ecpg(1) [centos man page]

ECPG(1) 						  PostgreSQL 9.2.7 Documentation						   ECPG(1)

NAME

       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. 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. 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:

       -c
	   Automatically 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.

       -h
	   Parse a header file, this option includes otion -c.

       -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
	       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.

       --regression
	   Run in regression testing mode.

       -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 when EXEC SQL COMMIT is issued.

       -v
	   Print additional information including the version and the "include" path.

       --version
	   Print the ecpg version and exit.

       -?, --help
	   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

PostgreSQL 9.2.7						    2014-02-17								   ECPG(1)

Check Out this Related Man Page

BEGIN(7)							   SQL Commands 							  BEGIN(7)

NAME

       BEGIN - start a transaction block

SYNOPSIS

       BEGIN [ WORK | TRANSACTION ]

   INPUTS
       WORK

       TRANSACTION
	      Optional keywords. They have no effect.

   OUTPUTS
       BEGIN  This signifies that a new transaction has been started.

       WARNING: BEGIN: already a transaction in progress
	      This indicates that a transaction was already in progress.  The current transaction is not affected.

DESCRIPTION

       By  default,  PostgreSQL executes transactions in unchained mode (also known as ``autocommit'' in other database systems).  In other words,
       each user statement is executed in its own transaction and a commit is implicitly performed at the end of the statement (if  execution  was
       successful,  otherwise a rollback is done).  BEGIN initiates a user transaction in chained mode, i.e., all user statements after BEGIN com-
       mand will be executed in a single transaction until an explicit COMMIT [commit(7)] or ROLLBACK [rollback(7)].  Statements are executed more
       quickly	in  chained  mode,  because  transaction start/commit requires significant CPU and disk activity. Execution of multiple statements
       inside a transaction is also useful to ensure consistency when changing several related tables: other clients will be  unable  to  see  the
       intermediate states wherein not all the related updates have been done.

       The  default  transaction isolation level in PostgreSQL is READ COMMITTED, wherein each query inside the transaction sees changes committed
       before that query begins execution. So, you have to use SET TRANSACTION ISOLATION LEVEL SERIALIZABLE just after BEGIN if you need more rig-
       orous  transaction  isolation.  (Alternatively,	you can change the default transaction isolation level; see the PostgreSQL Administrator's
       Guide for details.)  In SERIALIZABLE mode queries will see only changes committed before the entire  transaction  began	(actually,  before
       execution of the first DML statement in the transaction).

       Transactions have the standard ACID (atomic, consistent, isolatable, and durable) properties.

   NOTES
       START TRANSACTION [start_transaction(7)] has the same functionality as BEGIN.

       Use COMMIT [commit(7)] or ROLLBACK [rollback(7)] to terminate a transaction.

       Refer to LOCK [lock(7)] for further information about locking tables inside a transaction.

       If you turn autocommit mode off, then BEGIN is not required: any SQL command automatically starts a transaction.

USAGE

       To begin a user transaction:

       BEGIN WORK;

COMPATIBILITY

   SQL92
       BEGIN  is  a  PostgreSQL language extension.  There is no explicit BEGIN command in SQL92; transaction initiation is always implicit and it
       terminates either with a COMMIT or ROLLBACK statement.

	      Note: Many relational database systems offer an autocommit feature as a convenience.

       Incidentally, the BEGIN keyword is used for a different purpose in embedded SQL. You are advised to be careful about the transaction seman-
       tics when porting database applications.

       SQL92 also requires SERIALIZABLE to be the default transaction isolation level.

SQL - Language Statements					    2002-11-22								  BEGIN(7)

Linux and UNIX Man Pages

ecpg(1) [centos man page]

Check Out this Related Man Page