as
** the key and data from the last retrieval.  For this reason, 
** the backend must allow the creation of multiple independent
** DbbeTable structures for each table in the database.
*/
typedef struct Dbbe Dbbe;

/* Retrieve the key or data used for the last fetch.  Only size
** bytes are read beginning with the offset-th byte.  The return
** value is the actual number of bytes read.
*/
int sqliteDbbeCopyKey(DbbeTable*, int offset, int size, char *zBuf);
int sqliteDbbeCopyData(DbbeTable*, int offset, int size, char *zBuf);

/* Retrieve the key or data.  The result is ephemeral.  In other words,
** the result is stored in a buffer that might be overwritten on the next
** call to any DBBE routine.  If the results are needed for longer than
** that, you must make a copy.
*/
char *sqliteDbbeReadKey(DbbeTable*, int offset);
char *sqliteDbbeReadData(DbbeTable*, int offset);

/* Return the length of the most recently fetched key or data. */
int sqliteDbbeKeyLength(DbbeTable*);
int sqliteDbbeDataLength(DbbeTable*);

**   drh@hwaci.com
**   http://www.hwaci.com/drh/
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle DELETE FROM statements.
**
** $Id: delete.c,v 1.5 2000/06/17 13:12:39 drh Exp $
*/
#include "sqliteInt.h"

/*
** Process a DELETE FROM statement.
*/
void sqliteDeleteFrom(
  Parse *pParse,         /* The parser context */
  Token *pTableName,     /* The table from which we should delete things */
  Expr *pWhere           /* The WHERE clause.  May be null */
){
  Vdbe *v;               /* The virtual database engine */
  Table *pTab;           /* The table from which records will be deleted */
  IdList *pTabList;      /* An ID list holding pTab and nothing else */
  int end, addr;         /* A couple addresses of generated code */
  int i;                 /* Loop counter */
  WhereInfo *pWInfo;     /* Information about the WHERE clause */
  Index *pIdx;           /* For looping over indices of the table */
  int base;              /* Index of the first available table cursor */

  /* Locate the table which we want to delete.  This table has to be
  ** put in an IdList structure because some of the subroutines we
  ** will be calling are designed to work with multiple tables and expect
  ** an IdList* parameter instead of just a Table* parameger.
  */
  pTabList = sqliteIdListAppend(0, pTableName);
  for(i=0; i<pTabList->nId; i++){
    pTabList->a[i].pTab = sqliteFindTable(pParse->db, pTabList->a[i].zName);
    if( pTabList->a[i].pTab==0 ){

  /* Begin the database scan
  */
  sqliteVdbeAddOp(v, OP_ListOpen, 0, 0, 0, 0);
  pWInfo = sqliteWhereBegin(pParse, pTabList, pWhere, 1);
  if( pWInfo==0 ) goto delete_from_cleanup;

  /* Remember the key of every item to be deleted.
  */
  sqliteVdbeAddOp(v, OP_ListWrite, 0, 0, 0, 0);

  /* End the database scan loop.
  */
  sqliteWhereEnd(pWInfo);

  /* Delete every item whose key was written to the list during the
  ** database scan.  We have to delete items after the scan is complete
  ** because deleting an item can change the scan order.
  */
  base = pParse->nTab;
  sqliteVdbeAddOp(v, OP_ListRewind, 0, 0, 0, 0);
  sqliteVdbeAddOp(v, OP_Open, base, 1, pTab->zName, 0);
  for(i=1, pIdx=pTab->pIndex; pIdx; i++, pIdx=pIdx->pNext){
    sqliteVdbeAddOp(v, OP_Open, base+i, 1, pIdx->zName, 0);
  }

** Boston, MA  02111-1307, USA.
**
** Author contact information:
**   drh@hwaci.com
**   http://www.hwaci.com/drh/
**
*************************************************************************
** This file contains routines used for analyzing expressions and
** for generating VDBE code that evaluates expressions.
**
** $Id: expr.c,v 1.17 2000/06/17 13:12:40 drh Exp $
*/
#include "sqliteInt.h"

/*
** Walk an expression tree.  Return 1 if the expression is constant
** and 0 if it involves variables.
*/

