Minor updates to libpq documentation.
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Tom Lane
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@ -430,6 +430,24 @@ PGRES_FATAL_ERROR
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</Para>
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</ListItem>
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<ListItem>
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<Para>
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<Function>PQresStatus</Function>
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Converts the enumerated type returned by PQresultStatus into
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a string constant describing the status code.
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<synopsis>
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const char *PQresStatus(ExecStatusType status);
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</synopsis>
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Older code may perform this same operation by direct access to a constant
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string array inside libpq,
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<synopsis>
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extern const char * const pgresStatus[];
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</synopsis>
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However, using the function is recommended instead, since it is more portable
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and will not fail on out-of-range values.
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</Para>
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</ListItem>
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<ListItem>
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<Para>
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<Function>PQresultErrorMessage</Function>
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@ -910,8 +928,7 @@ terms is readable data on the file descriptor identified by PQsocket.
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When the main loop detects input ready, it should call PQconsumeInput
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to read the input. It can then call PQisBusy, followed by PQgetResult
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if PQisBusy returns FALSE. It can also call PQnotifies to detect NOTIFY
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messages (see "Asynchronous Notification", below). An example is given
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in the sample programs section.
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messages (see "Asynchronous Notification", below).
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</Para>
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<Para>
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@ -1230,10 +1247,10 @@ int PQendcopy(PGconn *conn);
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As an example:
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<ProgramListing>
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PQexec(conn, "create table foo (a int4, b char16, d float8)");
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PQexec(conn, "create table foo (a int4, b char(16), d float8)");
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PQexec(conn, "copy foo from stdin");
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PQputline(conn, "3<TAB>hello world<TAB>4.5\n");
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PQputline(conn,"4<TAB>goodbye world<TAB>7.11\n");
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PQputline(conn, "3\thello world\t4.5\n");
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PQputline(conn,"4\tgoodbye world\t7.11\n");
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...
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PQputline(conn,"\\.\n");
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PQendcopy(conn);
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@ -1671,22 +1688,25 @@ main()
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<Para>
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<ProgramListing>
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/*
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* testlibpq2.c Test of the asynchronous notification interface
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* testlibpq2.c
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* Test of the asynchronous notification interface
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*
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* populate a database with the following:
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* Start this program, then from psql in another window do
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* NOTIFY TBL2;
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*
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* CREATE TABLE TBL1 (i int4);
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* Or, if you want to get fancy, try this:
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* Populate a database with the following:
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*
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* CREATE TABLE TBL2 (i int4);
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* CREATE TABLE TBL1 (i int4);
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*
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* CREATE RULE r1 AS ON INSERT TO TBL1 DO [INSERT INTO TBL2 values
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* (new.i); NOTIFY TBL2];
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* CREATE TABLE TBL2 (i int4);
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*
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* Then start up this program After the program has begun, do
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*
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* INSERT INTO TBL1 values (10);
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* CREATE RULE r1 AS ON INSERT TO TBL1 DO
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* (INSERT INTO TBL2 values (new.i); NOTIFY TBL2);
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*
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* and do
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*
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* INSERT INTO TBL1 values (10);
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*
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*/
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#include <stdio.h>
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@ -1,6 +1,6 @@
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.\" This is -*-nroff-*-
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.\" XXX standard disclaimer belongs here....
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.\" $Header: /cvsroot/pgsql/src/man/Attic/libpq.3,v 1.26 1999/04/17 17:18:41 momjian Exp $
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.\" $Header: /cvsroot/pgsql/src/man/Attic/libpq.3,v 1.27 1999/05/21 00:36:01 tgl Exp $
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.TH LIBPQ INTRO 08/08/98 PostgreSQL PostgreSQL
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.SH DESCRIPTION
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Current documentation for this topic is available in the new Programmer's Guide
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@ -266,9 +266,44 @@ PGRES_NONFATAL_ERROR,
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PGRES_FATAL_ERROR
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.fi
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.IP
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If the result status is PGRES_TUPLES_OK, then the following routines can
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be used to retrieve the tuples returned by the query.
