Keywords   All SQL keywords appear in uppercase, like the SQL statement ALTER TABLE in the following example:

ALTER TABLE [ owner.]table-name

Placeholders   Items that must be replaced with appropriate identifiers or expressions appear in italics, like the words owner and table-name in the following example:

ALTER TABLE [ owner.]table-name

Clause order   If the order of optional clauses is significant in SQL statement syntax, the clauses are listed in the main body of the syntax in the order in which they should be listed, similar to the following:

CREATE SYNCHRONIZATION SUBSCRIPTION [ subscription-name ]
TO publication-name
[ FOR ml-username, ...  ]
...

In the case where the order of optional clauses is not significant in SQL statement syntax, the clauses are listed separately like a list of options, similar to the following:

CREATE  [ OR REPLACE ] SPATIAL REFERENCE SYSTEM  
srs-name
[ srs-attribute [  srs-attribute ... ]

srs-attribute : 
IDENTIFIED BY srs-id
| DEFINITION { definition-string | NULL }
...

Optional portions   Optional portions of a statement are enclosed by square brackets. For example:

RELEASE SAVEPOINT [ savepoint-name ]

These square brackets indicate that the savepoint-name is optional. The square brackets should not be typed.

You might also see square brackets around a portions of keywords. For example, the following syntax indicates that you can use either COMMIT TRAN or COMMIT TRANSACTION:

COMMIT TRAN[SACTION] ...

Likewise, the following syntax indicates that you can use either COMMIT or COMMIT WORK:

COMMIT [ WORK ]

Repeating items   An item that can be repeated is followed by the appropriate list separator and an ellipsis (three dots), like column-constraint in the following example:

ADD column-definition [ column-constraint, ... ]

In this case, you can specify no column constraint, one, or more. If more than one is specified, they must be separated by commas.

Options   When none or only one of a list of items can be chosen, vertical bars separate the items and the list is enclosed in square brackets.

[ ASC | DESC ]

For example, you can choose one of ASC, DESC, or neither. The square brackets should not be typed.

Alternatives   When precisely one of the options must be chosen, the alternatives are enclosed in curly braces.

[ QUOTES { ON | OFF } ]

In this case, if the QUOTES option is chosen, one of ON or OFF must be provided. The brackets and braces should not be typed.