SQLite

  /* Fire any BEFORE UPDATE triggers. This happens before constraints are
  ** verified. One could argue that this is wrong.  */
  if( pTrigger ){
    sqlite3VdbeAddOp2(v, OP_Affinity, regNew, pTab->nCol);
    sqlite3TableAffinityStr(v, pTab);
    sqlite3CodeRowTrigger(pParse, pTrigger, TK_UPDATE, pChanges, 
        TRIGGER_BEFORE, pTab, -1, 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( !isView ){

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

  SubProgram *pProgram;   /* Sub-program to execute */
  void *t;                /* Token identifying trigger */

  pProgram = pOp->p4.pProgram;
  pRt = &p->aMem[pOp->p3];
  assert( pProgram->nOp>0 );
  
  /* If the SQLITE_RecTriggers flag is clear, then recursive invocation of
  ** triggers is disabled for backwards compatibility (flag set/cleared by
  ** the "PRAGMA recursive_triggers" command). 
  ** 
  ** It is recursive invocation of triggers, at the SQL level, that is 
  ** disabled. In some cases a single trigger may generate more than one 
  ** SubProgram (if the trigger may be executed with more than one different 
  ** ON CONFLICT algorithm). SubProgram structures associated with a
  ** single trigger all have the same value for the SubProgram.token 
  ** variable.

  }
} {1}

#-------------------------------------------------------------------------
# Test some of the "undefined behaviour" associated with triggers. The
# undefined behaviour occurs when a row being updated or deleted is 
# manipulated by a BEFORE trigger.
# 
do_test triggerC-7.1 {
  execsql {
    CREATE TABLE t8(x);
    CREATE TABLE t7(a, b);
    INSERT INTO t7 VALUES(1, 2);
    INSERT INTO t7 VALUES(3, 4);
    INSERT INTO t7 VALUES(5, 6);
    CREATE TRIGGER t7t BEFORE UPDATE ON t7 BEGIN
      DELETE FROM t7 WHERE a = 1;
    END;
    CREATE TRIGGER t7ta AFTER UPDATE ON t7 BEGIN
      INSERT INTO t8 VALUES('after fired ' || old.rowid || '->' || new.rowid);
    END;
  }
} {}
do_test triggerC-7.2 {
  execsql {
    BEGIN;
      UPDATE t7 SET b=7 WHERE a = 5;
      SELECT * FROM t7;
      SELECT * FROM t8;
    ROLLBACK;
  }
} {3 4 5 7 {after fired 3->3}}
do_test triggerC-7.3 {
  execsql {
    BEGIN;
      UPDATE t7 SET b=7 WHERE a = 1;
      SELECT * FROM t7;
      SELECT * FROM t8;
    ROLLBACK;
  }
} {3 4 5 6}

do_test triggerC-7.4 {
  execsql {
    DROP TRIGGER t7t;
    CREATE TRIGGER t7t BEFORE UPDATE ON t7 WHEN (old.rowid!=1 OR new.rowid!=8)
    BEGIN
      UPDATE t7 set rowid = 8 WHERE rowid=1;
    END;
  }
} {}
do_test triggerC-7.5 {
  execsql {
    BEGIN;
      UPDATE t7 SET b=7 WHERE a = 5;
      SELECT rowid, * FROM t7;
      SELECT * FROM t8;
    ROLLBACK;
  }
} {2 3 4 3 5 7 8 1 2 {after fired 1->8} {after fired 3->3}}
do_test triggerC-7.6 {
  execsql {
    BEGIN;
      UPDATE t7 SET b=7 WHERE a = 1;
      SELECT rowid, * FROM t7;
      SELECT * FROM t8;
    ROLLBACK;
  }
} {2 3 4 3 5 6 8 1 2 {after fired 1->8}}

do_test triggerC-7.7 {
  execsql {
    DROP TRIGGER t7t;
    DROP TRIGGER t7ta;
    CREATE TRIGGER t7t BEFORE DELETE ON t7 BEGIN
      UPDATE t7 set rowid = 8 WHERE rowid=1;
    END;
    CREATE TRIGGER t7ta AFTER DELETE ON t7 BEGIN
      INSERT INTO t8 VALUES('after fired ' || old.rowid);
    END;
  }
} {}
do_test triggerC-7.8 {
  execsql {
    BEGIN;
      DELETE FROM t7 WHERE a = 3;
      SELECT rowid, * FROM t7;
      SELECT * FROM t8;
    ROLLBACK;
  }
} {3 5 6 8 1 2 {after fired 2}}
do_test triggerC-7.9 {
  execsql {
    BEGIN;
      DELETE FROM t7 WHERE a = 1;
      SELECT rowid, * FROM t7;
      SELECT * FROM t8;
    ROLLBACK;
  }
} {2 3 4 3 5 6 8 1 2}


finish_test