After some discussions about what could be useful since psql scripts now accepts tests, this patch sets a few variables which can be used by psql after a "front door" (i.e. actually typed by the user) query:
- RESULT_STATUS: the status of the query - ERROR: whether the query failed - ERROR_MESSAGE: ... - ROW_COUNT: #rows affected
SELECT * FROM ; \if :ERROR \echo oops \q \endif
I'm not sure that the names are right. Maybe STATUS would be better than RESULT_STATUS.
I am sending review of this patch:
1. I agree so STATUS is better name, than RESULT status. Currently it returns values with prefix PGRES (like PGRES_FATAL_ERROR, PGRES_TUPLES_OK). Maybe we should to cut this prefix. FATAL_ERROR, TUPLES_OK looks better for custom level. The PGRES prefix has not sense in psql.
2. I propose availability to read ERROR_CODE - sometimes it can be more practical than parsing error possible translated message
3. The fields ERROR_MESSAGE and ROW_COUNT are set only when it has sense. This behave is maybe too strict for psql and the processing needs more nesting \if command. What do you think about -1 or 0 for ROW_COUNT (for DDL) and "" for ERROR_MESSAGE when there are not any error? It will be consistent with already implemented LASTOID variable (and other state psql variables). Using default values are not strict clean, but it can reduce complexity of psql scripts.