PHP Fatal error: Uncaught Error: Call to a member function exec()

[Anonymous]

Trying to update data base and am getting FATAL error. Don't have a clue how to decipher the message.

<?php
// file /var/www/rickSQL.com/public_html/renoAZID/aatest00.php
// Thu Jul 9, 11:04

error_reporting (E_ALL ^ E_NOTICE);

global $db;

   class MyDB extends SQLite3 {
      function __construct() {
         $this->open('test00.db');
      }
   }
   $db = new MyDB();
   if(!$db) {
      echo $db->lastErrorMsg();
   } else {
      echo "Opened database successfully\n";
   }
  
"DROP TABLE IF EXISTS `testdata`";

$query=
"CREATE TABLE IF NOT EXISTS `testdata` (
	`Id`	INTEGER PRIMARY KEY AUTOINCREMENT,
	`Date`	TEXT NOT NULL,
	`Location`	TEXT NOT NULL,
	`Description`	TEXT NOT NULL,
	`Category`	TEXT NOT NULL,
	`Amount`	REAL
);"; 

   $ret = $db->exec($query);
   if(!$ret){
      echo $db->lastErrorMsg();
   } else {
      echo "Table created successfully\n";
   }
  

$query=
"INSERT INTO `testdata` (Date,Location,Description,Category,Amount) VALUES ('04/03/2019','419 Upper Blvd', 'Kitchen Sink And Faucet','appliances',438.5);
INSERT INTO `testdata` (Date,Location,Description,Category,Amount) VALUES ('04/21/2019','419 Upper Blvd','Refrigerator And BR Light','appliances',1567.55);
INSERT INTO `testdata` (Date,Location,Description,Category,Amount) VALUES ('05/03/2019','419 Upper Blvd','Washer Dryer','appliances',1102.1);
INSERT INTO `testdata` (Date,Location,Description,Category,Amount) VALUES ('05/17/2019','419 Upper Blvd','Kitchen Lights','appliances',113.67);
INSERT INTO `testdata` (Date,Location,Description,Category,Amount) VALUES ('04/01/2019','419 Upper Blvd','Kitchen Fixtures Stove - Ect','appliances',862.82);
INSERT INTO `testdata` (Date,Location,Description,Category,Amount) VALUES ('04/26/2019','419 Upper Blvd','House Cleanup','cleaning', 130);
INSERT INTO `testdata` (Date,Location,Description,Category,Amount) VALUES ('11/12/2018','419 Upper Blvd','Remove Wallpaper','demo', 650);
INSERT INTO `testdata` (Date,Location,Description,Category,Amount) VALUES ('11/19/2018','419 Upper Blvd','Remove Sinks And Toilets – Baths','demo',206.85);
INSERT INTO `testdata` (Date,Location,Description,Category,Amount) VALUES ('11/19/2018','419 Upper Blvd','Gas In Kitchen – Off-  Rm Lr Heater','demo',99);
INSERT INTO `testdata` (Date,Location,Description,Category,Amount) VALUES ('06/01/2019','419 Upper Blvd','Misc','tools',26.35);
INSERT INTO `testdata` (Date,Location,Description,Category,Amount) VALUES ('06/13/2019','419 Upper Blvd','Misc','tools',84.79);
INSERT INTO `testdata` (Date,Location,Description,Category,Amount) VALUES ('09/24/2019','419 Upper Blvd','Misc','tools',19.58);
INSERT INTO `testdata` (Date,Location,Description,Category,Amount) VALUES ('10/29/2019','3607 Smithfield','Service-New Rollers-Lube','maint', 208.2);
INSERT INTO `testdata` (Date,Location,Description,Category,Amount) VALUES ('03/01/2019','3607 Smithfield','Seasonal Inspection','maint',39.95);
INSERT INTO `testdata` (Date,Location,Description,Category,Amount) VALUES ('10/16/2020','3607 Smithfield','New Remote and Estimate for seals','maint',46.84);
INSERT INTO `testdata` (Date,Location,Description,Category,Amount) VALUES ('06/01/2020','419 Upper Blvd','Sprinkler Turn-on;  Backflow Test','landscape',65.0);
INSERT INTO `testdata` (Date,Location,Description,Category,Amount) VALUES ('04/10/2020','419 Upper Blvd','Fertilize & Weed Control','landscape','0.00');
INSERT INTO `testdata` (Date,Location,Description,Category,Amount) VALUES ('06/21/2020','419 Upper Blvd','Fertilize & Weed Control - paid for April also','landscape',126.0);
INSERT INTO `testdata` (Date,Location,Description,Category,Amount) VALUES ('10/16/2018','3607 Smithfield','New Remote and Estimate for seals','maint', 46.84);
";

 $ret = $db->exec($query);
   if(!$ret) {
      echo $db->lastErrorMsg();
   } else {
      echo "Records created successfully\n";
   }
//  ================================================================================================

//                                               UPDATE DATES  HERE

//  ================================================================================================ 

   $query="SELECT * FROM testdata;";
   
   $ret = $db->query($query);
      while($row = $ret->fetchArray(SQLITE3_ASSOC) ) {
      $rows[]=$row;
   }
   echo "Operation done successfully\n";

	for($i=0; $i<count($rows); $i++) {
		$val=$rows[$i]['Date'];
		$index=(int)$rows[$i]['Id']; 
		$x=explode("/",$val);                             		
		updateDb($index, $x);
		 
[b]/*		 OUTPUT INCLUDING THE ERROR MESSAGE 

Opened database successfully
Table created successfully
Records created successfully
Operation done successfully

PHP Fatal error:  Uncaught Error: Call to a member function exec() on null in /var/www/rickSQL.com/public_html/renoAZID/aatest00.php:136
Stack trace:
#0 /var/www/rickSQL.com/public_html/renoAZID/aatest00.php(84): updateDb(1, Array)
#1 {main}
  thrown in /var/www/rickSQL.com/public_html/renoAZID/aatest00.php on line 136

*/	[/b]	          
	}	

//print_r($rows); exit("Leaving Update area - Line 75\n\n");

//  ================================================================================================

     
   $query="SELECT * FROM testdata;";
   
   $ret = $db->query($query);
      while($row = $ret->fetchArray(SQLITE3_ASSOC) ) {
      $rows[]=$row;
   }
   echo "Operation done successfully after update \n";

$db->close();

print_r($rows); [b]// THIS WILL NOT RUN[/b]


//  ==============================  FUNCTIONS HERE =============================


function updateDb($index, $val) {   // update database to julian dates 

$x=gregoriantojd($val[0], $val[1], $val[2]);
		
$query="UPDATE testdata SET `Date`= ".$x." WHERE `Id`= ".$index.";";

// $query = UPDATE testdata SET `Date`= 2458577 WHERE `Id`= 1;

//exit($query.".... bye from line 131 \n\n");
	
 $ret = $db->exec($query);
   if(!$ret) {
      echo $db->lastErrorMsg();
   } else {
      echo $db->changes(), " Dates updated successfully\n";
   }
 } // update()
 
?>