ecpg
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. SeeChapter 34 for more information on that topic.
Options
ecpg accepts the following command-line arguments:
-cAutomatically generate certain C code from SQL code. Currently, this works for
EXEC SQL TYPE.-CmodeSet a compatibility mode.
modecan beINFORMIX,INFORMIX_SE, orORACLE.-Dsymbol[=value]Define a preprocessor symbol, equivalently to the
EXEC SQL DEFINEdirective. If novalueis specified, the symbol is defined with the value1.-hProcess header files. When this option is specified, the output file extension becomes
.hnot.c, and the default input file extension is.pghnot.pgc. Also, the-coption is forced on.-iParse system include files as well.
-IdirectorySpecify an additional include path, used to find files included via
EXEC SQL INCLUDE. Defaults are.(current directory),/usr/local/include, thePostgres Pro include directory which is defined at compile time (default:/usr/local/pgsql/include), and/usr/include, in that order.-ofilenameSpecifies that
ecpgshould write all its output to the givenfilename. Write-o -to send all output to standard output.-roptionSelects run-time behavior.
Optioncan be one of the following:no_indicatorDo not use indicators but instead use special values to represent null values. Historically there have been databases using this approach.
preparePrepare 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.
questionmarksAllow question mark as placeholder for compatibility reasons. This used to be the default long ago.
-tTurn 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 COMMITis issued.-vPrint additional information including the version and the "include" path.
--versionPrint theecpg version and exit.
-?--helpShow 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 thePostgres Pro 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.
Examples
If you have an embedded SQL C source file namedprog1.pgc, you can create an executable program using the following sequence of commands:
ecpg prog1.pgccc -I/usr/local/pgsql/include -c prog1.ccc -o prog1 prog1.o -L/usr/local/pgsql/lib -lecpg