The NOT NULL constraint is a column constraint that ensures values stored in a column are not NULL . A column may contain only one NOT NULL constraint…

Secrets of programming

What does dot dot mean in SQL? Dot notation (sometimes called the membership operator) allows you to qualify an SQL identifier with another SQL identifier of which it…

Secrets of programming

The AVG() function returns the average value of an expression. Note: NULL values are ignored. What does Avg do in SQL? AVG () computes the average of a…

Secrets of programming