What You Should Know First

By the end of this lesson you will know exactly which skills this Tableau course expects, how to test yourself in ten minutes, and where to learn anything you are missing.

Tableau is a tool for turning tables of data into charts and dashboards. You do not need to be a programmer. But you will move much faster if a few ideas already feel normal. Think of it like learning to drive a car: you do not need to be a mechanic, but you should know the road signs.

Who this course is for

This course suits students, graduates and office staff who want to analyse data visually. It also suits people who already know Power BI or Excel charts and want to learn Tableau. It starts from your first chart and goes up to advanced calculations, so beginners and working analysts both have something to learn.

You should be comfortable with three things:

1. Working with a table of rows and columns in Excel or Google Sheets.
2. Simple arithmetic on columns: totals, averages, percentages.
3. Reading a short formula and guessing what it does.

SQL is helpful but not required. Statistics beyond averages is not needed.

Skill 1: rows, columns and tidy tables

A table stores data in rows and columns. Each row is one record, such as one bill at a shop. Each column is one property of that record, such as the date, the city or the amount. A tidy table has one heading row, one record per row and no merged cells or subtotal rows.

Tableau expects tidy tables. A school register is a good picture: one line per student, one column per detail. If someone writes "Total" in the middle of the register, the register is no longer tidy.

If you can read this table and say "two orders came from Jaipur, worth ₹1,008 together", you are ready.

Skill 2: totals, averages and percentages

Most charts in Tableau show a total, an average or a percentage. You should be able to work these out in a spreadsheet. Try this quick test in Excel with the three sales values above in cells D2 to D4.

=SUM(D2:D4)
=AVERAGE(D2:D4)
=D2/SUM(D2:D4)

1966
655.33
0.192 (format it as a percentage to see 19.2%)

The first line adds the three sales. The second line gives the average order value. The third line shows what share of the total the first order makes. If any of these felt new, spend a day on the Excel formulas lesson and basic functions first.

Skill 3: grouping and summarising

Tableau constantly answers questions like "total sales by city". That idea is called grouping: you collect rows with the same city and add up their sales. In Excel this is a PivotTable. In SQL it is GROUP BY. You do not need to write SQL for this course, but if you have seen this query, Tableau will feel familiar:

SELECT city, SUM(sales) AS total_sales
FROM orders
GROUP BY city
ORDER BY total_sales DESC;

city    | total_sales
--------+------------
Jaipur  | 1008
Lucknow | 958

Tableau writes queries like this for you when you drag fields onto a chart. Knowing what happens underneath helps you understand why a number looks the way it does. The SQL GROUP BY lesson and Excel PivotTables both teach this idea well.

A ten-minute self-test

Step 1: Open a blank Excel sheet and type the three-row table above.

Step 2: Make a PivotTable with City in Rows and Sales in Values. You should see Jaipur 1,008 and Lucknow 958.

Step 3: Add a column that shows each order as a percentage of the total. You should see 19.2%, 32.0% and 48.7%.

If all three steps worked, start the next lesson. If not, the gaps are small and the linked lessons fill them quickly.

Related courses

• Data Analytics: how analysts frame business questions before building any chart.
• Excel: the spreadsheet skills Tableau builds on.
• SQL: helpful when you connect Tableau to databases.
• Power BI: another dashboard tool; the comparison lesson explains how the two differ in approach.
• Statistics: useful later for averages, spread and trend lines.

Key points

• Tableau needs no programming, but you should be comfortable with tables, totals, averages and percentages.
• Tableau works best with tidy tables: one heading row, one record per row, no subtotal rows.
• "Total sales by city" is grouping; Tableau does it for you when you drag fields.
• SQL and Excel snippets in this course are only for checking numbers by hand.
• Use the linked courses to fill any gap before you continue.

=SUM(E2:E6)
=AVERAGE(E2:E6)
=MAX(E2:E6)/SUM(E2:E6)

1200
240
0.375