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In the relational model of databases, a primary key is a designated attribute that can reliably identify and distinguish between each individual record in a table.The database creator can choose an existing unique attribute or combination of attributes from the table (a natural key) to act as its primary key, or create a new attribute containing a unique ID that exists solely for this purpose ...
F: — First network drive if using Novell NetWare. G: — "Google Drive File Stream" if using Google Drive. H: — "Home" directory on a network server. L: — Dynamically assigned load drive under Concurrent DOS, Multiuser DOS, System Manager and REAL/32. [6] [7] M: — Drive letter for optionally memory drive MDISK under Concurrent DOS. [6]
Using compound keys—such as prefixing timestamps with sensor identifiers—can distribute this load. [1] An example could be a partition for all rows where the "zipcode" column has a value between 70000 and 79999. List partitioning: a partition is assigned a list of values. If the partitioning key has one of these values, the partition is chosen.
Conjunctive queries without distinguished variables are called boolean conjunctive queries.Conjunctive queries where all variables are distinguished (and no variables are bound) are called equi-join queries, [1] because they are the equivalent, in the relational calculus, of the equi-join queries in the relational algebra (when selecting all columns of the result).
convert is an external command first introduced with Windows 2000. [2] If the drive cannot be locked (for example, the drive is the system volume or the current drive) the command gives the option to convert the drive the next time the computer is restarted.
Such a condition results in the standby being behind the primary. [5] This can be overcome, using Oracle’ Active Data Guard Farsync technology. The same release of Oracle Database Enterprise Edition must be installed on the primary database and all standby databases, except during rolling database upgrades using logical standby databases.
A logical disk, logical volume or virtual disk (VD [1] or vdisk [2] for short) is a virtual device that provides an area of usable storage capacity on one or more physical disk drive(s) in a computer system. The disk is described as logical or virtual because it does not actually exist as a single physical entity in its own right. The goal of ...
Common examples of DDL statements include CREATE, ALTER, and DROP. If you see a .ddl file, that means the file contains a statement to create a table. Oracle SQL Developer contains the ability to export from an ERD generated with Data Modeler to either a .sql file or a .ddl file.