| The following typographical conventions are used in this book: -
- Italic
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Used for emphasis, for the first use of a technical term , for example URLs, and for file and directory names . -
- Constant width
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Used for SQL examples, file contents, and examples of output. -
- Hungarian_Constant_Width
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Used for table and column names, whether in SQL or referring to SQL from within the body of a paragraph. Also used for alias names and node names , which are elements in a SQL diagram that theoretically refer to table aliases, even when a diagram sometimes shows an abstract tuning problem without referring to a specific SQL statement that corresponds to that problem. Since aliases are usually made an acronym based on a table name , such as CT for the column Code_Translations , aliases are usually pure uppercase. -
- (C, O, OT, OD, ODT, P, S, A)
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A constant-width list of aliases, node names, or columns , bounded in parentheses. I borrow this n-tuple notation from mathematics to indicate an ordered list of items. In the example case, the notation describes a join order between nodes in a join diagram, representing table aliases. In another example, (Code_Type , Code) would represent a pair of indexed columns in a two-column index, with Code_Type as the first column. Alternately, Code_Translations(Code_Type, Code) represents the same index, while specifying that it is on the table Code_Translations . -
- <Constant_Width_Italic>
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Constant-width italic text inside angle brackets describes missing portions of a SQL statement template, which you must fill in, that represents a whole class of statements. For example, SomeAlias.Leading_Indexed_Column= <Expression> represents any equality condition matching the leading column of an index with any other expression. -
- UPPERCASE
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In SQL, uppercase indicates keywords, function names, and tables or views pre-defined by the database vendor (such as Oracle's PLAN_TABLE ). Pay special attention to notes set apart from the text with the following icons:  | Indicates a general note, tip, or suggestion. For example, I sometimes use notes for asides specific to a particular database vendor, in the midst of an otherwise vendor-independent discussion. | |
 | Indicates a warning, used to point out special pitfalls I've seen relating to the current discussion. | |
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