SQLite

  ** use for the old.* references in the triggers.  */
  if( sqlite3FkRequired(pParse, pTab, 0, 0) || pTrigger ){
    u32 mask;                     /* Mask of OLD.* columns in use */
    int iCol;                     /* Iterator used while populating OLD.* */

    /* TODO: Could use temporary registers here. Also could attempt to
    ** avoid copying the contents of the rowid register.  */
    mask = sqlite3TriggerColmask(
        pParse, pTrigger, 0, 0, TRIGGER_BEFORE|TRIGGER_AFTER, pTab, onconf
    );
    mask |= sqlite3FkOldmask(pParse, pTab);
    iOld = pParse->nMem+1;
    pParse->nMem += (1 + pTab->nCol);

    /* Populate the OLD.* pseudo-table register array. These values will be 
    ** used by any BEFORE and AFTER triggers that exist.  */
    sqlite3VdbeAddOp2(v, OP_Copy, iRowid, iOld);

          cnt++;
          if( iCol<0 ){
            pExpr->affinity = SQLITE_AFF_INTEGER;
          }else if( pExpr->iTable==0 ){
            testcase( iCol==31 );
            testcase( iCol==32 );
            pParse->oldmask |= (iCol>=32 ? 0xffffffff : (((u32)1)<<iCol));
          }else{
            testcase( iCol==31 );
            testcase( iCol==32 );
            pParse->newmask |= (iCol>=32 ? 0xffffffff : (((u32)1)<<iCol));
          }
          pExpr->iColumn = (i16)iCol;
          pExpr->pTab = pTab;
          isTrigger = 1;
        }
      }
    }

**
** A Vdbe sub-program that implements the body and WHEN clause of trigger
** TriggerPrg.pTrigger, assuming a default ON CONFLICT clause of
** TriggerPrg.orconf, is stored in the TriggerPrg.pProgram variable.
** The Parse.pTriggerPrg list never contains two entries with the same
** values for both pTrigger and orconf.
**
** The TriggerPrg.aColmask[0] variable is set to a mask of old.* columns
** accessed (or set to 0 for triggers fired as a result of INSERT 
** statements). Similarly, the TriggerPrg.aColmask[1] variable is set to
** a mask of new.* columns used by the program.
*/
struct TriggerPrg {
  Trigger *pTrigger;      /* Trigger this program was coded from */
  int orconf;             /* Default ON CONFLICT policy */
  SubProgram *pProgram;   /* Program implementing pTrigger/orconf */
  u32 aColmask[2];        /* Masks of old.*, new.* columns accessed */
  TriggerPrg *pNext;      /* Next entry in Parse.pTriggerPrg list */
};

/*
** An SQL parser context.  A copy of this structure is passed through
** the parser and down into all the parser action routine in order to
** carry around information that is global to the entire parse.

  AutoincInfo *pAinc;  /* Information about AUTOINCREMENT counters */
  int nMaxArg;         /* Max args passed to user function by sub-program */

  /* Information used while coding trigger programs. */
  Parse *pToplevel;    /* Parse structure for main program (or NULL) */
  Table *pTriggerTab;  /* Table triggers are being coded for */
  u32 oldmask;         /* Mask of old.* columns referenced */
  u32 newmask;         /* Mask of new.* columns referenced */
  u8 eTriggerOp;       /* TK_UPDATE, TK_INSERT or TK_DELETE */
  u8 eOrconf;          /* Default ON CONFLICT policy for trigger steps */
  u8 disableTriggers;  /* True to disable triggers */

  /* Above is constant between recursions.  Below is reset before and after
  ** each recursion */

