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Once the keys are decided it is possible to define them in the system using constraints along with field value validation.) for retrieving column values from the current row. For maximum portability, result set columns within each row should be read in left-to-right order, and each column should be read only once.The option to use a string as opposed to an integer is designed to be used when column aliases and names are used in the SQL query that generated the result set.For columns that are ) it is best to use column numbers.These composite variables have internal components that you can treat as individual variables.You can pass composite variables to subprograms as a parameters.Sometimes it will make sense to have the closing parenthesis on a new line at the same character position as its opening partner—this is especially true where you have nested subqueries.
This chapter explains how to create and use PL/SQL collection and record variables.It is certainly more succinct where Celko’s book contains anecdotes and reasoning behind each rule as thoughtful prose.It is easy to include this guide in Markdown format as a part of a project’s code base or reference it here for anyone on the project to freely read—much harder with a physical book.It is a reasoned and considered balancing act to be performed at the definition of a database.Should requirements evolve in the future it is possible to make changes to the definitions to keep them up to date.If column names are used, the developer should guarantee that they uniquely refer to the intended columns by using column aliases.A column alias effectively renames the column of a result set.These guidelines are designed to be compatible with Joe Celko’s SQL Programming Style book to make adoption for teams who have already read that book easier.This guide is a little more opinionated in some areas and in others a little more relaxed.You can use this set of guidelines, fork them or make your own - the key here is that you pick a style and stick to it.To suggest changes or fix bugs please open an issue or pull request on Git Hub.