This section describes the notation conventions used in this document.
Two conventions are used to describe the SQL syntax and code:
- Syntax diagrams, used to describe SQL syntax form, including options.
- Square braces in the text, used to represent options. The indicated parentheses are required when you specify options.For example:
- DECIMAL [(n[,m])] means the decimal data type can be defined optionally as follows:
- Without specifying the precision value n or scale value m
- Specifying precision (n) only
- Specifying both values (n, m)
- You cannot specify scale without first defining precision.
- CHARACTER [(n)] means that (n) is optional.
- DECIMAL [(n[,m])] means the decimal data type can be defined optionally as follows:
The values for n and m are integers in all cases.
Symbols from the predicate calculus, set theory, and dependency theory are also used occasionally to describe logical operations. See Predicate Calculus and Set Theory Notation Used in This Document and Dependency Theory Notation Used in This Document.