Understanding SQL UPDATE Command to Modify Database Records

SQL (Structured Query Language) is a standard language for managing and manipulating databases. One aspect of managing databases is updating existing data. In SQL, UPDATE is the command that allows us to modify existing records in a database. The question pertains to the usage of this command to update employee salary details in an 'Employees' table.

The correct syntax as given in the question is: UPDATE Employees SET Salary = 50000 WHERE EmployeeID = 123.

Let's break it down:

• UPDATE command is used to modify the existing records in a table.

• Employees is the name of the table we are updating.

• SET keyword is used to specify the new value for the column we are updating – in this case, we're changing the 'Salary' column.

• We then specify the new value for the salary, 50000.

• The WHERE clause is extremely important – it specifies exactly which record or records should be updated. In this case, we're changing the salary for the employee with 'EmployeeID' 123. Without it, the UPDATE command would change the salary for all employees in the table.

So, the entire command UPDATE Employees SET Salary = 50000 WHERE EmployeeID = 123 is telling the database to change the salary of the employee with the ID 123 to 50000.

It's important to note that incorrect commands depicted in the other options like 'CHANGE', 'MODIFY' and 'EDIT', are not valid SQL commands for updating records.

Best Practices for Using UPDATE Command

• Always use WHERE clause: You should always ensure you use a WHERE clause with your UPDATE command. Without it, the command will update all the records in the table, which is often not what you want.

• Consider Transactions: For multiple UPDATE statements, using database transactions is advisable. This way, if something goes wrong with one statement, you can roll back all changes.

• Backup Data: Before executing an UPDATE statement on a production database, do a backup. Alternatively, before the UPDATE statement, use the SELECT statement to check the affected rows.

In conclusion, understanding SQL commands and their correct usage is essential to efficiently manage and manipulate data stored in databases.