  TriggerStep *sqlite3TriggerSelectStep(sqlite3*,Select*);
  TriggerStep *sqlite3TriggerInsertStep(sqlite3*,Token*, IdList*,
                                        ExprList*,Select*,u8);
  TriggerStep *sqlite3TriggerUpdateStep(sqlite3*,Token*,ExprList*, Expr*, u8);
  TriggerStep *sqlite3TriggerDeleteStep(sqlite3*,Token*, Expr*);
  void sqlite3DeleteTrigger(sqlite3*, Trigger*);
  void sqlite3UnlinkAndDeleteTrigger(sqlite3*,int,const char*);
  u32 sqlite3TriggerColmask(Parse*,Trigger*,ExprList*,int,int,Table*,int);
# define sqlite3ParseToplevel(p) ((p)->pToplevel ? (p)->pToplevel : (p))
#else
# define sqlite3TriggersExist(B,C,D,E,F) 0
# define sqlite3DeleteTrigger(A,B)
# define sqlite3DropTriggerPtr(A,B)
# define sqlite3UnlinkAndDeleteTrigger(A,B,C)
# define sqlite3CodeRowTrigger(A,B,C,D,E,F,G,H,I)
# define sqlite3CodeRowTriggerDirect(A,B,C,D,E,F)
# define sqlite3TriggerList(X, Y) 0
# define sqlite3ParseToplevel(p) p
# define sqlite3TriggerColmask(A,B,C,D,E,F,G) 0
#endif

int sqlite3JoinType(Parse*, Token*, Token*, Token*);
void sqlite3CreateForeignKey(Parse*, ExprList*, Token*, ExprList*, int);
void sqlite3DeferForeignKey(Parse*, int);
#ifndef SQLITE_OMIT_AUTHORIZATION
  void sqlite3AuthRead(Parse*,Expr*,Schema*,SrcList*);

  pPrg->pNext = pTop->pTriggerPrg;
  pTop->pTriggerPrg = pPrg;
  pPrg->pProgram = pProgram = sqlite3DbMallocZero(db, sizeof(SubProgram));
  if( !pProgram ) return 0;
  pProgram->nRef = 1;
  pPrg->pTrigger = pTrigger;
  pPrg->orconf = orconf;
  pPrg->aColmask[0] = 0xffffffff;
  pPrg->aColmask[1] = 0xffffffff;

  /* Allocate and populate a new Parse context to use for coding the 
  ** trigger sub-program.  */
  pSubParse = sqlite3StackAllocZero(db, sizeof(Parse));
  if( !pSubParse ) return 0;
  memset(&sNC, 0, sizeof(sNC));
  sNC.pParse = pSubParse;

    transferParseError(pParse, pSubParse);
    if( db->mallocFailed==0 ){
      pProgram->aOp = sqlite3VdbeTakeOpArray(v, &pProgram->nOp, &pTop->nMaxArg);
    }
    pProgram->nMem = pSubParse->nMem;
    pProgram->nCsr = pSubParse->nTab;
    pProgram->token = (void *)pTrigger;
    pPrg->aColmask[0] = pSubParse->oldmask;
    pPrg->aColmask[1] = pSubParse->newmask;
    sqlite3VdbeDelete(v);
  }

  assert( !pSubParse->pAinc       && !pSubParse->pZombieTab );
  assert( !pSubParse->pTriggerPrg && !pSubParse->nMaxArg );
  sqlite3StackFree(db, pSubParse);

    ){
      sqlite3CodeRowTriggerDirect(pParse, p, pTab, reg, orconf, ignoreJump);
    }
  }
}

/*
** Triggers may access values stored in the old.* or new.* pseudo-table. 
** This function returns a 32-bit bitmask indicating which columns of the 
** old.* or new.* tables actually are used by triggers. This information 
** may be used by the caller, for example, to avoid having to load the entire
** old.* record into memory when executing an UPDATE or DELETE command.