/*
** Walk the expression tree and process operators of the form:
**
**       expr IN (SELECT ...)
**
** These operators have to be processed before field names are
** resolved because each such operator increments pParse->nTab
** to reserve cursor numbers for its own use.  But pParse->nTab
** needs to be constant once we begin resolving field names.
**
** Actually, the processing of IN-SELECT is only started by this
** routine.  This routine allocates a cursor number to the IN-SELECT
** and then moves on.  The code generation is done by 
** sqliteExprResolveIds() which must be called afterwards.
*/

    }
  }
  return nErr;
}

/*
** Generate code into the current Vdbe to evaluate the given
** expression and leave the result on the top of stack.
*/
void sqliteExprCode(Parse *pParse, Expr *pExpr){
  Vdbe *v = pParse->pVdbe;
  int op;
  switch( pExpr->op ){
    case TK_PLUS:     op = OP_Add;      break;
    case TK_MINUS:    op = OP_Subtract; break;

        Token *p = &pExpr->pLeft->token;
        char *z = sqliteMalloc( p->n + 2 );
        sprintf(z, "-%.*s", p->n, p->z);
        sqliteVdbeAddOp(v, OP_String, 0, 0, z, 0);
        sqliteFree(z);
        break;
      }
      /* Fall through into TK_NOT */
    }
    case TK_NOT: {
      sqliteExprCode(pParse, pExpr->pLeft);
      sqliteVdbeAddOp(v, op, 0, 0, 0, 0);
      break;
    }
    case TK_ISNULL:

**   drh@hwaci.com
**   http://www.hwaci.com/drh/
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle INSERT statements.
**
** $Id: insert.c,v 1.10 2000/06/17 13:12:40 drh Exp $
*/
#include "sqliteInt.h"

/*
** This routine is call to handle SQL of the following forms:
**
**    insert into TABLE (IDLIST) values(EXPRLIST)
**    insert into TABLE (IDLIST) select
**
** The IDLIST following the table name is always optional.  If omitted,
** then a list of all columns for the table is substituted.  The IDLIST
** appears in the pField parameter.  pField is NULL if IDLIST is omitted.
**
** The pList parameter holds EXPRLIST in the first form of the INSERT
** statement above, and pSelect is NULL.  For the second form, pList is
** NULL and pSelect is a pointer to the select statement used to generate
** data for the insert.
*/
void sqliteInsert(
  Parse *pParse,        /* Parser context */
  Token *pTableName,    /* Name of table into which we are inserting */
  ExprList *pList,      /* List of values to be inserted */
  Select *pSelect,      /* A SELECT statement to use as the data source */
  IdList *pField        /* Field names corresponding to IDLIST. */
){
  Table *pTab;          /* The table to insert into */
  char *zTab;           /* Name of the table into which we are inserting */
  int i, j, idx;        /* Loop counters */
  Vdbe *v;              /* Generate code into this virtual machine */
  Index *pIdx;          /* For looping over indices of the table */
  int srcTab;           /* Date comes from this temporary cursor if >=0 */
  int nField;           /* Number of columns in the data */
  int base;             /* First available cursor */
  int iCont, iBreak;    /* Beginning and end of the loop over srcTab */

  /* Locate the table into which we will be inserting new information.
  */
  zTab = sqliteTableNameFromToken(pTableName);
  pTab = sqliteFindTable(pParse->db, zTab);
  sqliteFree(zTab);
  if( pTab==0 ){
    sqliteSetNString(&pParse->zErrMsg, "no such table: ", 0, 
        pTableName->z, pTableName->n, 0);
    pParse->nErr++;
    goto insert_cleanup;
  }
  if( pTab->readOnly ){
    sqliteSetString(&pParse->zErrMsg, "table ", pTab->zName,
        " may not be modified", 0);
    pParse->nErr++;
    goto insert_cleanup;
  }

  /* Allocate a VDBE
  */
  v = sqliteGetVdbe(pParse);
  if( v==0 ) goto insert_cleanup;

  /* Figure out how many columns of data are supplied.  If the data
  ** is comming from a SELECT statement, then this step has to generate
  ** all the code to implement the SELECT statement and leave the data
  ** in a temporary table.  If data is coming from an expression list,
  ** then we just have to count the number of expressions.
  */
  if( pSelect ){
    int rc;
    srcTab = pParse->nTab++;
    sqliteVdbeAddOp(v, OP_Open, srcTab, 1, 0, 0);
    rc = sqliteSelect(pParse, pSelect, SRT_Table, srcTab);
    if( rc ) goto insert_cleanup;
    assert( pSelect->pEList );
    nField = pSelect->pEList->nExpr;
  }else{
    srcTab = -1;
    assert( pList );
    nField = pList->nExpr;
  }

