Joining on relations
You've used the following diagram in the previous exercise:
You've learned that you can use the read_sql() function from pandas to query the database. The real power of SQL is the ability to join information from multiple tables quickly. You do this by using the JOIN statement.
When joining two or more tables, pandas puts all the columns of the query result into a DataFrame.
This exercise is part of the course
Introduction to Data Engineering
Exercise instructions
- Complete the
SELECTstatement, so it joins the"Customer"with the"Order"table. - Print the
idcolumn ofdata. What do you see?
Hands-on interactive exercise
Have a go at this exercise by completing this sample code.
# Complete the SELECT statement
data = pd.read_sql("""
SELECT * FROM "Customer"
INNER JOIN "____"
ON "Order"."____"="Customer"."____"
""", db_engine)
# Show the id column of data
print(data.____)