**
** Bit 0 of the returned mask is set if the left-most column of the
** table may be accessed using an [old|new].<col> reference. Bit 1 is set if
** the second leftmost column value is required, and so on. If there
** are more than 32 columns in the table, and at least one of the columns
** with an index greater than 32 may be accessed, 0xffffffff is returned.
**
** It is not possible to determine if the old.rowid or new.rowid column is 
** accessed by triggers. The caller must always assume that it is.
**
** Parameter isNew must be either 1 or 0. If it is 0, then the mask returned
** applies to the old.* table. If 1, the new.* table.
**
** Parameter tr_tm must be a mask with one or both of the TRIGGER_BEFORE
** and TRIGGER_AFTER bits set. Values accessed by BEFORE triggers are only
** included in the returned mask if the TRIGGER_BEFORE bit is set in the
** tr_tm parameter. Similarly, values accessed by AFTER triggers are only
** included in the returned mask if the TRIGGER_AFTER bit is set in tr_tm.
*/
u32 sqlite3TriggerColmask(
  Parse *pParse,       /* Parse context */
  Trigger *pTrigger,   /* List of triggers on table pTab */
  ExprList *pChanges,  /* Changes list for any UPDATE OF triggers */
  int isNew,           /* 1 for new.* ref mask, 0 for old.* ref mask */
  int tr_tm,           /* Mask of TRIGGER_BEFORE|TRIGGER_AFTER */
  Table *pTab,         /* The table to code triggers from */
  int orconf           /* Default ON CONFLICT policy for trigger steps */
){
  const int op = pChanges ? TK_UPDATE : TK_DELETE;
  u32 mask = 0;
  Trigger *p;

  assert( isNew==1 || isNew==0 );
  for(p=pTrigger; p; p=p->pNext){
    if( p->op==op && (tr_tm&p->tr_tm)
     && checkColumnOverlap(p->pColumns,pChanges)
    ){
      TriggerPrg *pPrg;
      pPrg = getRowTrigger(pParse, p, pTab, orconf);
      if( pPrg ){
        mask |= pPrg->aColmask[isNew];
      }
    }
  }

  return mask;
}

#endif /* !defined(SQLITE_OMIT_TRIGGER) */

                         ** aXRef[i]==-1 if the i-th column is not changed. */
  int chngRowid;         /* True if the record number is being changed */
  Expr *pRowidExpr = 0;  /* Expression defining the new record number */
  int openAll = 0;       /* True if all indices need to be opened */
  AuthContext sContext;  /* The authorization context */
  NameContext sNC;       /* The name-context to resolve expressions in */
  int iDb;               /* Database containing the table being updated */

  int okOnePass;         /* True for one-pass algorithm without the FIFO */
  int hasFK;             /* True if foreign key processing is required */

#ifndef SQLITE_OMIT_TRIGGER
  int isView;            /* True when updating a view (INSTEAD OF trigger) */
  Trigger *pTrigger;     /* List of triggers on pTab, if required */
  int tmask;             /* Mask of TRIGGER_BEFORE|TRIGGER_AFTER */
#endif
  int newmask;

  /* Register Allocations */
  int regRowCount = 0;   /* A count of rows changed */
  int regOldRowid;       /* The old rowid */
  int regNewRowid;       /* The new rowid */
  int regNew;
  int regOld = 0;

  if( pTab==0 ) goto update_cleanup;
  iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);

  /* Figure out if we have any triggers and if the table being
  ** updated is a view.
  */
#ifndef SQLITE_OMIT_TRIGGER
  pTrigger = sqlite3TriggersExist(pParse, pTab, TK_UPDATE, pChanges, &tmask);
  isView = pTab->pSelect!=0;
  assert( pTrigger || tmask==0 );
#else
# define pTrigger 0
# define isView 0
# define tmask 0
#endif
#ifdef SQLITE_OMIT_VIEW
# undef isView
# define isView 0
#endif

  if( sqlite3ViewGetColumnNames(pParse, pTab) ){
    goto update_cleanup;
  }
  if( sqlite3IsReadOnly(pParse, pTab, tmask) ){
    goto update_cleanup;
  }
  aXRef = sqlite3DbMallocRaw(db, sizeof(int) * pTab->nCol );
  if( aXRef==0 ) goto update_cleanup;
  for(i=0; i<pTab->nCol; i++) aXRef[i] = -1;

