SQLite

  int newmask;           /* Mask of NEW.* columns accessed by BEFORE triggers */
  int iEph = 0;          /* Ephemeral table holding all primary key values */
  int nKey = 0;          /* Number of elements in regKey for WITHOUT ROWID */
  int aiCurOnePass[2];   /* The write cursors opened by WHERE_ONEPASS */
  int addrOpen;          /* Address of OP_OpenEphemeral */
  int iPk;               /* First of nPk cells holding PRIMARY KEY value */
  i16 nPk;               /* Number of components of the PRIMARY KEY */
  int bReplace = 0;      /* True if REPLACE conflict resolution might happen */

  /* Register Allocations */
  int regRowCount = 0;   /* A count of rows changed */
  int regOldRowid = 0;   /* The old rowid */
  int regNewRowid = 0;   /* The new rowid */
  int regNew = 0;        /* Content of the NEW.* table in triggers */
  int regOld = 0;        /* Content of OLD.* table in triggers */

    }else{
      reg = 0;
      for(i=0; i<pIdx->nKeyCol; i++){
        i16 iIdxCol = pIdx->aiColumn[i];
        if( iIdxCol<0 || aXRef[iIdxCol]>=0 ){
          reg = ++pParse->nMem;
          pParse->nMem += pIdx->nColumn;
          if( (onError==OE_Replace)
           || (onError==OE_Default && pIdx->onError==OE_Replace) 
          ){
            bReplace = 1;
          }
          break;
        }
      }
    }
    if( reg==0 ) aToOpen[j+1] = 0;
    aRegIdx[j] = reg;
  }
  if( bReplace ){
    /* If REPLACE conflict resolution might be invoked, open cursors on all 
    ** indexes in case they are needed to delete records.  */
    memset(aToOpen, 1, nIdx+1);
  }

  /* Begin generating code. */
  v = sqlite3GetVdbe(pParse);
  if( v==0 ) goto update_cleanup;
  if( pParse->nested==0 ) sqlite3VdbeCountChanges(v);
  sqlite3BeginWriteOperation(pParse, 1, iDb);

    iEph = pParse->nTab++;

    sqlite3VdbeAddOp2(v, OP_Null, 0, iPk);
    addrOpen = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, iEph, nPk);
    sqlite3VdbeSetP4KeyInfo(pParse, pPk);
  }

  /* Begin the database scan. 
  **
  ** Do not consider a single-pass strategy for a multi-row update if
  ** there are any triggers or foreign keys to process, or rows may
  ** be deleted as a result of REPLACE conflict handling. Any of these
  ** things might disturb a cursor being used to scan through the table
  ** or index, causing a single-pass approach to malfunction.  */
  flags = WHERE_ONEPASS_DESIRED | WHERE_SEEK_TABLE;
  if( !pParse->nested && !pTrigger && !hasFK && !chngKey && !bReplace ){
    flags |= WHERE_ONEPASS_MULTIROW;
  }
  pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 0, 0, flags, iIdxCur);
  if( pWInfo==0 ) goto update_cleanup;

  /* A one-pass strategy that might update more than one row may not
  ** be used if any column of the index used for the scan is being

  if( eOnePass!=ONEPASS_MULTI ){
    sqlite3WhereEnd(pWInfo);
  }

  labelBreak = sqlite3VdbeMakeLabel(v);
  if( !isView ){
    int addrOnce = 0;

    /* Open every index that needs updating. */














    if( eOnePass!=ONEPASS_OFF ){
      if( aiCurOnePass[0]>=0 ) aToOpen[aiCurOnePass[0]-iBaseCur] = 0;
      if( aiCurOnePass[1]>=0 ) aToOpen[aiCurOnePass[1]-iBaseCur] = 0;
    }

    if( eOnePass==ONEPASS_MULTI && (nIdx-(aiCurOnePass[1]>=0))>0 ){
      addrOnce = sqlite3VdbeAddOp0(v, OP_Once); VdbeCoverage(v);
    }
    sqlite3OpenTableAndIndices(pParse, pTab, OP_OpenWrite, 0, iBaseCur, aToOpen,
                               0, 0);
    if( addrOnce ) sqlite3VdbeJumpHere(v, addrOnce);
  }

