ecpg
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. Input files preferably 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.
This reference page does not describe the embedded SQL language. SeeChapter 33 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 forEXEC SQL TYPE.
- -Cmode
Set a compatibility mode.mode can beINFORMIX orINFORMIX_SE.
- -Dsymbol
Define a C preprocessor symbol.
- -i
Parse system include files as well.
- -Idirectory
Specify an additional include path, used to find files included viaEXEC SQL INCLUDE. Defaults are. (current directory),/usr/local/include, thePostgreSQL include directory which is defined at compile time (default:/usr/local/pgsql/include), and/usr/include, in that order.
- -ofilename
Specifies thatecpg should write all its output to the givenfilename.
- -roption
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 whenEXEC SQL COMMIT is issued.
- -v
Print additional information including the version and the "include" path.
- --version
Print theecpg version and exit.
- -?
--help Show help aboutecpg command line arguments, and exit.
Notes
When compiling the preprocessed C code files, the compiler needs to be able to find theECPG header files in thePostgreSQL 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 thelibecpg 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 usingpg_config.