diff --git a/src/data/courses/sql/chapters/sql-basics/lessons/selecting-distinct-values.md b/src/data/courses/sql/chapters/sql-basics/lessons/selecting-distinct-values.md new file mode 100644 index 000000000..6fbe6a973 --- /dev/null +++ b/src/data/courses/sql/chapters/sql-basics/lessons/selecting-distinct-values.md @@ -0,0 +1,53 @@ +--- +title: Selecting DISTINCT Values +description: Learn the basics of SQL, the language for querying databases. +order: 120 +type: lesson-challenge +--- + +We can use the `DISTINCT` keyword in our `SELECT` statement to select the unique values of a column. + +Continuing the same example of an online bookstore, let's say we have a table called `orders` that contains the information about the orders placed by customers. + +Let's say we have the following data in the `orders` table: + +| id | customer_id | order_date | status | +|----|-------------|------------|--------| +| 1 | 101 | 2024-01-01 | completed | +| 2 | 102 | 2024-01-02 | pending | +| 3 | 101 | 2024-01-03 | completed | +| 4 | 103 | 2024-01-04 | cancelled | +| 5 | 102 | 2024-01-05 | completed | + +The `status` column contains the status of the orders. We want to select the distinct values of the `status` column. + +The SQL query to do this would be: + +```sql +SELECT DISTINCT status +FROM orders; +``` + +This will return the following result: + +| status | +|--------| +| completed | +| pending | +| cancelled | + +--- + +## Challenge + +Given the same `orders` table, i.e. + +| id | customer_id | order_date | status | +|----|-------------|------------|--------| +| 1 | 101 | 2024-01-01 | completed | +| 2 | 102 | 2024-01-02 | pending | +| 3 | 101 | 2024-01-03 | completed | +| 4 | 103 | 2024-01-04 | cancelled | +| 5 | 102 | 2024-01-05 | completed | + +Write an SQL query to select the distinct values of the `order_date` for us to see the unique dates on which orders were placed. \ No newline at end of file