  /* Make sure the number of columns in the source data matches the number
  ** of columns to be inserted into the table.
  */
  if( pField==0 && nField!=pTab->nCol ){
    char zNum1[30];
    char zNum2[30];
    sprintf(zNum1,"%d", nField);
    sprintf(zNum2,"%d", pTab->nCol);
    sqliteSetString(&pParse->zErrMsg, "table ", pTab->zName,
       " has ", zNum2, " columns but ",

    sprintf(zNum1,"%d", nField);
    sprintf(zNum2,"%d", pField->nId);
    sqliteSetString(&pParse->zErrMsg, zNum1, " values for ",
       zNum2, " columns", 0);
    pParse->nErr++;
    goto insert_cleanup;
  }

  /* If the INSERT statement included an IDLIST term, then make sure
  ** all elements of the IDLIST really are columns of the table and 
  ** remember the column indices.
  */
  if( pField ){
    for(i=0; i<pField->nId; i++){
      pField->a[i].idx = -1;
    }
    for(i=0; i<pField->nId; i++){
      for(j=0; j<pTab->nCol; j++){
        if( sqliteStrICmp(pField->a[i].zName, pTab->aCol[j].zName)==0 ){
          pField->a[i].idx = j;
          break;
        }
      }
      if( j>=pTab->nCol ){
        sqliteSetString(&pParse->zErrMsg, "table ", pTab->zName,
           " has no column named ", pField->a[i].zName, 0);
        pParse->nErr++;
        goto insert_cleanup;
      }
    }
  }

  /* Open cursors into the table that is received the new data and
  ** all indices of that table.
  */
  base = pParse->nTab;
  sqliteVdbeAddOp(v, OP_Open, base, 1, pTab->zName, 0);
  for(idx=1, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, idx++){
    sqliteVdbeAddOp(v, OP_Open, idx+base, 1, pIdx->zName, 0);
  }

  /* If the data source is a SELECT statement, then we have to create
  ** a loop because there might be multiple rows of data.  If the data
  ** source is an expression list, then exactly one row will be inserted
  ** and the loop is not used.
  */
  if( srcTab>=0 ){
    sqliteVdbeAddOp(v, OP_Rewind, srcTab, 0, 0, 0);
    iBreak = sqliteVdbeMakeLabel(v);
    iCont = sqliteVdbeAddOp(v, OP_Next, srcTab, iBreak, 0, 0);
  }

  /* Create a new entry in the table and fill it with data.
  */
  sqliteVdbeAddOp(v, OP_New, 0, 0, 0, 0);
  if( pTab->pIndex ){
    sqliteVdbeAddOp(v, OP_Dup, 0, 0, 0, 0);
  }
  for(i=0; i<pTab->nCol; i++){
    if( pField==0 ){
      j = i;

      sqliteVdbeAddOp(v, OP_Field, srcTab, i, 0, 0); 
    }else{
      sqliteExprCode(pParse, pList->a[j].pExpr);
    }
  }
  sqliteVdbeAddOp(v, OP_MakeRecord, pTab->nCol, 0, 0, 0);
  sqliteVdbeAddOp(v, OP_Put, base, 0, 0, 0);

  /* Create appropriate entries for the new data row in all indices
  ** of the table.
  */
  for(idx=1, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, idx++){
    if( pIdx->pNext ){
      sqliteVdbeAddOp(v, OP_Dup, 0, 0, 0, 0);
    }
    for(i=0; i<pIdx->nField; i++){
      int idx = pIdx->aiField[i];
      if( pField==0 ){

        sqliteVdbeAddOp(v, OP_Field, srcTab, idx, 0, 0); 
      }else{
        sqliteExprCode(pParse, pList->a[j].pExpr);
      }
    }
    sqliteVdbeAddOp(v, OP_MakeKey, pIdx->nField, 0, 0, 0);
    sqliteVdbeAddOp(v, OP_PutIdx, idx+base, 0, 0, 0);

