What are the various brackets, such as {},,[], used in database syntax?

< > angle brackets, which are used to delimit strings, the string is the name of the syntax element, and the non-terminator of the SQL language.

:: = defines the operator. Used in the build rule, separates the elements and rule definitions defined by the rule. The defined element is on the left side of the operator and the rule definition is on the right side of the operator.

[] square brackets represent optional elements in the rule. The rules section in square brackets can be explicitly specified or omitted.

{} curly braces gather elements in the rule. The rules section in curly braces must be explicitly specified.

| The replace operator. The vertical bar indicates that the part of the rule after the vertical bar is replaceable for the part before the vertical bar. If the vertical bar appears in a position other than curly braces or square brackets, it specifies a complete replacement for the element defined by the rule. If the vertical bar appears in curly brackets or square brackets, it specifies a brace pair or square brackets to replace the innermost contents.

. . . An ellipsis indicates that the element that is applied to the ellipsis in the rule may be repeated several times. If the ellipsis immediately follows the closing curly brace "}", it is applied to the rule part between the closed curly brace and the bloom brace "{". If the ellipsis appears after any other element, it is applied only to that element.

!!
--Close MSSQ

What are the various brackets, such as {},,[], used in database syntax?