SQLite

    ** to some other UNIQUE constraint is FAIL or IGNORE, then we need
    ** to defer the running of the rowid conflict checking until after
    ** the UNIQUE constraints have run.
    */
    if( onError==OE_Replace      /* IPK rule is REPLACE */
     && onError!=overrideError   /* Rules for other constraints are different */
     && pTab->pIndex             /* There exist other constraints */
     && !upsertIpkDelay          /* IPK check already deferred by UPSERT */
    ){
      ipkTop = sqlite3VdbeAddOp0(v, OP_Goto)+1;
      VdbeComment((v, "defer IPK REPLACE until last"));
    }

    if( isUpdate ){
      /* pkChng!=0 does not mean that the rowid has changed, only that

    }
  }

  /* If the IPK constraint is a REPLACE, run it last */
  if( ipkTop ){
    sqlite3VdbeGoto(v, ipkTop);
    VdbeComment((v, "Do IPK REPLACE"));
    assert( ipkBottom>0 );
    sqlite3VdbeJumpHere(v, ipkBottom);
  }

  /* Recheck all uniqueness constraints after replace triggers have run */
  testcase( regTrigCnt!=0 && nReplaceTrig==0 );
  assert( regTrigCnt!=0 || nReplaceTrig==0 );
  if( nReplaceTrig ){

# 2019-12-26 ticket 7c13db5c3bf74001
reset_db
do_catchsql_test upsert1-1000 {
  CREATE TABLE t0(c0 PRIMARY KEY, c1, c2 UNIQUE) WITHOUT ROWID;
  INSERT OR FAIL INTO t0(c2) VALUES (0), (NULL)
    ON CONFLICT(c2) DO UPDATE SET c1 = c0;
} {1 {NOT NULL constraint failed: t0.c0}}

# 2021-12-29 forum post https://sqlite.org/forum/forumpost/06b16b8b29f8c8c3
# By Jingzhou Fu. When there is both an INTEGER PRIMARY KEY ON CONFLICT REPLACE
# and an upsert on a constraint other than the INTEGER PRIMARY KEY, the
# constraint checking logic generates invalid bytecode which might result
# in a NULL pointer dereference.
#
reset_db
do_execsql_test upsert1-1100 {
  CREATE TABLE t1(a INTEGER PRIMARY KEY ON CONFLICT REPLACE, b UNIQUE);
  INSERT INTO t1(b) VALUES(22);
  INSERT INTO t1 VALUES(2,22) ON CONFLICT (b) DO NOTHING;
  SELECT * FROM t1;
} {1 22}

finish_test