Chapter 8

How to work with data types and functions

Exercises

1. Write a SELECT statement that returns these columns from the Invoices table:

The invoice_total column

Use the TO_CHAR function to return the invoice_total column with 2 digits to the right of the decimal point.

Use the TO_CHAR function to return the invoice_total column with no digits to the right of the decimal point and no decimal point

Use the CAST function to return the invoice_total column as an integer with seven digits

2. Write a SELECT statement that returns these columns from the Invoices table:

The invoice_date column

Use the TO_CHAR function to return the invoice_date column with its full date and time including a four-digit year on a 24-hour clock

Use the TO_CHAR function to return the invoice_date column with its full date and time including a four-digit year on a 12-hour clock with an am/pm indicator

Use the CAST function to return the invoice_date column as VARCHAR2(10)

3. Write a SELECT statement that returns these columns from the Vendors table:

The vendor_name column

The vendor_name column in all capital letters

The vendor_phone column

The last four digits of each phone number

When you get that working right, add the columns that follow to the result set. This is more difficult because these columns require the use of functions within functions.

The second word in each vendor name if there is one; otherwise, blanks

The vendor_phone column with the parts of the number separated by dots as in 555.555.5555

4. Write a SELECT statement that returns these columns from the Invoices table:

The invoice_number column

The invoice_date column

The invoice_date column plus 30 days

The payment_date column

A column named days_to_pay that shows the number of days between the invoice date and the payment date

The number of the invoice_dates month

The four-digit year of the invoice_date

The last day of the invoice dates month

When youve got this working, add a WHERE clause that retrieves just the invoices for the month of May based on the invoice date, not the number of the invoice month.

5. Write a SELECT statement that returns these columns from the Invoices table:

The invoice_number column

The balance due (invoice total minus payment total minus credit total) with commas, a decimal point, and two decimal positions

A column named Balance Rank that uses the RANK function to return a column that ranks the balance due in descending order.