Approximately 2.81 × 1 0 21 electrons flow through an electric device that delivers a current of 15.0 A for 30 seconds. This is calculated by first determining the total charge that flows and then dividing that by the charge of a single electron. The relationship between current, charge, and time is crucial for this calculation.
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Let's address each part of the question related to managing a database in SQL, focusing on the table 'STORE' within the database 'mystore'.
(a) Identify the attribute best suitable to be declared as a primary key. The primary key in a database is a unique identifier for each row in a table. In this case, 'ItemNo' seems to be the most suitable attribute to be declared as the primary key, because it is numeric and unique to each item in the table, ensuring that each row can be uniquely identified by this attribute.
(b) Write the query to add the row with the following details (2010, 'Notebook', 23, 155). To insert a new row in the table, you would use the INSERT INTO SQL command like so:
INSERT INTO STORE (ItemNo, ItemName, Scode, Quantity) VALUES (2010, 'Notebook', 23, 155);
(c)(i) Abhay wants to remove the table 'STORE' from the database 'mystore'. To remove the table 'STORE', the SQL command DROP TABLE is used:
DROP TABLE STORE;
(ii) Display the structure of the table 'STORE'. To display the structure of the table, which includes the attributes and their data types, you can use the DESCRIBE command:
DESCRIBE STORE;
OR
(i) Abhay wants to ADD a new column 'price' with data type as decimal. To add a new column to an existing table, you can use the ALTER TABLE command:
ALTER TABLE STORE ADD COLUMN price DECIMAL(10, 2);
(ii) Abhay wants to remove a column 'price' from the table 'STORE'. To remove a column, you can again use the ALTER TABLE command:
ALTER TABLE STORE DROP COLUMN price;
By using these SQL queries and commands, Abhay can effectively manage the 'STORE' table within the 'mystore' database, ensuring that the inventory is maintained accurately and efficiently.