PQresultStatus
Function
PQresultStatus is used to return the result status of a command.
Prototype
ExecStatusType PQresultStatus(const PGresult *res);Parameter
Table 1 PQresultStatus parameter
Return Value
PQresultStatus indicates the command execution status. The enumerated values are as follows:
PQresultStatus can return one of the following values:
PGRES_EMPTY_QUERY
The string sent to the server was empty.
PGRES_COMMAND_OK
A command that does not return data was successfully executed.
PGRES_TUPLES_OK
A query (such as SELECT or SHOW) that returns data was successfully executed.
PGRES_COPY_OUT
Copy Out (from the server) data transfer started.
PGRES_COPY_IN
Copy In (to the server) data transfer started.
PGRES_BAD_RESPONSE
The response from the server cannot be understood.
PGRES_NONFATAL_ERROR
A non-fatal error (notification or warning) occurred.
PGRES_FATAL_ERROR
A fatal error occurred.
PGRES_COPY_BOTH
Copy In/Out (to and from the server) data transfer started. This state occurs only in streaming replication.
PGRES_SINGLE_TUPLE
PGresult contains a result tuple from the current command. This state occurs in a single-row query.Precautions
Note that the SELECT command that happens to retrieve zero rows still returns PGRES_TUPLES_OK. PGRES_COMMAND_OK is used for commands that can never return rows (such as INSERT or UPDATE, without return clauses). The result status PGRES_EMPTY_QUERY might indicate a bug in the client software.
The result status PGRES_NONFATAL_ERROR will never be returned directly by PQexec or other query execution functions. Instead, such results will be passed to the notice processor.
Example
For details, see Example.