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<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Web SQL DELETE by condition</title>
  <style>
    body { font-family: system-ui, sans-serif; margin: 1.5rem; line-height: 1.5; }
    button { margin-right: 0.5rem; margin-bottom: 0.5rem; padding: 0.5rem 0.9rem; cursor: pointer; }
    #status { margin-top: 1rem; }
  </style>
</head>
<body>
  <h1>Delete by condition</h1>
  <p>Seed tasks, then remove every row where <code>done = 1</code>.</p>

  <button type="button" id="seedBtn" disabled>Seed tasks</button>
  <button type="button" id="clearDoneBtn" disabled>Delete completed</button>
  <button type="button" id="listBtn" disabled>List remaining</button>

  <p id="status">Checking Web SQL&hellip;</p>

  <script>
    var statusEl = document.getElementById('status');

    if (!window.openDatabase) {
      statusEl.textContent = 'Web SQL is not available in this browser.';
    } else {
      var db = openDatabase('tryitWsqlDeleteWhere', '1.0', 'Try It', 1024 * 1024);

      db.transaction(function (tx) {
        tx.executeSql(
          'CREATE TABLE IF NOT EXISTS tasks (id INTEGER PRIMARY KEY, title TEXT, done INTEGER)'
        );
      }, null, function () {
        statusEl.textContent = 'Ready.';
        document.getElementById('seedBtn').disabled = false;
        document.getElementById('clearDoneBtn').disabled = false;
        document.getElementById('listBtn').disabled = false;
      });

      document.getElementById('seedBtn').addEventListener('click', function () {
        db.transaction(function (tx) {
          tx.executeSql('DELETE FROM tasks');
          tx.executeSql('INSERT INTO tasks (id, title, done) VALUES (?, ?, ?)', [1, 'Write docs', 1]);
          tx.executeSql('INSERT INTO tasks (id, title, done) VALUES (?, ?, ?)', [2, 'Ship feature', 0]);
          tx.executeSql('INSERT INTO tasks (id, title, done) VALUES (?, ?, ?)', [3, 'Fix bug', 1]);
        }, null, function () {
          statusEl.textContent = 'Seeded 3 tasks (2 done, 1 open).';
        });
      });

      document.getElementById('clearDoneBtn').addEventListener('click', function () {
        db.transaction(function (tx) {
          tx.executeSql(
            'DELETE FROM tasks WHERE done = ?',
            [1],
            function (tx, result) {
              statusEl.textContent = 'Removed ' + result.rowsAffected + ' completed task(s).';
            }
          );
        });
      });

      document.getElementById('listBtn').addEventListener('click', function () {
        db.transaction(function (tx) {
          tx.executeSql(
            'SELECT title, done FROM tasks ORDER BY id',
            [],
            function (tx, result) {
              if (result.rows.length === 0) {
                statusEl.textContent = 'No tasks left.';
                return;
              }
              var parts = [];
              for (var i = 0; i < result.rows.length; i++) {
                var row = result.rows.item(i);
                parts.push(row.title + (row.done ? ' (done)' : ' (open)'));
              }
              statusEl.textContent = 'Remaining: ' + parts.join(', ');
            }
          );
        });
      });
    }
  </script>
</body>
</html>
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Web SQL DELETE — Delete by Condition
