what are the three characteristics of an ideal primary key?
606515
The three characteristics of an ideal primary key are short, numeric and fixed.
1351338
['every column in a row must be single valued. ... ', 'primary keys cannot be null. ... ', 'foreign keys, if not null, must have values that correspond to the value of a primary key in another table. ... ', 'all non-key attributes in a table must describe a characteristic of the object identified by the primary key.']
437318
['NOT NULL - Ensures that a column cannot have a NULL value.', 'UNIQUE - Ensures that all values in a column are different.', 'PRIMARY KEY - A combination of a NOT NULL and UNIQUE. ... ', 'FOREIGN KEY - Uniquely identifies a row/record in another table.']
1124592
The PRIMARY KEY constraint uniquely identifies each record in a table. Primary keys must contain UNIQUE values, and cannot contain NULL values. A table can have only ONE primary key; and in the table, this primary key can consist of single or multiple columns (fields).
849359
Primary keys - Contain one or more columns whose combined values uniquely identify every row in a table. Each table can have only one primary key. Alternate keys - Contain one or more columns whose combined values uniquely identify every row in a table.
650273
Difference between Primary Key and Candidate key. ... Primary Key is a unique and non-null key which identify a record uniquely in table. A table can have only one primary key. Candidate key is also a unique key to identify a record uniquely in a table but a table can have multiple candidate keys.
426896
['Self-describing nature of a database system.', 'Insulation between programs and data, and data abstraction.', 'Support of multiple views of the data.', 'Sharing of data and multiuser transaction processing.']
603511
2NF and 3NF are all about being dependent on the primary key. Recall that a primary key can be made up of multiple columns. As Chris said in his response: The data depends on the key [1NF], the whole key [2NF] and nothing but the key [3NF] (so help me Codd).
937099
['Factor 1: Key Storage. ... ', 'Factor 2: Key rotation and destruction. ... ', 'Factor 3: Key generation granularity. ... ', 'Factor 4: Automation. ... ', 'Factor 5: Easy to use interface. ... ', 'The SEC of KMS evaluation.']
784634
A primary key is a table column that serves a special purpose. Each database table needs a primary key because it ensures row-level accessibility. ... The values that compose a primary key column are unique; no two values are the same. Each table has one and only one primary key, which can consist of one or many columns.
650466
['(1) Permanence:', '(2) Exclusiveness:', '(3) All Comprehensiveness:', '(4) Inalienability:', '(5) Unity:', '(6) Imperscriptibility:', '(7) Indivisibility:', '(8) Absoluteness:']
581663
The primary key is a unique key in your table that you choose that best uniquely identifies a record in the table. All tables should have a primary key, because if you ever need to update or delete a record you need to know how to uniquely identify it. A surrogate key is an artificially generated key.
357493
Introduction to MySQL primary key A primary key is a column or a set of columns that uniquely identifies each row in the table. ... If the primary key consists of multiple columns, the combination of values in these columns must be unique. A primary key column cannot have NULL values.
105977
['Density.', 'Viscosity.', 'Temperature.', 'Pressure.', 'Specific Volume.', 'Specific Weight.', 'Specific Gravity.']
395942
Primary key is used to identify data uniquely therefore two rows can't have the same primary key. It can't be null. On the other hand, foreign key is used to maintain relationship between two tables. Primary of a table act as forgein key in the other table.
271307
['Single repository of data is maintained.', 'All users access the data from the same resource.', 'Quick retrieval of data.', 'Reduce application development time.', 'Flexibility in change of database structure.', 'Enforce standardization.', 'Up-to-date information availability.', 'Authorized access security of data.']
1138582
There are three general characteristics of Data Sets namely: Dimensionality, Sparsity, and Resolution. We shall discuss what do they exactly mean one at a time.