How to diagnose and fix the 2000 no_data error code in Postgres.

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The 2000 error code in PostgreSQL corresponds to a no_data condition, which is not an error but rather an indication that a query or operation returned no data when some data was expected. This can happen, for example, when you use a SELECT INTO statement and the query does not return any rows.

To handle this situation, you can use exception handling in PL/pgSQL, PostgreSQL’s procedural language. Here’s an example of how you might handle a no_data situation:

DO $$
DECLARE
    rec record;
BEGIN
    -- Attempt to select a record into 'rec'
    SELECT INTO rec * FROM my_table WHERE id = 1;

    -- If no data is found, raise a notice or handle accordingly
    IF NOT FOUND THEN
        RAISE NOTICE 'No data found with id = 1.';
        -- Additional handling code can go here
    END IF;

EXCEPTION
    WHEN NO_DATA_FOUND THEN
        -- Handle the no_data condition here if needed
        RAISE NOTICE 'No data found with id = 1 in EXCEPTION block.';
END $$;

In the above code, if the SELECT INTO does not populate rec because no row was found with id = 1, the IF NOT FOUND THEN block will be executed, and a notice will be raised. If you want to specifically catch the no_data condition in the exception block, you can use the WHEN NO_DATA_FOUND THEN block to handle it.

Handling a no_data condition is crucial in stored procedures or functions where you expect a result and need to ensure that the absence of data is managed correctly. For more detailed examples and explanations of exception handling in PostgreSQL, you can refer to the official PostgreSQL documentation on error codes and the PostgreSQL tutorial on exceptions.

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