In the relational model of databases, a primary key is a designated attribute (column) that can reliably identify and distinguish between each individual...
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A foreign key is a set of attributes in a table that refers to the primary key of another table, linking these two tables. In the context of relational...
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but only one of them is used as the primary key of the relation. The remaining candidate keys are called unique keys because they can uniquely identify...
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primary key firstName + lastName for students is a composite key. Relational database Alternate key Candidate key Foreign key Primary key Unique key Superkey...
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Relational database (section Primary key)
have a unique primary key (PK) for each row in a table. When a new row is written to the table, a new unique value for the primary key is generated; this...
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attributes. Specific candidate keys are sometimes called primary keys, secondary keys or alternate keys. The columns in a candidate key are called prime attributes...
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world and the primary key of the database. In this case the surrogate may be used as a primary key, resulting in the term surrogate key. In a temporal...
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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...
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dbm manages associative arrays of arbitrary data by use of a single key (a primary key). Modern implementations include sdbm, GNU dbm, and Berkeley DB. Although...
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are generally assigned a surrogate key to ensure each row can be uniquely identified. This key is a simple primary key. Dimension tables usually have a...
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foreign key can only contain either null values or values from a parent table's primary key or a candidate key. In other words, when a foreign key value...
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it must use a foreign key in conjunction with its attributes to create a primary key. The foreign key is typically a primary key of an entity it is related...
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Extract, transform, load (section Uniqueness of keys)
foreign key is a column in another table that refers to a primary key. Keys can comprise several columns, in which case they are composite keys. In many...
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concerns the concept of a primary key. Entity integrity is an integrity rule which states that every table must have a primary key and that the column or...
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Database index (section Primary index)
used to police database constraints, such as UNIQUE, EXCLUSION, PRIMARY KEY and FOREIGN KEY. An index may be declared as UNIQUE, which creates an implicit...
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between entities is implemented by storing the primary key of one entity as a pointer or "foreign key" in the table of another entity. There is a tradition...
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[column name] [data type] {NULL | NOT NULL} {column options} Primary key definition: PRIMARY KEY ( [comma separated column list] ) Constraints: {CONSTRAINT}...
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rather of the relationship itself. One-to-many often refer to a primary key to foreign key relationship between two tables, where the record in the first...
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concerned with ensuring that each row of a table has a unique and non-null primary key value; this is the same as saying that each row in a table represents...
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tables together by referencing the primary keys (PK) of each data table. In effect, it contains a number of foreign keys (FK), each in a many-to-one relationship...
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designated as a primary key by which the rows of the table could be uniquely identified; cross-references between tables always used these primary keys, rather...
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A natural key (also known as business key or domain key) is a type of unique key in a database formed of attributes that exist and are used in the external...
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component of a table's primary key is the partition key; within a partition, rows are clustered by the remaining columns of the key. Other columns may be...
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non-autoincrementing Integer Primary Keys.[failed verification] Version 3.6.19 released on October 14, 2009 added support for foreign key constraints. Stored procedures...
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Record (computer science) (section Key field)
can then be retrieved using a primary key. The tables themselves are also records which may have a foreign key: a key that references data in another...
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database invariant is referential integrity, which guarantees the primary key–foreign key relationship. Transactions are often executed concurrently (e.g...
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California a key player in 2008 – CNN.com". Cnn.com. Retrieved September 15, 2008. "Newhouse News Service – Giuliani Eyes Winner-Take-All Primaries". Newhouse...
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"key fields". A "primary key" assigns a field to its "special order table". For example, the "Doctor Last Name" field might be assigned as a primary key...
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