PQputf(3)
NAME
PQputf, PQputvf - Packs a set of parameters in a PGparam for use with a parameterized query.
SYNOPSIS
#include <libpqtypes.h>
int PQputf(PGparam *param, const char *format, ...);
int PQputvf(PGparam *param, char *stmtBuf, size_t stmtBufLen,
const char *format, va_list ap);
DESCRIPTION
The PQputf() and PQputvf() functions put one or more query parameters into a PGparam using a printf style interface. Any number of parameters can be put at the same time. The format argument is a data type specifier string indicating the parameters being put, such as "%int4 %polygon". format cannot be NULL or an empty string. The variable argument list must match the format, either "..." or ap. The number of arguments required for each data type is dependant on the data type itself; built-in PostgreSQL types always require a single argument. The PQputvf() function can construct a parameterized command string from format, as long as stmtBuf and stmtBufLen have been provided. If the construction of stmtBuf is not desired, set it to NULL and set stmtBufLen to 0. When a constructed statement is desired, the contents of format will be copied to stmtBuf and all data type specifiers, like "%int4", will be replaced with $1, $2, etc... syntax. The result is a parameterized statement in synch with param and ready to be executed. For instance: if spec is "SELECT %int4 + %int4", the resulting stmtBuf would be "SELECT $1 + $2".
RETURN VALUE
On success, a non-zero value is returned. On error, zero is returned and PQgeterror(3) will contain an error message. If any put operation fails, the param is reverted back to the number of parameters it had prior to the function call; partial puts are not allowed.
EXAMPLES
Using PQputf
The example uses PQputf() to put a couple parameters into a PGparam.
PGtext text = "foobar";
PGint8 i8 = PQT_INT64CONST(1099511627776);
PGparam *param = PQparamCreate(conn);
if(!PQputf(param, "%text %int8", text, i8))
fprintf(stderr, "*ERROR: %s\n", PQgeterror());
PQparamClear(param);
Using PQputvf
The example creates an application function named execf. execf is a
wrapper to PQputvf(), as well as PQparamExec(3). It is similar to
PQexecf(). The only difference is that the PQexecf implementation uses
a smaller stack buffer and allocates heap memory when needed.
PGresult *
execf(PGconn *conn, const char *format, ...)
{
va_list ap;
char stmt[32768];
PGparam *param;
PGresult *res = NULL;
/* create the temporary PGparam */
if(!(param = PQparamCreate(conn)))
return NULL; /* PQseterror already called */
/* put the params, create the stmt and exec it */
va_start(ap, format);
if(PQputvf(param, stmt, sizeof(stmt), format, ap))
res = PQparamExec(conn, param, stmt, 1); // resfmt is binary
va_end(ap);
/* param must be cleared */
PQparamClear(param);
return res;
}
/* Example: execf will put 2 ints and execute "SELECT $1 + $2" */
PGresult *res = execf(conn, "SELECT %int4 + %int4", 100, 67);
if(!res)
fprintf(stderr, "*ERROR: %s\n", PQgeterror());
AUTHOR
A contribution of eSilo, LLC. for the PostgreSQL Database Management System. Written by Andrew Chernow and Merlin Moncure.
REPORTING BUGS
Report bugs to <[email protected]>.
COPYRIGHT
Copyright (c) 2011 eSilo, LLC. All rights reserved. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
SEE ALSO
pqt-specs(3), PQparamCreate(3), PQgeterror(3), PQseterror(3)
Opportunity
Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.
Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.
Free Software
Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.
Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.
Free Books
The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.
Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.
Education
Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.
Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.
