Question

Which PostgreSQL \pset command is used to make NULL values visible in the query output?

Option 1:
sql
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\Pset null_display 'NULL';
Option 2:
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\Pset null_as_visible ON;
Option 3:
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\Pset null 'visible';
Option 4:
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\Pset null_display 'visible';

Answer 1

The correct command to make NULL values visible in PostgreSQL query output is \Pset null 'NULL';, which is Option 1. It sets the display string for NULL values in the psql terminal, providing clarity in query results.

The correct PostgreSQL \pset command to make NULL values visible in the query output is Option 1: \Pset null 'NULL';. This command configures the psql interactive terminal to display the word 'NULL' when it encounters a NULL value in the query output, making it easier to distinguish NULL values from empty strings or other data.

Options 2, 3, and 4 are incorrect and are not recognized commands in PostgreSQL. The proper syntax revolves around the null setting in the \pset command, which takes a string that defines how NULL values should be represented in the output. In practice, you might use different strings based on your preferences or requirements, but it's important to use the correct syntax to achieve the desired effect.

So, using \Pset null 'NULL'; is an effective way to highlight NULL values in your query results, allowing for clearer understanding and analysis of the data returned by your SQL queries.