Why or condition is working differently compare with Java and SQL

Question

In Java,

int a = 10, b = 10;

if (a == 10 || b==10)
{
// first condition (a==10) is true, so it wont check further
}

But, in SQL,

select * from my table where a = 10 or b = 10;

--As per my understanding, It should return data only based on a.
--But it returns both entries. 

Why is that?

Answer 1

You are describing early termination - this means the second statement is only executed if the answer isn't already known, but it doesn't change the outcome (unless you execute an expression in the second statement).

So a == 10 || b == 10 will result in anything where a, or b is 10 - or where a and b are 10. Or more precisely...

a = 10
b = 10

Or

a = 10
b = 0

Or

a = 0
b = 10

If a happens to be 10, you don't really need to check b - but some languages still do.

Answer 2

This is not a great comparison to make. However, it's not necessarily working any different. If you were to add

if (a == 10 || b==10)
{
// first condition (a==10) is true, so it wont check further
// return a or b
}

It would return every time where a or b is 10. Pretty much the same logic behind the SQL statement.

The problem is with how you're misinterpreting WHERE, this will in fact return every record where a or b is 10.

Answer 3

The difference is that in Java we are checking for a conditional logic and not aggregation like SQL is doing.

Java does short-circuiting meaning that if the first operand checked is true, it will not do the other operands.

In SQL the WHERE statements is looking for all a conditions and b conditions independently since you are using or