  /* Allocate a cursors for the main database table and for all indices.

    sqlite3VdbeAddOp1(v, OP_MustBeInt, regNewRowid);
  }

  /* If there are triggers on this table, populate an array of registers 
  ** with the required old.* column data.  */
  if( hasFK || pTrigger ){
    u32 oldmask = (hasFK ? sqlite3FkOldmask(pParse, pTab) : 0);
    oldmask |= sqlite3TriggerColmask(pParse, 
        pTrigger, pChanges, 0, TRIGGER_BEFORE|TRIGGER_AFTER, pTab, onError
    );
    for(i=0; i<pTab->nCol; i++){
      if( aXRef[i]<0 || oldmask==0xffffffff || (oldmask & (1<<i)) ){
        sqlite3VdbeAddOp3(v, OP_Column, iCur, i, regOld+i);
        sqlite3ColumnDefault(v, pTab, i, regOld+i);
      }else{
        sqlite3VdbeAddOp2(v, OP_Null, 0, regOld+i);
      }
    }
    if( chngRowid==0 ){
      sqlite3VdbeAddOp2(v, OP_Copy, regOldRowid, regNewRowid);
    }
  }

  /* Populate the array of registers beginning at regNew with the new
  ** row data. This array is used to check constaints, create the new
  ** table and index records, and as the values for any new.* references
  ** made by triggers.
  **
  ** If there are one or more BEFORE triggers, then do not populate the
  ** registers associated with columns that are (a) not modified by
  ** this UPDATE statement and (b) not accessed by new.* references. The
  ** values for registers not modified by the UPDATE must be reloaded from 
  ** the database after the BEFORE triggers are fired anyway (as the trigger 
  ** may have modified them). So not loading those that are not going to
  ** be used eliminates some redundant opcodes.
  */
  newmask = sqlite3TriggerColmask(
      pParse, pTrigger, pChanges, 1, TRIGGER_BEFORE, pTab, onError
  );
  for(i=0; i<pTab->nCol; i++){
    if( i==pTab->iPKey ){
      sqlite3VdbeAddOp2(v, OP_Null, 0, regNew+i);
    }else{
      j = aXRef[i];
      if( j>=0 ){
        sqlite3ExprCode(pParse, pChanges->a[j].pExpr, regNew+i);
      }else if( 0==(tmask&TRIGGER_BEFORE) || i>31 || (newmask&(1<<i)) ){
        /* This branch loads the value of a column that will not be changed 
        ** into a register. This is done if there are no BEFORE triggers, or
        ** if there are one or more BEFORE triggers that use this value via
        ** a new.* reference in a trigger program.
        */
        sqlite3VdbeAddOp3(v, OP_Column, iCur, i, regNew+i);
        sqlite3ColumnDefault(v, pTab, i, regNew+i);


      }
    }
  }

  /* Fire any BEFORE UPDATE triggers. This happens before constraints are
  ** verified. One could argue that this is wrong.
  */
  if( tmask&TRIGGER_BEFORE ){
    sqlite3VdbeAddOp2(v, OP_Affinity, regNew, pTab->nCol);
    sqlite3TableAffinityStr(v, pTab);
    sqlite3CodeRowTrigger(pParse, pTrigger, TK_UPDATE, pChanges, 
        TRIGGER_BEFORE, pTab, regOldRowid, onError, addr);

    /* The row-trigger may have deleted the row being updated. In this
    ** case, jump to the next row. No updates or AFTER triggers are 
    ** required. This behaviour - what happens when the row being updated
    ** is deleted or renamed by a BEFORE trigger - is left undefined in the
    ** documentation.
    */
    sqlite3VdbeAddOp3(v, OP_NotExists, iCur, addr, regOldRowid);