  }

  /* The bottom of the loop, if the data source is a SELECT statement
  */
  if( srcTab>=0 ){
    sqliteVdbeAddOp(v, OP_Goto, 0, iCont, 0, 0);
    sqliteVdbeAddOp(v, OP_Noop, 0, 0, 0, iBreak);
  }

insert_cleanup:
  if( pList ) sqliteExprListDelete(pList);
  if( pSelect ) sqliteSelectDelete(pSelect);
  sqliteIdListDelete(pField);
}

**   drh@hwaci.com
**   http://www.hwaci.com/drh/
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle UPDATE statements.
**
** $Id: update.c,v 1.6 2000/06/17 13:12:40 drh Exp $
*/
#include "sqliteInt.h"

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

  int base;              /* Index of first available table cursor */
  Index **apIdx = 0;     /* An array of indices that need updating too */
  int *aXRef = 0;        /* aXRef[i] is the index in pChanges->a[] of the
                         ** an expression for the i-th field of the table.
                         ** aXRef[i]==-1 if the i-th field is not changed. */

  /* Locate the table which we want to update.  This table has to be
  ** put in an IdList structure because some of the subroutines we
  ** will be calling are designed to work with multiple tables and expect
  ** an IdList* parameter instead of just a Table* parameger.
  */
  pTabList = sqliteIdListAppend(0, pTableName);
  for(i=0; i<pTabList->nId; i++){
    pTabList->a[i].pTab = sqliteFindTable(pParse->db, pTabList->a[i].zName);
    if( pTabList->a[i].pTab==0 ){

      goto update_cleanup;
    }
    if( sqliteExprCheck(pParse, pChanges->a[i].pExpr, 0, 0) ){
      goto update_cleanup;
    }
    for(j=0; j<pTab->nCol; j++){
      if( strcmp(pTab->aCol[j].zName, pChanges->a[i].zName)==0 ){

        aXRef[j] = i;
        break;
      }
    }
    if( j>=pTab->nCol ){
      sqliteSetString(&pParse->zErrMsg, "no such field: ", 
         pChanges->a[i].zName, 0);

  sqliteVdbeAddOp(v, OP_Open, base, 1, pTab->zName, 0);
  for(i=0; i<nIdx; i++){
    sqliteVdbeAddOp(v, OP_Open, base+i+1, 1, apIdx[i]->zName, 0);
  }

  /* Loop over every record that needs updating.  We have to load
  ** the old data for each record to be updated because some fields
  ** might not change and we will need to copy the old value.
  ** Also, the old data is needed to delete the old index entires.
  */
  end = sqliteVdbeMakeLabel(v);
  addr = sqliteVdbeAddOp(v, OP_ListRead, 0, end, 0, 0);
  sqliteVdbeAddOp(v, OP_Dup, 0, 0, 0, 0);
  sqliteVdbeAddOp(v, OP_Fetch, base, 0, 0, 0);

#   drh@hwaci.com
#   http://www.hwaci.com/drh/
#
#***********************************************************************
# This file implements regression tests for SQLite library.  The
# focus of this file is testing the CREATE INDEX statement.
#
# $Id: index.test,v 1.5 2000/06/17 13:12:40 drh Exp $

set testdir [file dirname $argv0]
source $testdir/tester.tcl

# Create a basic index and verify it is added to sqlite_master
#
do_test index-1.1 {

# Try adding an index to a table that does not exist
#
do_test index-2.1 {
  set v [catch {execsql {CREATE INDEX index1 ON test1(f1)}} msg]
  lappend v $msg
} {1 {no such table: test1}}

# Try adding an index on a column of a table where the table
# exists but the column does not.
#
do_test index-2.1 {
  execsql {CREATE TABLE test1(f1 int, f2 int, f3 int)}
  set v [catch {execsql {CREATE INDEX index1 ON test1(f4)}} msg]
  lappend v $msg
} {1 {table test1 has no column named f4}}

# Try an index with some columns that match and others that do now.
#
do_test index-2.2 {
  set v [catch {execsql {CREATE INDEX index1 ON test1(f1, f2, f4, f3)}} msg]
  execsql {DROP TABLE test1}
  lappend v $msg
} {1 {table test1 has no column named f4}}

# Try creating a bunch of indices on the same table
#
set r {}
for {set i 1} {$i<100} {incr i} {
  lappend r index$i
}