Wednesday, February 19, 2020

Aggregate functions COUNT

  1. SELECT COUNT(*) FROM books;
  2.  
  3. SELECT COUNT(author_fname) FROM books;
  4.  
  5. SELECT COUNT(DISTINCT author_fname) FROM books;
  6.  
  7. SELECT COUNT(DISTINCT author_lname) FROM books;
  8.  
  9. SELECT COUNT(DISTINCT author_lname, author_fname) FROM books;
  10.  
  11. SELECT title FROM books WHERE title LIKE '%the%';
  12.  
  13. SELECT COUNT(*) FROM books WHERE title LIKE '%the%';
at

No comments:

Post a Comment

Subscribe to: Post Comments (Atom)

Right Joins

-- OUR FIRST RIGHT JOIN (seems the same as a left join?) SELECT * FROM customers RIGHT JOIN orders     ON customers.id = orders.custom...

  • TimeStamps
    CREATE TABLE comments ( content VARCHAR ( 100 ), created_at TIMESTAMP DEFAULT NOW () );   INSERT INTO comments ( content ) V...
  • Setting Default Values
    CODE: Setting Default Values  Define a table with a DEFAULT name specified: CREATE TABLE cats3 ( name VARCHAR ( 20 ) DEFAUL...
  • CONCAT()
    SELECT author_fname , author_lname FROM books ;   CONCAT ( x , y , z ) // from slides   CONCAT ( column , anotherColumn ) // from ...