    /* If it did not delete it, the row-trigger may still have modified 
    ** some of the columns of the row being updated. Load the values for 
    ** all columns not modified by the update statement into their 
    ** registers in case this has happened.
    */
    for(i=0; i<pTab->nCol; i++){
      if( aXRef[i]<0 && i!=pTab->iPKey ){
        sqlite3VdbeAddOp3(v, OP_Column, iCur, i, regNew+i);
        sqlite3ColumnDefault(v, pTab, i, regNew+i);
      }
    }
  }

  if( !isView ){
    int j1;                       /* Address of jump instruction */

    /* Do constraint checks. */
    sqlite3GenerateConstraintChecks(pParse, pTab, iCur, regNewRowid,
        aRegIdx, (chngRowid?regOldRowid:0), 1, onError, addr, 0);

    /* Do FK constraint checks. */
    if( hasFK ){

    CREATE TRIGGER t9r1 AFTER DELETE ON t9 BEGIN
      DELETE FROM t9 WHERE b=old.a;
    END;
    DELETE FROM t9 WHERE b=4;
    SELECT a FROM t9 ORDER BY a;
  }
} {1 2 3 4}

# At one point (between versions 3.6.18 and 3.6.20 inclusive), an UPDATE 
# that fired a BEFORE trigger that itself updated the same row as the 
# statement causing it to fire was causing a strange side-effect: The 
# values updated by the statement within the trigger were being overwritten 
# by the values in the new.* array, even if those values were not 
# themselves written by the parent UPDATE statement.
#
# Technically speaking this was not a bug. The SQLite documentation says
# that if a BEFORE UPDATE or BEFORE DELETE trigger modifies or deletes the
# row that the parent statement is operating on the results are undefined. 
# But as of 3.6.21 behaviour is restored to the way it was in versions
# 3.6.17 and earlier to avoid causing unnecessary difficulties.
#
do_test triggerC-10.1 {
  execsql {
    CREATE TABLE t10(a, updatecnt DEFAULT 0);
    CREATE TRIGGER t10_bu BEFORE UPDATE OF a ON t10 BEGIN
      UPDATE t10 SET updatecnt = updatecnt+1 WHERE rowid = old.rowid;
    END;
    INSERT INTO t10(a) VALUES('hello');
  }

  # Before the problem was fixed, table t10 would contain the tuple 
  # (world, 0) after running the following script (because the value
  # 1 written to column "updatecnt" was clobbered by the old value 0).
  #
  execsql {
    UPDATE t10 SET a = 'world';
    SELECT * FROM t10;
  }
} {world 1}

do_test triggerC-10.2 {
  execsql {
    UPDATE t10 SET a = 'tcl', updatecnt = 5;
    SELECT * FROM t10;
  }
} {tcl 5}

do_test triggerC-10.3 {
  execsql {
    CREATE TABLE t11(
      c1,   c2,  c3,  c4,  c5,  c6,  c7,  c8,  c9, c10,
      c11, c12, c13, c14, c15, c16, c17, c18, c19, c20,
      c21, c22, c23, c24, c25, c26, c27, c28, c29, c30,
      c31, c32, c33, c34, c35, c36, c37, c38, c39, c40
    );

    CREATE TRIGGER t11_bu BEFORE UPDATE OF c1 ON t11 BEGIN
      UPDATE t11 SET c31 = c31+1, c32=c32+1 WHERE rowid = old.rowid;
    END;

    INSERT INTO t11 VALUES(
      1,   2,  3,  4,  5,  6,  7,  8,  9, 10,
      11, 12, 13, 14, 15, 16, 17, 18, 19, 20,
      21, 22, 23, 24, 25, 26, 27, 28, 29, 30,
      31, 32, 33, 34, 35, 36, 37, 38, 39, 40
    );
  }

  # Before the problem was fixed, table t10 would contain the tuple 
  # (world, 0) after running the following script (because the value
  # 1 written to column "updatecnt" was clobbered by the old value 0).
  #
  execsql {
    UPDATE t11 SET c4=35, c33=22, c1=5;
    SELECT * FROM t11;
  } 
} {5 2 3 35 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 32 33 22 34 35 36 37 38 39 40}


finish_test