[Solved] Given the following SQL commands, what will be the output of the last SELECT? CREATE EXTENSION IF NOT EXISTS hstore; SELECT 'a=>1, b=>2'::hstore -> 'a' AS value_a; | PostgreSQL

PostgreSQL - Advanced Features

Given the following SQL commands, what will be the output of the last SELECT?

CREATE EXTENSION IF NOT EXISTS hstore;
SELECT 'a=>1, b=>2'::hstore -> 'a' AS value_a;

ASyntax error

B1

CNULL

D'1'

Step-by-Step Solution

Solution:

Step 1: Understand hstore key-value retrieval
The operator -> when used with hstore returns the value as type hstore, which is text but includes quotes in output.
Step 2: Analyze the given hstore and query
The hstore contains keys 'a' and 'b' with values '1' and '2' as text. Selecting -> 'a' returns the value as text with quotes, so output is '1'.
Final Answer:
'1' -> Option D
Quick Check:
hstore -> key returns quoted text value [OK]

Quick Trick: hstore -> key returns text value shown quoted [OK]

Common Mistakes:

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Given the following SQL commands, what will be the output of the last SELECT?