Simple SQL Quiz

ACID stands for Atomicity (all or nothing), Consistency (valid state transitions), Isolation (concurrent transactions don't interfere), and Durability (committed changes persist). These are the fundamental properties of database transactions.

The ORDER BY clause in SQL is used to sort query results in ascending or descending order. ORDER FROM, ORDER ON, and ORDER IN are not valid SQL syntax for controlling sort order.

DISTINCT is the correct SQL keyword to eliminate duplicate rows from query results. It's used in the SELECT clause like 'SELECT DISTINCT column_name'. UNIQUE is a constraint for table definition, not a query clause.

SQRT() is a scalar function that returns a single value (square root). COUNT() and AVG() are aggregate functions that work on multiple rows and return a single aggregated value. The question asks for a single-value (scalar) function.

/**/ is the C-style block comment syntax used in SQL for multiline comments, while REM is typically a single-line comment in some SQL dialects. *** is not a valid comment syntax, and <%--%> is used in JSP/ASP for server-side comments, not SQL.