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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.
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Is it possible for the computer to generate values that are used as the primary key column?
Yes. Often times, an automatically generated key column will be a normal primary key using the auto_increment attribute.
What is a key field in database?
i key field is a field with with a key in the middle :)
Explain about primary key super key candidate key alternate key composite key foreign key?
KEYS IN SQL* 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.For Eg:The table:Emloyee(Name,Address,Ssn,Employee_Idprimary_key,Phone_ext)In the above example Ssn no. and employee identity are ccandidate keys.* 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.For Eg:Emloyee(Name,Address,Ssn,Employee_Idprimary_key,Phone_ext)* 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.For Eg:Emloyee(Name,Address,Ssn,Employee_Idprimary_key,Phone_ext)All the above are super keys.* 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.For Eg:For a Student....School(Name,Address,Phone,School_Reg_noprimary_key
Entity integrity constraint?
The entity integrity constraint states that no primary key value can be null. This is because the primary key value is used to identify individual tuples in a relation. Having null value for the primary key implies that we cannot identify some tuples. This also specifies that there may not be any duplicate entries in primary key column key row.
What is the super key in database management system?
the super key is the windows key (the flag) in non-windows OS
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.
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.
What is the difference between a Primary Key and a Secondary Key?
A Primary Key is a unique identifier for each record in a database table and is used to enforce entity integrity. A Secondary Key is a non-unique index that is used for querying and organizing data efficiently but does not have the constraint of uniqueness.
In a data base the primary key field is used to?
uniquely identify a record
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.
What is the meaning of primary key in Microsoft access?
The primary key is the designation given to the field or fields that make a record unique in a table. Often times in Access an autonumber field is used as the primary key because Access will always generate a unique number for each record. Having a primary key is not a requirement but it is highly recommended that you have a primary key in each table.
Is the last name a primary key?
In some cases, a last name can be used as a primary key if it uniquely identifies each record in a dataset. However, it is generally not recommended to use a last name as a primary key due to the potential for duplication or changes over time. It is often better to use a combination of attributes to create a more robust primary key.
What is candidate key in dbms?
more than one primary key to identify the record uniquely is called candidate key.
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 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.
Can the FirstName column be a primary key?
Yes, the FirstName column can be a primary key as long as it satisfies the requirements of a primary key, which include being unique and not null. However, it is generally not recommended to use a person's first name as a primary key as it may not be unique and could lead to data integrity issues.
