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This document usesPHP Chinese website manualRelease
Now that you have an idea how to form embedded SQL C programs, you probably want to know how to compile them. Before compiling you run the file through the embeddedSQLCpreprocessor, which converts theSQLstatements you used to special function calls. After compiling, you must link with a special library that contains the needed functions. These functions fetch information from the arguments, perform theSQLcommand using thelibpqinterface, and put the result in the arguments specified for output.
The preprocessor program is calledecpgand is included in a normalPostgreSQLinstallation. Embedded SQL programs are typically named with an extension.pgc. If you have a program file calledprog1.pgc, you can preprocess it by simply calling:
ecpg prog1.pgc
This will create a file calledprog1.c. If your input files do not follow the suggested naming pattern, you can specify the output file explicitly using the-ooption.
The preprocessed file can be compiled normally, for example:
cc -c prog1.c
The generated C source files include header files from thePostgreSQLinstallation, so if you installedPostgreSQLin a location that is not searched by default, you have to add an option such as-I/usr/local/pgsql/includeto the compilation command line.
To link an embedded SQL program, you need to include thelibecpglibrary, like so:
cc -o myprog prog1.o prog2.o ... -lecpg
Again, you might have to add an option like-L/usr/local/pgsql/libto that command line.
If you manage the build process of a larger project usingmake, it might be convenient to include the following implicit rule to your makefiles:
ECPG = ecpg %.c: %.pgc $(ECPG) $<
The complete syntax of theecpgcommand is detailed inecpg.
Theecpglibrary is thread-safe by default. However, you might need to use some threading command-line options to compile your client code.
