How to read syntax diagrams
- Read the syntax diagrams from left to right, from top to bottom,
following the path of the line.
►►───symbol indicates the beginning of a syntax diagram.
───►symbol indicates that the syntax diagram is continued on the next line.
►───symbol indicates that the syntax diagram is continued from the previous line.
───►◄symbol indicates the end of a syntax diagram.
Diagrams of syntactical units other than complete statements start with the
►───symbol and end with the
- Required items appear on the horizontal line (the main path):
- Optional items appear below the main path:
- If you can choose from two or more items, they appear vertically,
in a stack. If you must choose one of the items, one item of the stack
appears on the main path:
If choosing one of the items is optional, the entire stack appears below the main path:
If one of the items is the default, it appears above the main path and the remaining choices are shown below:
- An arrow returning to the left, above the main line, indicates
an item that can be repeated:
If the repeat arrow contains a comma, you must separate repeated items with a comma:
- Keywords appear in uppercase (for example,
FROM). They must be spelled exactly as shown. Variables appear in lowercase italics (for example, column-name). They represent user-supplied names or values.
- If punctuation marks, parentheses, arithmetic operators, or other such symbols are shown, you must enter them as part of the syntax.