Why Does My PostgreSQL Query Fail with 'Column \'Continent\' Does Not Exist' Despite the Column Existing?

PostgreSQL database error: Column 'Continent' does not exist

Problem background:

A Java application encountered an error when querying the database that the column "Continent" did not exist in a specific table, despite confirming that the column existed in pgAdmin 4. The query attempts to select non-null values ​​from this column.

Problem Diagnosis:

• Verified via pgAdmin 4 that the column "Continent" does exist in the "network.countries" table.
• The query shows that the application obtains column and table names correctly, excluding spelling or semantic errors.
• The error message implies that the column names may need to be referenced using a different schema or table.

Solution:

Fix this issue by surrounding the column names in double quotes in the query:

SELECT "Continent"
FROM network.countries
...

PostgreSQL requires that column names must be enclosed in double quotes when they contain special characters or conflict with keywords. In this case, "Continent" is a reserved keyword in PostgreSQL, so it needs to be enclosed in quotes.

Additional notes:

• Running the query directly in pgAdmin 4 may not encounter the same error, as the interface handles quotes automatically.
• Using "countries.Continent" in the query may also work, but this introduces a dependency on the "countries" pattern. Wrapping the column names in double quotes provides a more general solution that works regardless of the schema the table is in.

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