The Art of PostgreSQL/

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Solution Review: Understanding Nulls

Solution Review: Understanding Nulls

See a detailed analysis of the solution to the "Understanding Nulls" challenge.

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Task 1

You were asked to write a query to list the output using the SQL operator is null for the values true, false, and null.

Solution

The solution for the challenge is given below. Click the “Run” button in the following widget to see the output of the code.

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/***************************************************/
/*****     Write a query to list the output    *****/
/*****   using the SQL operator "is null" for  *****/
/*****       values true, false, and null.     *****/
/***************************************************/
select a::text as val_a,
       (a is null)::text as "is null"
  from (values(true),(false),(null)) t1(a);
/***************************************************/

Explanation

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