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Like we used the fetch methods, we can also use a for loop to retrieve data. The following code will iterate through each row in the students table and print each row where the Grade field is 'Pass'.

for row in cursor.execute('''SELECT * FROM students WHERE Grade = 'Pass';'''): print(row)

You can also use a for loop to iterate through a table field and calculate a measurement.

# save all rows from a field with .fetchall() then use a for loop to find some sort of result.` major_codes = cursor.execute("SELECT major_code FROM students;").fetchall() # Obtain the average of the tuple list by using for loops sum = 0 for num in major_codes: sum = sum + num[0] average = sum / len(major_codes) # Show average print(average)

Let’s walk through this example code:

  • We used a SQL statement to retrieve the major code field from the students table.
  • We created the variable sum initialized at 0, to sum up the total values in the data.
  • We used a for loop to iterate through every number in major_code to create the mean average major_code.
  • We add num[0] to sum at each iteration. Note that num is a tuple of length 1 (such as (12,)) so num[0] will allow us to access the actual integer.
  • We find the average by dividing sum and the length of major_codes.

Instructions

1.

The module sqlite3, connection object, cursor object are already in your text editor. The object age, which is also in your text editor, includes a list of every age from the passengers of the titanic data table.

Create a variable called sum, set it equal to zero. You will use this to sum all passengers below the age of 18.

2.

Create a for loop that iterates through each age in the Age tuple and counts the number of people who were younger than 18. In your for loop, you should:

  • Use an if statement to check if each age within age is less than 18 years old.
  • Increment sum by one each time there is a passenger less than 18 years old.

When your for loop is complete, print sum to see the results.

Check out the Advanced Tip in the hint below to learn more about pulling and analyzing SQLite data!

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