Q71. Insert a new record into Customers?
To insert a new record into the `Customers` table, specify the column names followed by the `VALUES` clause: ```sql INSERT INTO Customers (id, first_name, last_name, emai...
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Q72. Insert "Hawkins" as LastName in Customers?
To insert a row populating only the `LastName` column: ```sql INSERT INTO Customers (LastName) VALUES ('Hawkins'); ``` *Prerequisite:* This statement succeeds only if all...
Q73. How to create a temporary table in MySQL?
```sql CREATE TEMPORARY TABLE temp_top_customers SELECT * FROM customers WHERE total_spent > 10000; ``` It exists only for the current session/connection and is automatic...
Q74. Which statement updates data?
The **`UPDATE`** statement modifies existing data values in one or more rows of a table: ```sql UPDATE Customers SET email = 'new.email@example.com', updated_at = NOW() W...
Q75. Keyword in UPDATE to change values?
The keyword used in an `UPDATE` statement to specify new values for columns is **`SET`**: ```sql UPDATE employees SET salary = salary * 1.10, title = 'Senior Software Eng...
Q76. Change "Jackson" to "Hawkins" in LastName?
To update all customers with the last name "Jackson" to "Hawkins": ```sql UPDATE Customers SET LastName = 'Hawkins' WHERE LastName = 'Jackson'; ``` ### Production Best Pr...
Q77. Which statement deletes data?
The **`DELETE`** statement removes existing rows from a table based on a condition: ```sql DELETE FROM Customers WHERE is_active = 0 AND last_login < '2023-01-01'; ``` ##...
Q78. Delete records where FirstName is "John"?
To delete all rows where `FirstName` equals "John": ```sql DELETE FROM Customers WHERE FirstName = 'John'; ``` *Safety Warning:* If you accidentally omit `WHERE FirstName...
Q79. What is FROM used for?
The **`FROM`** clause defines the source table(s), views, joined datasets, or subqueries from which rows are read: ```sql SELECT u.username, p.title FROM users u INNER JO...
Q80. DELETE vs TRUNCATE?
See the comparison table above. Key differences: `DELETE` is DML (row-by-row, rollbackable, fires triggers, has WHERE). `TRUNCATE` is DDL (bulk page deallocation, faster,...