Null (SQL)
Imagine you have a toy box with different kinds of toys, and you want to sort them out. When you find a toy car, you put it in the "car" category. When you find a toy boat, you put it in the "boat" category. But what if you find a toy that doesn't belong in any category? That's where the null value comes in.
In a similar way, databases use null to represent information that is missing or unknown. It's like a placeholder for when there's no value to put in a particular field. Maybe you forgot to fill in a field on a form, or maybe the data just wasn't available yet.
So, in SQL, "null" means there's no value in that specific field. It's different from an empty string or zero, which actually have a value (an empty string is still a string, and zero is still a number). Null means there's nothing there at all.
In a similar way, databases use null to represent information that is missing or unknown. It's like a placeholder for when there's no value to put in a particular field. Maybe you forgot to fill in a field on a form, or maybe the data just wasn't available yet.
So, in SQL, "null" means there's no value in that specific field. It's different from an empty string or zero, which actually have a value (an empty string is still a string, and zero is still a number). Null means there's nothing there at all.