HTML Code
<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Web SQL Update Example</title>
  <style>
    body {
      font-family: system-ui, sans-serif;
      margin: 0;
      padding: 1.5rem;
      background: #f8fafc;
      color: #334155;
      line-height: 1.6;
    }
    h1 { margin: 0 0 0.75rem; font-size: 1.25rem; color: #0f172a; }
    button {
      padding: 0.6rem 1.1rem;
      font-size: 0.9375rem;
      background: #2563eb;
      color: #fff;
      border: none;
      border-radius: 8px;
      cursor: pointer;
      margin-right: 0.5rem;
      margin-bottom: 0.5rem;
    }
    button.secondary { background: #64748b; }
    button:hover { filter: brightness(1.05); }
    #status {
      margin-top: 1rem;
      padding: 0.75rem 1rem;
      max-width: 460px;
      background: #fff;
      border: 1px solid #e2e8f0;
      border-radius: 8px;
      font-size: 0.875rem;
      min-height: 1.5rem;
    }
    #status.ok { border-left: 4px solid #22c55e; }
    #status.err { border-left: 4px solid #ef4444; }
  </style>
</head>
<body>
  <h1>Web SQL Update Example</h1>
  <button type="button" id="addRecord">Add Record</button>
  <button type="button" id="updateRecord" class="secondary">Update Record</button>
  <p id="status">Click Add Record, then Update Record.</p>

  <script>
    if (!window.openDatabase) {
      document.getElementById('status').textContent =
        'Web SQL is not supported in this browser.';
    } else {
      var db = openDatabase('myDatabase', '1.0', 'Test DB', 2 * 1024 * 1024);
      var statusEl = document.getElementById('status');

      db.transaction(function (tx) {
        tx.executeSql(
          'CREATE TABLE IF NOT EXISTS users (id INTEGER PRIMARY KEY, name TEXT, age INTEGER)'
        );
      });

      document.getElementById('addRecord').addEventListener('click', function () {
        db.transaction(function (tx) {
          tx.executeSql(
            'INSERT OR REPLACE INTO users (id, name, age) VALUES (?, ?, ?)',
            [1, 'John Doe', 25],
            function () {
              statusEl.textContent = 'Added John Doe';
              statusEl.className = 'ok';
            },
            function (tx, error) {
              statusEl.textContent = 'Error: ' + error.message;
              statusEl.className = 'err';
              return true;
            }
          );
        });
      });

      document.getElementById('updateRecord').addEventListener('click', function () {
        updateRecord(1, 'Jane Doe', 26);
      });

      function updateRecord(id, newName, newAge) {
        db.transaction(function (tx) {
          tx.executeSql(
            'UPDATE users SET name = ?, age = ? WHERE id = ?',
            [newName, newAge, id],
            function (tx, result) {
              statusEl.textContent =
                result.rowsAffected
                  ? 'Updated to ' + newName
                  : 'No row found — add a record first';
              statusEl.className = result.rowsAffected ? 'ok' : 'err';
            },
            function (tx, error) {
              statusEl.textContent = 'Error: ' + error.message;
              statusEl.className = 'err';
              return true;
            }
          );
        });
      }
    }
  </script>
</body>
</html>
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Web SQL UPDATE — Complete HTML Page (Add + Update)
