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  <title>Web SQL — delete by condition</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 0.5rem; font-size: 1.25rem; color: #0f172a; }
    p { margin: 0 0 1rem; max-width: 460px; }
    .btns { display: flex; flex-wrap: wrap; gap: 0.5rem; margin-bottom: 1rem; }
    button {
      padding: 0.55rem 1rem;
      font-size: 0.9375rem;
      background: #2563eb;
      color: #fff;
      border: none;
      border-radius: 8px;
      cursor: pointer;
    }
    button.danger { background: #dc2626; }
    button:hover { filter: brightness(1.05); }
    table {
      border-collapse: collapse;
      width: 100%;
      max-width: 460px;
      background: #fff;
      border: 1px solid #e2e8f0;
      border-radius: 8px;
      overflow: hidden;
      font-size: 0.875rem;
    }
    th, td { text-align: left; padding: 0.5rem 0.75rem; border-bottom: 1px solid #e2e8f0; }
    th { background: #f1f5f9; }
    tr:last-child td { border-bottom: none; }
    .done { color: #16a34a; font-weight: 600; }
    .pending { color: #64748b; }
    #status {
      margin-top: 1rem;
      padding: 0.75rem 1rem;
      max-width: 460px;
      background: #fff;
      border: 1px solid #e2e8f0;
      border-radius: 8px;
      font-size: 0.875rem;
    }
    #status.ok { border-left: 4px solid #22c55e; }
    #status.err { border-left: 4px solid #ef4444; }
    code { background: #e2e8f0; padding: 0.1rem 0.35rem; border-radius: 4px; }
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</head>
<body>
  <h1>Delete completed tasks</h1>
  <p>Seed a small <code>tasks</code> table with a <code>done</code> flag, then run <code>DELETE FROM tasks WHERE done = ?</code> to clear everything marked complete.</p>

  <div class="btns">
    <button type="button" id="seedBtn">1. Seed Tasks</button>
    <button type="button" id="listBtn">2. List Tasks</button>
    <button type="button" id="deleteBtn" class="danger">3. Delete Completed (done = 1)</button>
  </div>

  <table id="taskTable">
    <thead>
      <tr><th>id</th><th>title</th><th>done</th></tr>
    </thead>
    <tbody id="taskBody">
      <tr><td colspan="3">Click "List Tasks" after seeding.</td></tr>
    </tbody>
  </table>

  <p id="status">Follow the steps in order.</p>

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

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

      db.transaction(function (tx) {
        tx.executeSql(
          'CREATE TABLE IF NOT EXISTS tasks (id INTEGER PRIMARY KEY, title TEXT, done INTEGER)'
        );
      });

      function renderRows(rows) {
        if (!rows.length) {
          bodyEl.innerHTML = '<tr><td colspan="3">No tasks — seed first.</td></tr>';
          return;
        }
        bodyEl.innerHTML = rows.map(function (r) {
          return '<tr><td>' + r.id + '</td><td>' + r.title + '</td><td class="' +
            (r.done ? 'done">Yes' : 'pending">No') + '</td></tr>';
        }).join('');
      }

      document.getElementById('seedBtn').addEventListener('click', function () {
        db.transaction(function (tx) {
          tx.executeSql('DELETE FROM tasks');
          [
            [1, 'Write report', 1],
            [2, 'Review pull request', 1],
            [3, 'Plan sprint', 0],
            [4, 'Fix login bug', 1],
            [5, 'Update docs', 0]
          ].forEach(function (row) {
            tx.executeSql('INSERT INTO tasks (id, title, done) VALUES (?, ?, ?)', row);
          });
        }, null, function () {
          statusEl.textContent = 'Seeded 5 tasks (3 done, 2 pending).';
          statusEl.className = 'ok';
        });
      });

      document.getElementById('listBtn').addEventListener('click', function () {
        db.transaction(function (tx) {
          tx.executeSql('SELECT id, title, done FROM tasks ORDER BY id', [], function (tx, result) {
            var rows = [];
            for (var i = 0; i < result.rows.length; i++) rows.push(result.rows.item(i));
            renderRows(rows);
          });
        });
      });

      document.getElementById('deleteBtn').addEventListener('click', function () {
        db.transaction(function (tx) {
          tx.executeSql(
            'DELETE FROM tasks WHERE done = ?',
            [1],
            function (tx, result) {
              statusEl.textContent = 'Cleared ' + result.rowsAffected + ' completed task(s).';
              statusEl.className = 'ok';
              document.getElementById('listBtn').click();
            },
            function (tx, error) {
              statusEl.textContent = 'Error: ' + error.message;
              statusEl.className = 'err';
              return true;
            }
          );
        });
      });
    }
  </script>
</body>
</html>
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Web SQL DELETE — Delete by Condition (done = 1)
