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ECPG(1) | PostgreSQL 9.4.18 Documentation | ECPG(1) |
NAME¶
ecpg - embedded SQL C preprocessorSYNOPSIS¶
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. Input files preferably have the extension .pgc. The extension will be replaced by .c to determine the output file name. The output file name can also be overridden using the -o option. This reference page does not describe the embedded SQL language. See Chapter 33, ECPG - Embedded SQL in C, in the documentation 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.
-C mode
Set a compatibility mode. mode can be INFORMIX or
INFORMIX_SE.
-D symbol
Define a C preprocessor symbol.
-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.
-r option
Selects run-time behavior. Option can be one of
the following:
no_indicator
-t
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.
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.
-?
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
2018 | PostgreSQL 9.4.18 |