The syntactical elements of the SQL language are called tokens. Tokens are divided into two types:
These are numeric constants, ordinary identifiers, or keywords. Ordinary tokens cannot include spaces, and must be followed by either delimiter tokens or spaces.
These are string constants, delimited identifiers, operators (=, <=, <, >=, >, !=, ^=), or special characters identified in command syntax.
When a command extends to more than one line, tokens cannot be broken in the middle.