Transaction: A transaction is a logical unit of work. A sequence of process that must be completely completed or aborted. Intermediate states are not acceptable in the process of transaction. To make a transaction use a keyword “BEGIN TRANSACTION;”, insert SQL queries and commit the transaction. Syntax for “TRANSACTION”: BEGIN {TRANSACTION|TRAN}; SQL queries; COMMIT; “insert” query: The INSERT command in SQL is employed to add records to an existing table. INSERT will increase the number of rows in a table. Syntax for INSERT command: INSERT INTO table_name VALUES (value1, value2…); Example: INSERT INTO employee VALUES(101, ‘Smith’,10); “update” query: The UPDATE command is employed to update information present in a table. It is always used with SET keyword either in bulk or individually. UPDATE will not increase the number of rows in a table. Syntax for UPDATE command: UPDATE table_name SET column_name1 = value WHERE some_condition; Example: UPDATE employee SET name= ‘Presil’ age= 24 WHERE id=115;

Question

Consider the following table in a relational database.Last Name Rank Room ShiftSmith Manager 234 MorningJones Custodian 33 AfternoonSmith Custodian 33 EveningDoe Clerical 222 MorningAccording to the data shown in the table, which of the following could be candidate keys of the table?a) {Last Name}b) {Room}c) {Shift}d) {Rank, Room}e) {Room, Shift}

Answer 1

Question

Chapter 10, Problem 6P

a)

Program Plan Intro

Transaction:

A transaction is a logical unit of work.

A sequence of process that must be completely completed or aborted.

Intermediate states are not acceptable in the process of transaction.

To make a transaction use a keyword “BEGIN TRANSACTION;”, insert SQL queries and commit the transaction.

Syntax for “TRANSACTION”:

BEGIN {TRANSACTION|TRAN};

SQL queries;

COMMIT;

“insert” query:

The INSERT command in SQL is employed to add records to an existing table. INSERT will increase the number of rows in a table.

Syntax for INSERT command:

INSERT INTO table_name VALUES (value1, value2…);

Example:

INSERT INTO employee VALUES(101, ‘Smith’,10);

“update” query:

The UPDATE command is employed to update information present in a table.

It is always used with SET keyword either in bulk or individually. UPDATE will not increase the number of rows in a table.

Syntax for UPDATE command:

UPDATE table_name SET column_name1 = value WHERE some_condition;

Example:

UPDATE employee SET name= ‘Presil’ age= 24 WHERE id=115;

b)

Explanation of Solution

Program plan:

The following SQL query is to make a customer payment for a customer “10010” of “$100” in cash using the payment ID “3428”.

Begin the transaction.

Insert the appropriate values into “payments” table using “insert” query.

Update the customer details to reduce the customer balance by “100” for the customer “10010” using “update” query...

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