You will generally use the following three types of expressions when working with SQL statements.
|CONCATENATION||Combining two or more character columns or literals into a single character string|
|MATHEMATICAL||Adding, subtracting, multiplying, and dividing numeric columns or literals|
|DATE AND TIME ARITHMETIC||Applying addition or subtraction to dates and times|
The SQL Standard defines two sequential vertical bars as the concatenation operator. You can concatenate two character items by placing a single item on either side of the concatenation operator. The result is a single string of characters that is a combination of both items. Figure 5-5 shows the syntax diagram for the concatenation expression.