Lesson 4.1

Counting Rows with SQL COUNT

COUNT is the first aggregate most SQL learners need: it answers how many.

Aggregate functions summarize many rows into fewer rows. COUNT answers a simple but common question: how many rows are there?

count(*) counts every row. count(column_name) only counts rows where that column has a value.

Pick the count that matches the question

Use count(*) when the question is about rows. Use count(column) when the question is about known values in one column. That difference matters whenever a column can be null.

Pattern

select count(*) as total_rows,
       count(nullable_column) as rows_with_value
from table_name

Ready to run it?

Open the DuckDB playground with the matching dataset and query already filled in.

Try COUNT rows in the playground

Syntax reference

Need syntax details? See the SQL aggregate function reference

Schema · Garden Shop Table · orders 6 columns · 24 rows

Table · orders

One row per order. Unshipped orders have a null shipped_date.

6 columns · 24 rows

order_id int customer_id int order_date date shipped_date date status text coupon_code text

Your task

Return one summary row showing the total number of orders as total_orders and the number of orders where shipped date is present as orders_with_ship_date.