What is Auto Increment?

What is Auto Increment?

• A. Automatically increments a column value for each new row
• B. A function that resets counts
• C. A trigger for updates
• D. A type of constraint

Answer: (A)

Auto increment means the database automatically assigns a unique, increasing value to a designated column for every new row inserted into a table. This is especially handy for primary keys, because you usually want a unique identifier for each record without having to supply it yourself. When you add a new row and omit that column, the database fills in the next number in the sequence (like 1, 2, 3, …). Different systems implement this in slightly different ways—MySQL uses an AUTO_INCREMENT attribute on the column, PostgreSQL uses SERIAL or IDENTITY (which creates an underlying sequence), and SQL Server uses IDENTITY. It isn’t a function you call, nor a trigger that runs on updates, and it isn’t a standalone constraint. It’s a property of the column that ensures every new row gets a new, unique value automatically.

Auto increment means the database automatically assigns a unique, increasing value to a designated column for every new row inserted into a table. This is especially handy for primary keys, because you usually want a unique identifier for each record without having to supply it yourself. When you add a new row and omit that column, the database fills in the next number in the sequence (like 1, 2, 3, …). Different systems implement this in slightly different ways—MySQL uses an AUTO_INCREMENT attribute on the column, PostgreSQL uses SERIAL or IDENTITY (which creates an underlying sequence), and SQL Server uses IDENTITY. It isn’t a function you call, nor a trigger that runs on updates, and it isn’t a standalone constraint. It’s a property of the column that ensures every new row gets a new, unique value automatically.