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SQL Interview Preparation

Answer: Update a Value

Explore how to perform updates on SQL table records using the UPDATE statement with selective filtering using WHERE clauses. Understand different techniques including subqueries, joins, and session variables to modify data efficiently. Gain confidence in handling interview questions focused on updating values in SQL.

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Solution

The solution is given below:

MySQL
/* The UPDATE statement to update a record */
UPDATE Employees
SET    Salary = 55000
WHERE  EmpName = 'Sarah Ronald';
/* Retrieve the records from the Employees table where EmpID is 4 */
SELECT * FROM Employees
WHERE  EmpID = 4;

Explanation

The explanation of the solution code is given below:

  • Line 2: The UPDATE statement begins with the UPDATE keyword followed by a table name that will be modified.

  • Line 3: The SET clause specifies the column(s) and new values.

  • Line 4: The WHERE clause filters the record(s) in the table to determine which record we want to update based on the specified condition.

  • Line 7: The SELECT statement can be used to retrieve the records to verify the working of our update statement.

  • Line 8: The WHERE clause filters the record(s) with respect to ...