Why JSON support matters in PostgreSQL - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to select the JSON data from the column named 'data'.

PostgreSQL

SELECT [1] FROM my_table;

Drag options to blanks, or click blank then click option'

A'data'

Bjson

Cjson_data

Ddata

Attempts:

3 left

💡 Hint

Common Mistakes

Using quotes around the column name, which makes it a string literal.

Using a wrong column name.

To select a column in SQL, just use its name without quotes.

2fill in blank

medium

Complete the code to extract the value of the key 'name' from the JSON column 'data'.

PostgreSQL

SELECT data[1]'name' FROM my_table;

Drag options to blanks, or click blank then click option'

A#>>

B->>

C->

D#>

Attempts:

3 left

💡 Hint

Common Mistakes

Using -> which returns JSON instead of text.

Using the wrong operator for key extraction.

The operator ->> extracts the JSON object field as text.

3fill in blank

hard

Fix the error in the query to filter rows where the JSON key 'age' is greater than 30.

PostgreSQL

SELECT * FROM my_table WHERE (data->>[1])::int > 30;

Drag options to blanks, or click blank then click option'

A'age'

Bage

C"age"

Ddata

Attempts:

3 left

💡 Hint

Common Mistakes

Not quoting the key name, causing syntax errors.

Using double quotes instead of single quotes.

JSON keys must be in single quotes inside the operator.

4fill in blank

hard

Fill both blanks to create a JSON object with keys 'name' and 'age' from columns.

PostgreSQL

SELECT json_build_object([1], name, [2], age) FROM my_table;

Drag options to blanks, or click blank then click option'

A'name'

B'age'

Cname

Dage

Attempts:

3 left

💡 Hint

Common Mistakes

Using column names as keys without quotes.

Mixing up keys and values.

Keys in JSON objects must be strings in quotes.

5fill in blank

hard

Fill all three blanks to filter rows where the JSON key 'status' equals 'active'.

PostgreSQL

SELECT * FROM my_table WHERE data[1]'status' [2] [3];

Drag options to blanks, or click blank then click option'

A->>

B=

C'active'

D->

Attempts:

3 left

💡 Hint

Common Mistakes

Using -> which returns JSON, not text.

Not quoting the string 'active'.

Using wrong comparison operators.

Use ->> to extract text, then compare with '=' to the string 'active'.