ecpg(1) PostgreSQL 15.7 Documentation ecpg(1)
NAME
ecpg - embedded SQL C preprocessor
SYNOPSIS
ecpg [option...] file...
DESCRIPTION
ecpg is the embedded SQL preprocessor for C programs. It converts C
programs with embedded SQL statements to normal C code by replacing the
SQL invocations with special function calls. The output files can then
be processed with any C compiler tool chain.
ecpg will convert each input file given on the command line to the
corresponding C output file. If an input file name does not have any
extension, .pgc is assumed. The file's extension will be replaced by .c
to construct the output file name. But the output file name can be
overridden using the -o option.
If an input file name is just -, ecpg reads the program from standard
input (and writes to standard output, unless that is overridden with
-o).
This reference page does not describe the embedded SQL language. See
Chapter 36 for more information on that topic.
OPTIONS
ecpg accepts the following command-line arguments:
-c
Automatically generate certain C code from SQL code. Currently,
this works for EXEC SQL TYPE.
-C mode
Set a compatibility mode. mode can be INFORMIX, INFORMIX_SE, or
ORACLE.
-D symbol[=value]
Define a preprocessor symbol, equivalently to the EXEC SQL DEFINE
directive. If no value is specified, the symbol is defined with the
value 1.
-h
Process header files. When this option is specified, the output
file extension becomes .h not .c, and the default input file
extension is .pgh not .pgc. Also, the -c option is forced on.
-i
Parse system include files as well.
-I directory
Specify an additional include path, used to find files included via
EXEC SQL INCLUDE. Defaults are . (current directory),
/usr/local/include, the PostgreSQL include directory which is
defined at compile time (default: /usr/local/pgsql/include), and
/usr/include, in that order.
-o filename
Specifies that ecpg should write all its output to the given
filename. Write -o - to send all output to standard output.
-r option
Selects run-time behavior. Option can be one of the following:
no_indicator
Do not use indicators but instead use special values to
represent null values. Historically there have been databases
using this approach.
prepare
Prepare all statements before using them. Libecpg will keep a
cache of prepared statements and reuse a statement if it gets
executed again. If the cache runs full, libecpg will free the
least used statement.
questionmarks
Allow question mark as placeholder for compatibility reasons.
This used to be the default long ago.
-t
Turn on autocommit of transactions. In this mode, each SQL command
is automatically committed unless it is inside an explicit
transaction block. In the default mode, commands are committed only
when EXEC SQL COMMIT is issued.
-v
Print additional information including the version and the
"include" path.
--version
Print the ecpg version and exit.
-?
--help
Show help about ecpg command line arguments, and exit.
NOTES
When compiling the preprocessed C code files, the compiler needs to be
able to find the ECPG header files in the PostgreSQL include directory.
Therefore, you might have to use the -I option when invoking the
compiler (e.g., -I/usr/local/pgsql/include).
Programs using C code with embedded SQL have to be linked against the
libecpg library, for example using the linker options
-L/usr/local/pgsql/lib -lecpg.
The value of either of these directories that is appropriate for the
installation can be found out using pg_config(1).
EXAMPLES
If you have an embedded SQL C source file named prog1.pgc, you can
create an executable program using the following sequence of commands:
ecpg prog1.pgc
cc -I/usr/local/pgsql/include -c prog1.c
cc -o prog1 prog1.o -L/usr/local/pgsql/lib -lecpg
PostgreSQL 15.7 2024 ecpg(1)
postgresql 15.7 - Generated Wed May 22 09:51:46 CDT 2024