This question evaluates the candidate's familiarity with performing operations on a table using PostgreSQL. It requires understanding of SQL queries and specifically, using SELECT statements with DISTINCT and ORDER BY clauses. The candidate must be able to understand the requirements of the query and choose the appropriate combination of clauses to achieve the desired result.

This question evaluates the candidate's knowledge of Linux command-line usage and specifically, how to check the status of a service. It requires understanding of the 'service' command and the correct syntax to check the status of the PostgreSQL service on a Linux (Ubuntu) machine.

This question evaluates the candidate's understanding of efficient data insertion techniques in PostgreSQL. It requires knowledge of different commands available for inserting data in bulk, such as the COPY command and the INSERT command. The candidate must also be aware of the differences between these commands and the UPDATE command.

This question evaluates the candidate's understanding of how a specific SQL query is evaluated in PostgreSQL. It requires knowledge of the UNION operator and the concept of query evaluation order.

This question evaluates the candidate's understanding of PostgreSQL data type conversion using the ALTER TABLE command. It requires knowledge of implicit casts, default values, and constraints in PostgreSQL. The candidate must determine which choices are true regarding the conversion process.

This question evaluates the candidate's understanding of SQL and database operations. It tests their knowledge of query execution with cursor variables, dynamic queries, query parameters, and string formatting. The candidate needs to analyze the given statement to determine the correct inference about the table name and comparison value insertion method.

This question evaluates the candidate's knowledge of PostgreSQL's transaction management and the behavior of database operations when autocommit is turned off. It tests whether the candidate understands the concept of a transaction, rollback, and the effect of a failed insertion on previous insertions.

This question evaluates the candidate's understanding of how PostgreSQL establishes relationships between rows in separate tables.

This question assesses the candidate's knowledge of SQL and the UPDATE command. It tests the understanding of the required information when updating existing rows in a table.

This question evaluates the candidate's understanding of SQL aggregate functions and the ORDER BY clause. It requires knowledge of how to correctly structure queries to achieve a specific objective. The candidate must identify the incorrect implementation among two provided queries.

This question assesses the candidate's skill in SQL querying, specifically in retrieving data based on specified conditions, joining tables, and identifying the maximum value within a group.