PL/SQL Interview — SQL Technical Interview Questions & Answers

PL/SQL Interview

PL/SQL Interview

  • A view is a saved SELECT with a name. CREATE VIEW fail_list AS SELECT name, marks FROM students WHERE marks < 40; Then SELECT * FROM fail_list; looks like a table but it runs that query each time (simple views).
  • Teachers like views for ‘show only what this role should see’. You don’t copy data. If students.marks changes, fail_list changes.
  • Some views are not updatable (JOIN, GROUP BY). INSERT into fail_list may fail. Don’t promise ‘views always write back’.
  • Trap: thinking a view stores a snapshot forever. Unless you made a table, it is a query with a nickname.
  • On the example next to this theory: Interview: create two demo rows, then SELECT qty >= 2 ordered. Say which labels come back.
  • On the example next to this theory: SQL Interview: create two demo rows, then SELECT qty >= 2 ordered. Say which labels come back.
  • On the example next to this theory: PL/SQL Interview: create two demo rows, then SELECT qty >= 2 ordered. Say which labels come back.

Technical Interview Tip: CREATE VIEW fail_list AS SELECT … WHERE marks < 40;

Code Examples for PL/SQL Interview

PL/SQL Interview — sample query

-- PL/SQL Interview
CREATE TABLE demo (
  id INTEGER PRIMARY KEY,
  label TEXT NOT NULL,
  qty INTEGER DEFAULT 0
);
INSERT INTO demo (id, label, qty) VALUES
  (1, 'alpha', 2),
  (2, 'beta', 5);
SELECT label, qty FROM demo WHERE qty >= 2 ORDER BY qty DESC;

PL/SQL Interview: create two demo rows, then SELECT qty >= 2 ordered. Say which labels come back.

How to Explain PL/SQL Interview to an Interviewer

What is a view?

A saved SELECT with a name Not a second copy of the data

Can you always UPDATE a view?

No JOINs / GROUP BY often block it