Skip to content

07 · Filters & Parameters

Filters remove data from a view; parameters are user-adjustable values a calculated field can react to. This module covers both, building a threshold-adjustable view of the Orders table.

1. Dimension filters

  1. Drag Region from the Data pane onto the Filters shelf. A dialog lists every distinct value (Central, East, West) with checkboxes — leave all checked to filter nothing yet, or uncheck Central to exclude it from the view entirely.
  2. Once a filter is on the shelf, right-click it → Show Filter to add an interactive control (checkboxes, a dropdown, or a list, chosen from the card's own dropdown arrow) directly on the worksheet/dashboard so a viewer can change it without editing the workbook.

2. Measure filters

  1. Drag Sales onto the Filters shelf. Tableau asks which aggregation to filter on (Sum, Average, etc. — pick Sum) then presents a range slider.
  2. Set the range to, say, 500–2500. Against Orders, this excludes the two Office Supplies orders (60 and 120) and the Central Furniture Chair order stays in only if its Sales (800) falls in range — verify by listing which of the 8 orders remain: 1001 (1200), 1002 (450 — excluded, below 500), 1004 (800), 1005 (2200), 1006 (950), 1008 (1100) — so 1002, 1003, 1007 are excluded, leaving 5 orders.
  3. Measure filters apply before aggregation on the underlying rows (for a simple SUM), which matters once table calculations are layered on top (Module 8) — a measure filter and a table-calculation-based filter can behave differently because of when in Tableau's query pipeline each is applied.

3. Filter cards: context and order

  1. Right-click a filter card on the Filters shelf → Add to Context turns it into a context filter (shown with a grey background), which Tableau applies before any other filters below it in the query pipeline — relevant once you stack multiple filters and one needs to restrict the pool the others operate on (e.g. filtering to Furniture first, then a Top-N filter on Sales within just Furniture).
  2. Without context, all non-context filters apply independently at roughly the same stage — for this course's small dataset the distinction rarely changes the visible result, but it's worth knowing before Level 2's larger, multi-filter dashboards.

4. Parameters

  1. In the Data pane dropdown, choose Create Parameter.... Name it Sales Threshold, set Data type to Float, and set a default Current value of 500.
  2. Right-click the new parameter in the Data pane (under a separate Parameters section, bottom of the pane) → Show Parameter Control to place an adjustable slider/input on the worksheet.

  3. Create a calculated field Above Threshold that reacts to the parameter:

    SUM([Sales]) >= [Sales Threshold]

  4. Drag Order ID to Rows and Above Threshold to Color. With the parameter at its default 500, verify by hand against Orders: orders 1001, 1004, 1005, 1006, 1008 (Sales ≥ 500) should color as TRUE; 1002, 1003, 1007 as FALSE.

  5. Move the parameter control's slider to 1000 and watch the coloring update live — now only 1001, 1005, 1006, 1008 should read TRUE (950 ≥ 1000 is false, so 1006 flips to FALSE) — confirming the calculated field re-evaluates against the live parameter value rather than a fixed number.

5. Filters vs. parameters — when to use which

  • A filter changes what data is included in the view — it can remove marks entirely.
  • A parameter is a single stored value a calculated field, a filter's condition, or even an axis reference line can react to — it never removes data on its own; whatever formula reads it decides what to do with the value.
  • Use a parameter when you want one control to drive several things at once (a threshold used in both a calculated field's color logic and a reference line), which a plain filter can't do since a filter's job is narrowly "include or exclude."

How It Actually Works

Filters and parameters sit at different points in VizQL's query pipeline, which is the real reason they behave so differently:

  1. A dimension filter (Region) becomes a WHERE Region IN ('East', 'West')-style clause added to the generated query before aggregation — it physically removes rows from what the database or Hyper engine ever sums, which is why an excluded region's Sales can't leak into any total on that sheet.
  2. A measure filter (Sales, Sum, 500–2500) is applied after aggregation for a per-row measure filter on a non-aggregated field, but here — filtering on SUM(Sales) — Tableau generates something like HAVING SUM(Sales) BETWEEN 500 AND 2500 when a GROUP BY is present, or filters the raw column pre-aggregation when there's no grouping context; Section 2's note about table calculations matters precisely because a table calc-based filter runs in a third, later stage (after the query returns), so it can only ever filter marks already computed — it can never reduce what a SUM upstream saw.
  3. Context filters (Section 3) map to query pipeline ordering: a context filter's WHERE/subquery clause is materialized first, and every other filter's clause is then applied against that already-narrowed result set — mechanically equivalent to nesting a nested subquery: SELECT ... FROM (SELECT ... WHERE <context filter>) WHERE <other filters>. This is why a context filter can change a Top-N filter's result: the Top-N is now computed only over rows the context filter already let through.
  4. A parameter never appears in a WHERE/GROUP BY clause directly — it's a stored scalar value substituted as a literal into whatever formula references it at query-generation time. Above Threshold compiles (conceptually) to SUM(Sales) > 950 with 950 substituted in from the parameter's current value; change the parameter and Tableau regenerates every dependent query with the new literal, re-running them — never touching stored data, since parameters are pure client-side query inputs. Hand-check at exactly 950: Order 1006 (Sales 950) evaluates 950 > 950 = FALSE, so it reads FALSE, not TRUE — the boundary is strict greater-than, not greater-or-equal, unless the formula explicitly uses >=.

Cheat sheet

Action How
Filter a dimension Drag field to Filters shelf → pick values
Filter a measure Drag field to Filters shelf → pick aggregation → range
Show a filter control Right-click filter card → Show Filter
Make a context filter Right-click filter card → Add to Context
Create a parameter Data pane dropdown → Create Parameter...
Show a parameter control Right-click parameter → Show Parameter Control
Reference a parameter in a formula Use its name in brackets, e.g. [Sales Threshold]

Exercise

Build the Sales Threshold parameter and Above Threshold calculated field as described. Then set the parameter to exactly 950 and, by hand from the Orders table, list every Order ID that should read TRUE — including correctly handling the boundary case of an order whose Sales exactly equals 950.