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. Input files
preferrably have the extension .pgc, in which
case the extension will be replaced by .c to
determine the output file name. If the extension of the input file
is not .pgc, then the output file name is
computed by appending .c to the full file name.
The output file name can also be overridden using the
-o option.
ecpg accepts the following command-line
arguments:
-c
Automatically generate C code from SQL code. Currently, this
works for EXEC SQL TYPE.
-D symbol
Define a C preprocessor symbol.
-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.
-t
Turn on autocommit of transactions. In this mode, each query is
automatically committed unless it is inside an explicit
transaction block. In the default mode, queries are committed
only when EXEC SQL COMMIT is issued.
-v
Print additional information including the version and the
include path.
---help
Show a brief summary of the command usage, then exit.
--version
Output version information, then 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, one 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
flags -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.
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
See Also
PostgreSQL Programmer's Guide for a more
detailed description of the embedded SQL interface
