Creating named functions and declaring variables

Now that you've seen a powerful debugging function in action, let's build one of your own. First, start by using defining the function signature which supplied the function name, any parameters, and a return type. After that point, it's the same as a DO function.

This exercise is part of the course

Transactions and Error Handling in PostgreSQL

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Exercise instructions

Define a function named debug_statement that takes a SQL statement as sql_stmt.
The return type of the function should be a BOOLEAN.
The function should execute the supplied SQL statement and catch any exception.
The function should return True if it triggers debugging and False if it does not.

Hands-on interactive exercise

Have a go at this exercise by completing this sample code.

-- Define our function signature
___ ___ ___ ___ debug_statement(
    sql_stmt TEXT
)
-- Declare our return type
___ ___ AS $$
    DECLARE
        exc_state   TEXT;
        exc_msg     TEXT;
        exc_detail  TEXT;
        exc_context TEXT;
    BEGIN
        BEGIN
            -- Execute the statement passed in
            ___ sql_stmt;
        EXCEPTION WHEN others THEN
            GET STACKED DIAGNOSTICS
                exc_state   = RETURNED_SQLSTATE,
                exc_msg     = MESSAGE_TEXT,
                exc_detail  = PG_EXCEPTION_DETAIL,
                exc_context = PG_EXCEPTION_CONTEXT;
            INSERT into errors (msg, state, detail, context) values (exc_msg, exc_state, exc_detail, exc_context);
            -- Return True to indicate the statement was debugged
            ___ ___;
        END;
        -- Return False to indicate the statement was not debugged
        RETURN ___;
    END;
$$ LANGUAGE plpgsql;
SELECT debug_statement('INSERT INTO patients (a1c, glucose, fasting) values (20, 89, TRUE);')

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