Data Manipulation Language
Completion requirements
Read this chapter and take notes on the purpose and use of the clause SELECT and how the INSERT and DELETE statements are used to make changes to data. Also, note how functions are used in these statements.
Joining Tables
Joining two or more tables is the process of comparing the data in specified columns and using the comparison results to form a new table from the rows that qualify. A join statement:
- Specifies a column from each table
- Compares the values in those columns row by row
- Combines rows with qualifying values into a new row
Although the comparison is usually for equality – values that match exactly – other types of joins can also be specified. All the different joins such as inner, left (outer), right (outer), and cross join will be described below.