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If the result status is PGRES_TUPLES_OK, then the
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routines described below can be used to retrieve the
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tuples returned by the query. Note that a SELECT that
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happens to retrieve zero tuples still shows PGRES_TUPLES_OK.
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PGRES_COMMAND_OK is for commands that can never return tuples.
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.PP
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.B PQresStatus
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.IP
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Converts the enumerated type returned by PQresultStatus into
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a string constant describing the status code.
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.nf
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const char *PQresStatus(ExecStatusType status);
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.fi
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.IP
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Older code may perform this same operation by direct access to a constant
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string array inside libpq,
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.nf
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extern const char * const pgresStatus[];
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.fi
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.IP
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However, using the function is recommended instead, since it is more portable
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and will not fail on out-of-range values.
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.PP
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.B PQresultErrorMessage
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.IP
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returns the error message associated with the query, or an empty string
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if there was no error.
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.nf
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const char *PQresultErrorMessage(PGresult *res);
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.fi
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.IP
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Immediately following a PQexec or PQgetResult call, PQerrorMessage
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(on the connection) will return the same string as PQresultErrorMessage
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(on the result). However, a PGresult will retain its error message
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until destroyed, whereas the connection's error message will change when
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subsequent operations are done. Use PQresultErrorMessage when you want to
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know the status associated with a particular PGresult; use PQerrorMessage
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when you want to know the status from the latest operation on the connection.
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.B PQntuples
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returns the number of tuples (instances) in the query result.
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@ -558,8 +593,7 @@ terms is readable data on the file descriptor identified by PQsocket.
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When the main loop detects input ready, it should call PQconsumeInput
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to read the input. It can then call PQisBusy, followed by PQgetResult
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if PQisBusy returns FALSE. It can also call PQnotifies to detect NOTIFY
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messages (see "Asynchronous Notification", below). An example is given
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in the sample programs section.
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messages (see "Asynchronous Notification", below).
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.PP
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A frontend that uses PQsendQuery/PQgetResult can also attempt to cancel
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@ -789,12 +823,12 @@ int PQendcopy(PGconn *conn);
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.fi
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As an example:
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.nf
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PQexec(conn, "create table foo (a int4, b name, d float8)");
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PQexec(conn, "create table foo (a int4, b char(16), d float8)");
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PQexec(conn, "copy foo from stdin");
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PQputline(conn, "3<TAB>hello world<TAB>4.5\en");
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PQputline(conn,"4<TAB>goodbye world<TAB>7.11\en");
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PQputline(conn, "3\ethello world\et4.5\en");
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PQputline(conn,"4\etgoodbye world\et7.11\en");
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\&...
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PQputline(conn,"\\.\en");
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PQputline(conn,"\e\e.\en");
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PQendcopy(conn);
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.fi
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.PP
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@ -1048,20 +1082,22 @@ main()
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* testlibpq2.c
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* Test of the asynchronous notification interface
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*
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populate a database with the following:
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CREATE TABLE TBL1 (i int4);
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CREATE TABLE TBL2 (i int4);
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CREATE RULE r1 AS ON INSERT TO TBL1 DO [INSERT INTO TBL2 values (new.i); NOTIFY TBL2];
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* Then start up this program
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* After the program has begun, do
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INSERT INTO TBL1 values (10);
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* Start this program, then from psql in another window do
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* NOTIFY TBL2;
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*
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* Or, if you want to get fancy, try this:
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* Populate a database with the following:
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*
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* CREATE TABLE TBL1 (i int4);
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*
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* CREATE TABLE TBL2 (i int4);
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*
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* CREATE RULE r1 AS ON INSERT TO TBL1 DO
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* (INSERT INTO TBL2 values (new.i); NOTIFY TBL2);
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*
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* and do
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*
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* INSERT INTO TBL1 values (10);
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*
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*/
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#include <stdio.h>
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