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What is the primary characteristic of a key field as that it must be?
Wiki User
∙ 6y ago
It must be at least regular as well as totally ordered. To be totally ordered, the key field must be of a type that provides all six comparison operations (<, <=, >, >=, == and !=). In some implementations, the less-than operator is all that is required for total order because all other comparison operations can be expressed in terms of this one operator alone:
a>b is the same as saying b<a
a>=b is the same as saying b<a AND NOT (a<b)
a<=b is the same as saying a<b AND NOT (b<a)
a==b is the same as saying NOT (a<b) AND NOT (b<a)
a!=b is the same as saying a<b OR b<a
Wiki User
∙ 6y ago
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Can you insert primary key only to one field in the database?
Yes. Primary key can be inserted to one field in the database. The field should be unique and not null.
What is another name for a primary key?
Also called a Key field.
what field is used as a primary key?
We explicitly choose a primary key.A primary key should satisfy the following conditions: 1) it should not be null 2) it should be unique.
True or false A foreign key is a field in one table that refers to the primary key field in another table and indicates how the the tables are related?
True.
All types of keys in database?
* Alternate key - An alternate key is any candidate key which is not selected to be the primary key * Candidate key - A candidate key is a field or combination of fields that can act as a primary key field for that table to uniquely identify each record in that table. * Compound key - compound key (also called a composite key or concatenated key) is a key that consists of 2 or more attributes. * Primary key - a primary key is a value that can be used to identify a unique row in a table. Attributes are associated with it. Examples of primary keys are Social Security numbers (associated to a specific person) or ISBNs (associated to a specific book). In the relational model of data, a primary key is a candidate key chosen as the main method of uniquely identifying a tuple in a relation. * Superkey - A superkey is defined in the relational model as a set of attributes of a relation variable (relvar) for which it holds that in all relations assigned to that variable there are no two distinct tuples (rows) that have the same values for the attributes in this set. Equivalently a superkey can also be defined as a set of attributes of a relvar upon which all attributes of the relvar are functionally dependent. * Foreign key - a foreign key (FK) is a field or group of fields in a database record that points to a key field or group of fields forming a key of another database record in some (usually different) table. Usually a foreign key in one table refers to the primary key (PK) of another table. This way references can be made to link information together and it is an essential part of database normalization
What is A field that uniquely identifies a particular record in a table called?
A field that uniquely identifies a particular record in a table is called a primary key. The field or fields on which records are sorted is called the sort key.
What not a likely primary key?
A field that is not unique and null can not be used as a primary key. Praimary key must satisfy the conditions of not null and unique.
Which field MS Access will not allow you to delete?
A primary key field.A primary key field.A primary key field.A primary key field.A primary key field.A primary key field.A primary key field.A primary key field.A primary key field.A primary key field.A primary key field.
Have all tables primary key?
No, all tables do not have primary key. Primary must be explicitly defined and must not be null.
Is it necessarily that a foreign key is primary key in other table?
It is not mandatory that is must be a primary key but it must be a unique key in the other table.
Can you insert primary key only to one field in the database?
Yes. Primary key can be inserted to one field in the database. The field should be unique and not null.
Differentiate between primary secondary and foreign keys?
Primary key uniquely identifies each record in a database table and must have a unique value for each record. Secondary key is a field that can be used to uniquely identify a record, but it is not the primary key. Foreign key is a field in a table that links to the primary key of another table, establishing a relationship between the two tables.
Can a primary key refer to a whole table?
No, a primary key do not refers to the whole table .A primary key refers to a field in the table that is not null and unique.
What type of field cannot hold duplicate value in ms access?
A primary key field is always unique. Any other field that you have can be set to not allow duplicate values if necessary too.A primary key field is always unique. Any other field that you have can be set to not allow duplicate values if necessary too.A primary key field is always unique. Any other field that you have can be set to not allow duplicate values if necessary too.A primary key field is always unique. Any other field that you have can be set to not allow duplicate values if necessary too.A primary key field is always unique. Any other field that you have can be set to not allow duplicate values if necessary too.A primary key field is always unique. Any other field that you have can be set to not allow duplicate values if necessary too.A primary key field is always unique. Any other field that you have can be set to not allow duplicate values if necessary too.A primary key field is always unique. Any other field that you have can be set to not allow duplicate values if necessary too.A primary key field is always unique. Any other field that you have can be set to not allow duplicate values if necessary too.A primary key field is always unique. Any other field that you have can be set to not allow duplicate values if necessary too.A primary key field is always unique. Any other field that you have can be set to not allow duplicate values if necessary too.
What is another name for a primary key?
Also called a Key field.
What symbol means the field is the primary key for the table appears in front of a field in the table window?
key
What are field can be used as primary key?
A field or set a of fields Êin a database tableÊwith unique values Êcan be used as a primary key.ÊPrimary key field cannot have a null value.