  /* Top of the update loop */
  if( eOnePass!=ONEPASS_OFF ){
    if( !isView && aiCurOnePass[0]!=iDataCur && aiCurOnePass[1]!=iDataCur ){
      assert( pPk );
      sqlite3VdbeAddOp4Int(v, OP_NotFound, iDataCur, labelBreak, regKey, nKey);

        sqlite3ExprCodeGetColumnOfTable(v, pTab, iDataCur, i, regNew+i);
      }
    }
  }

  if( !isView ){
    int addr1 = 0;        /* Address of jump instruction */


    /* Do constraint checks. */
    assert( regOldRowid>0 );
    sqlite3GenerateConstraintChecks(pParse, pTab, aRegIdx, iDataCur, iIdxCur,
        regNewRowid, regOldRowid, chngKey, onError, labelContinue, &bReplace,
        aXRef);

  UPDATE t4 SET c=c+2 WHERE c>2;
  SELECT a, c FROM t4 ORDER BY a;
} {1 5 2 6}

#-------------------------------------------------------------------------
#
foreach {tn sql} {
  1 { 
    CREATE TABLE b1(a INTEGER PRIMARY KEY, b, c);
    CREATE TABLE c1(a INTEGER PRIMARY KEY, b, c, d)
  }
  2 { 
    CREATE TABLE b1(a INT PRIMARY KEY, b, c) WITHOUT ROWID;
    CREATE TABLE c1(a INT PRIMARY KEY, b, c, d) WITHOUT ROWID;
  }
} {
  execsql { DROP TABLE IF EXISTS b1; DROP TABLE IF EXISTS c1; }
  execsql $sql

  do_execsql_test 4.$tn.0 {
    CREATE UNIQUE INDEX b1c ON b1(c);

    INSERT INTO b1 VALUES(1, 'a', 1);
    INSERT INTO b1 VALUES(2, 'b', 15);
    INSERT INTO b1 VALUES(3, 'c', 3);
    INSERT INTO b1 VALUES(4, 'd', 4);
    INSERT INTO b1 VALUES(5, 'e', 5);
    INSERT INTO b1 VALUES(6, 'f', 6);
    INSERT INTO b1 VALUES(7, 'g', 7);
  }

  do_execsql_test 4.$tn.1 {
    UPDATE OR REPLACE b1 SET c=c+10 WHERE a BETWEEN 4 AND 7;
    SELECT * FROM b1 ORDER BY a;
  } {
    1 a 1
    3 c 3
    4 d 14
    5 e 15
    6 f 16
    7 g 17
  }

  do_execsql_test 4.$tn.2 {
    CREATE INDEX c1d ON c1(d, b);
    CREATE UNIQUE INDEX c1c ON c1(c, b);

    INSERT INTO c1 VALUES(1, 'a', 1,  1);
    INSERT INTO c1 VALUES(2, 'a', 15, 2);
    INSERT INTO c1 VALUES(3, 'a', 3,  3);
    INSERT INTO c1 VALUES(4, 'a', 4,  4);
    INSERT INTO c1 VALUES(5, 'a', 5,  5);
    INSERT INTO c1 VALUES(6, 'a', 6,  6);
    INSERT INTO c1 VALUES(7, 'a', 7,  7);
  }

  do_execsql_test 4.$tn.3 {
    UPDATE OR REPLACE c1 SET c=c+10 WHERE d BETWEEN 4 AND 7;
    SELECT * FROM c1 ORDER BY a;
  } {
    1 a 1 1
    3 a 3 3
    4 a 14 4
    5 a 15 5
    6 a 16 6
    7 a 17 7
  }

  do_execsql_test 4.$tn.4 { PRAGMA integrity_check } ok

  do_execsql_test 4.$tn.5 {
    DROP INDEX c1d;
    DROP INDEX c1c;
    DELETE FROM c1;

    INSERT INTO c1 VALUES(1, 'a', 1,  1);
    INSERT INTO c1 VALUES(2, 'a', 15, 2);
    INSERT INTO c1 VALUES(3, 'a', 3,  3);
    INSERT INTO c1 VALUES(4, 'a', 4,  4);
    INSERT INTO c1 VALUES(5, 'a', 5,  5);
    INSERT INTO c1 VALUES(6, 'a', 6,  6);
    INSERT INTO c1 VALUES(7, 'a', 7,  7);

    CREATE INDEX c1d ON c1(d);
    CREATE UNIQUE INDEX c1c ON c1(c);
  }

  do_execsql_test 4.$tn.6 {
    UPDATE OR REPLACE c1 SET c=c+10 WHERE d BETWEEN 4 AND 7;
    SELECT * FROM c1 ORDER BY a;
  } {
    1 a 1 1
    3 a 3 3
    4 a 14 4
    5 a 15 5
    6 a 16 6
    7 a 17 7
  }
}

finish_test