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The active record pattern is an approach to accessing data in a database. A database table or view is wrapped into a class. Thus, an object instance is tied to a single row in the table. After creation of an object, a new row is added to the table upon save. Any object loaded gets its information from the database.
Some database implementations adopted the term upsert (a portmanteau of update and insert) to a database statement, or combination of statements, that inserts a record to a table in a database if the record does not exist or, if the record already exists, updates the existing record.
A current version is maintained for the table, or possibly a group of tables. This is stored in a supporting construct such as a reference table. When a change capture occurs, all data with the latest version number is considered to have changed. Once the change capture is complete, the reference table is updated with a new version number.
New tuples can supply explicit values or be derived from a query. Similarly, queries identify tuples for updating or deleting. Tuples by definition are unique. If the tuple contains a candidate or primary key then obviously it is unique; however, a primary key need not be defined for a row or record to be a tuple. The definition of a tuple ...
For example, a company can create a time plot that shows its costs and revenues over a certain period. The data can then be arranged to show per day, month, quarter, year, etc. This requires simple formatting tools so the data can quickly be changed and compared. Power BI allows the user to customize their visualizations by adding colors and ...
The U.S. made the Gadsden Purchase in 1853 to acquire a nearly 30,000 square-mile region of present-day southern Arizona and southwestern New Mexico in a treaty signed by the American ambassador ...
For this example it is assumed that each book has only one author. A table that conforms to the relational model has a primary key which uniquely identifies a row. In our example, the primary key is a composite key of {Title, Format} (indicated by the underlining):
A common stomach bug is surging, according to new data from the US Centers for Disease Control and Prevention.. In the week of December 5, there were 91 outbreaks of norovirus reported, up from 69 ...