Identify the primary key column of Train and Reservation. -Technology

Identify the primary key column of Train and Reservation. -Technology
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1 Answer

Answer :

(i) Train-TrainIdReservation-RefNo(ii) (d) By default, the UNION operator selects all the values.
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Related questions

Primary key is used to …………….. identify the record. -Technology

Description : Primary key is used to …………….. identify the record. -Technology

Last Answer : Primary key is used to uniquelyidentify the record.

Why do we use reservation system? -Technology

Description : Why do we use reservation system? -Technology

Last Answer : It is a computerised system used to store and retrieve information and conduct transactions related to air travel, hotels, car rental or other activities.It is an application software which is commonly seen ... the seats or berths of any train and on any particular date with an incomparable speed.

Internet can bemused to get reservation of trains and air planes through ……….. service. -Technology

Description : Internet can bemused to get reservation of trains and air planes through ……….. service. -Technology

Last Answer : Internet can bemuse to get the reservation of trains and airplanes through E-reservation service.

Under which situation does reservation of a particular library resource takes place? -Technology

Description : Under which situation does reservation of a particular library resource takes place? -Technology

Last Answer : Reservation of particular library resources takes place only if the documents are not available for borrowing as they are issued to another member or sent for binding or otherwise unavailable.

What is a primary key? -Technology

Description : What is a primary key? -Technology

Last Answer : A field which uniquely identifies each record in a table is known as the primary key. e.g. emp id is the primary key of the Employee table.

Define primary key with an example. -Technology

Description : Define primary key with an example. -Technology

Last Answer : A field which uniquely identifies each record in a table is known as the primary key. e.g. emp id is the primary key of the Employee table.

What is primary key? Give an example. -Technology

Description : What is primary key? Give an example. -Technology

Last Answer : A field which uniquely identifies each record in a table is known as the primary key. e.g. emp id is the primary key of the Employee table.

What is a primary key in database? Give an example. -Technology

Description : What is a primary key in database? Give an example. -Technology

Last Answer : A field which uniquely identifies each record in a table is known as the primary key. e.g. emp id is the primary key of the Employee table.

Give one advantage of using primary key. -Technology

Description : Give one advantage of using primary key. -Technology

Last Answer : A primary key uniquely identifies the record in the table.

What is the significance of a primary key? -Technology

Description : What is the significance of a primary key? -Technology

Last Answer : A primary key cannot allow null values and must have a unique index.

What is the utility of primary key in database? Write distinct features of primary keys. -Technology

Description : What is the utility of primary key in database? Write distinct features of primary keys. -Technology

Last Answer : The primary key is used to uniquely identify the record in a database. It can be a column or a set of columns in the table.Main features of the primary key are as follows:1. It must contain a unique value for each record of the table.2. It does not contain null values.

Which of the following fields will not make a suitable primary key? (a) A customer’s account number -Technology

Description : Which of the following fields will not make a suitable primary key? (a) A customer’s account number -Technology

Last Answer : (b) From the given options, the data field can not be set as a primary key because it can’t be fixed for an object.

The candidate key, which is not used as primary key is called ………….. key. -Technology

Description : The candidate key, which is not used as primary key is called ………….. key. -Technology

Last Answer : The candidate key, which is not used as primary key is calledalternate key.

Primary key field gives us permission to record duplicate entry. -Technology

Description : Primary key field gives us permission to record duplicate entry. -Technology

Last Answer : False A primary key is a key which identifies records uniquely in a table so it does not give us permission to record duplicate entry.

A primary key field does not allow numbers. -Technology

Description : A primary key field does not allow numbers. -Technology

Last Answer : False Primary key has to identify a unique value which can be present in a table, in a number form also. It means primary key field allow number too.

A primary key value can be NULL. -Technology

Description : A primary key value can be NULL. -Technology

Last Answer : False The primary key of table is used to uniquely identify each and every row in the table. So, its all keys and columns must be defined as NOT NULL.

A foreign key is a primary key in another table. -Technology

Description : A foreign key is a primary key in another table. -Technology

Last Answer : True When a table’s primary key field is added to a related table in order to create the common field which relates two tables, it is called a foreign key in the related table.

What is a primary key? How do we set a primary key? -Technology

Description : What is a primary key? How do we set a primary key? -Technology

Last Answer : Primary key is the key which is used to uniquely identify the records into the table. To set the primary key you have to follow the steps given below:Step 1 Select the field that you want ... 2 Click Primary Key button from the Design tab.orRight click on the selected field and select Primary Key.

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What is a primary key in a table? -Technology

Description : What is a primary key in a table? -Technology

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Write any one similarity and one difference between primary key and unique Constraint. -Technology

Description : Write any one similarity and one difference between primary key and unique Constraint. -Technology

Last Answer : Similarity: Column with both the constraints will only take unique values.Difference: Column with Primary key constraints will not be able to hold NULL values while Column with Unique constraints will be able to hold NULL values.

Write any one similarity and one difference between primary key and unique Constraint -Technology

Description : Write any one similarity and one difference between primary key and unique Constraint -Technology

Last Answer : Similarity: Column with both the constraints will only take unique values.Difference: Column with Primary key constraints will not be able to hold NULL values while Column with Unique constraints will be able to hold NULL values.

In a relational database model, NULL values can be used for all but which one of the following? (A) To allow duplicate tuples in the table by filling the primary key column(s) with NULL. (B) To avoid confusion with actual legitimate data values like 0 (zero) for integer columns and ‘’ (the empty string) for string columns. (C) To leave columns in a tuple marked as “unknown” when the actual value is unknown. (D) To fill a column in a tuple when that column does not really “exist” for that particular tuple.

Description : In a relational database model, NULL values can be used for all but which one of the following? (A) To allow duplicate tuples in the table by filling the primary key column(s) with NULL. (B) To ... D) To fill a column in a tuple when that column does not really exist for that particular tuple.

Last Answer : (A) To allow duplicate tuples in the table by filling the primary key column(s) with NULL.

In the _______ method, the primary device controls the link; thesecondary devices follow its instructions. A) reservation B) polling C) token passing D) none of the above

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