Project the CITY over the CUSTOMER relation.

To project the CITY over the CUSTOMER relation, you would use SQL (Structured Query Language). Here are the steps:

1. Open your SQL database management system and connect to the database where the CUSTOMER relation (table) is stored.

2. Once you're connected to the database, you can use the SQL SELECT statement to project the CITY over the CUSTOMER relation. The SQL SELECT statement is used to fetch the data from a database table which returns this data in the form of a result table. These result tables are called result-sets.

3. The basic syntax of the SQL SELECT statement is as follows:

SELECT column1, column2, ..., columnN 
FROM table_name;

4. In your case, you want to project the CITY over the CUSTOMER relation. So, you would replace 'column1' with 'CITY' and 'table_name' with 'CUSTOMER'. The SQL statement would look like this:

SELECT CITY 
FROM CUSTOMER;

5. Run this SQL statement in your database management system. The result-set will be a table of all the cities in the CUSTOMER table.

Remember, SQL is case-insensitive, which means SELECT and select have the same meaning in SQL statements. However, it is a good programming practice to make SQL keywords uppercase to distinguish them from table and column names.