What is pro * C/C ++?

Oracle supports embedding SQL statements in several advanced languages or calling Oracle database functions to access the database. They are C, COBOL, Ada, Pascal, PL/I, etc. These languages are called host languages, and the programs they develop are called Pro * programs, such as Pro * C, pro * Cobol.
Proc is available in Oracle client software and can be selected when oracle is installed.

1. What is pro * C/C ++?
An application developed by embedding SQL statements in the procedural programming language C/C ++.
2. Brief description:
The SQL used in general programming languages is called embedded SQL. The objective is that pro * C/C ++ will make C/C ++ a tool for accessing databases.

There are three methods to access the database in the Oracle database management and system;

(1) use SQL * Plus, which has SQL commands to access the database through interactive applications;

(2) applications developed by application development tools in the fourth generation language access the database. These tools include SQL * froms, Ql * reportwriter, and SQL * menu;

(3) access using SQL language or Oracle database function calls embedded in the third generation language.

Pro * C is one of the third development tools. It perfectly integrates Procedural Language C with non-procedural language SQL, and has complete process processing capabilities, it can also complete the processing tasks of any database, allowing users to program various types of reports.

The SQL language can be embedded in the Pro * C program. These SQL languages can be used to dynamically create, modify, and delete tables in the database, you can also query, insert, modify, and delete rows in a database table, and commit and roll back transactions.

PL/SQL blocks can be embedded in Pro * C programs to improve application performance, especially in network environments, which can reduce the total overhead of network transmission and processing.

2. For the program structure of Pro * C, the Pro * C program is actually a C program embedded with SQL statements or PL/SQL blocks, so its composition is similar to the C program.

Oracle 8.16 for rhlinux6.2 Pro * C Environment

1. Pro * C:

 

Oracle Database is one of the best database products and is widely used. With its in-depth application, it has become a choice for many systems to use Oracle and C to compile application systems, the knowledge of Oracle and C language interfaces should be mastered and very useful.

Pro * C is an Oracle pre-compiler which is a programming tool that embeds SQL statements into C language programs.

The pre-compiler uses the source program as the input, then translates the SQL statements embedded in the program, converts them into calls to the standard Oracle Runtime Library, and finally generates a modified source program. Compile and link the modified source program to form an executable file.

2. Environment Configuration:

 

A. Description:

The Oracle pre-compiler is installed by default or by default during Oracle 8i installation. If Pro * C is installed, the executable program proc is available in the $ ORACLE_HOME/bin path, and the corresponding pre-compiled environment without configuration. To enable the Pro * C pre-compiler to work, we must also configure the environment.

Oracle's Pro * C configures the environment by changing the option value of the pre-compiler. The basic format of precompiled commands is as follows:

Proc option name = option value source file

 

You can also change the option value to the file specified by config.

Proc options

Auto_connect	Allow automatic connection to the ops $ account
Char_map	Ing character array and string
Close_on_commit	Close all commit cursors
Codekr_c	Code type to be generated
Comp_charset	Character Set types supported by C Compiler
Config	Overwrite the system configuration file with another configuration file
Cpp_suffix	Overwrite the default C ++ file name suffix
Dbmsnative	Compatibility mode
Def_sqlcode	Generate '# define sqlcode sqlca. sqlcode' macro
Define	Define Preprocessor symbols
Durationtransaction	Set the pin duration of objects in the cache.
Dynamic	Specify oracle or ANSI dynamic SQL Semantics
Errors	Whether to send the error message to the terminal
Errtype	The name of the input file list is incorrect.
FIPS	The FIPS flag of ANSI is invalid.
Header	Specify the file extension for the precompiled title
Hold_cursor	Control cursor retention in the cursor Cache
INAME	Input File Name
Include	Including the directory path of the file
Intype	Input File Name For type information
Lines	Add the # Line command to the generated code
Lname	Overwrite the default list file name
Ltype	Data volume generated in the list file
Maxliteral	Maximum length of the generated text string
Maxopencursors	Maximum number of open cursors in the cache
Mode	The Code complies with Oracle or ANSI rules
Nls_char	Country language character variable
Nls_local	How to Control NLS character Semantics
Objects	Supported Object Types
Oname	Output file name
Region	Control the use of objective
Pagelen	Page length of List Files
Parse	Control Non-SQL code for syntax analysis
Prefetch	Number of pre-read rows during cursor open
Release_cursor	Controls the release of a cursor from the cache
Select_error	Incorrect Control Selection flag
Sqlcheck	Total amount of SQL verification during compilation time
Sys_include	Directory of the system title File
Threads	Multi-threaded applications
Type_code	Use oracle or ANSI code for dynamic SQL
Unsafe_null	Allow> null reading without variable indication
Userid	Username/password [@ dbname] connection string
Varchar	Implicit varchar structure is allowed
Version	Version of the object to be returned

 

We can use the default values for most options, but several of them need to be configured.

L config: Specify the config file of Proc. The default proc configuration file is $ ORACLE_HOME/precomp/admin/pcscfg. cfg. We can edit the config file we want to use.

L include: includes the directory path of the file, which is generally configured in the config file, which is defined by default in pcscfg. cfg.

L sys_include: directory of the system header file, which is generally configured in the config file. The default definition is in pcscfg. cfg. Note that the path of the default system header file is incorrect. For example
Sys_include = ($ ORACLE_HOME/precomp/public,/usr/include,/usr/lib/GCC-lib/i386-redhat-linux/egcs-2.91.66/include)

Luserid: User Name/password [@ dbname] connection string

B. Configuration:

The configuration is relatively simple. You only need to copy the default> config file to the path where the source program is located and modify the userid.

Use the following command to pre-compile the proc source file and output the corresponding C source program.

Proc Config = myconfg. cfg INAME = myprog. PC oname = myprog. c

Pro * C will pre-compile the proc source file specified by INAME and output the file specified by oname.

3. Editing environment:

Pre-compilation only translates the proc source file into the C source file. To compile the target file generated by compilation of different source files, you must specify the library and Oracle Interface Program (Proc program) required for the compilation) the required client shared library is distributed in many paths. For the convenience of association, Oracle provides the $ ORACLE_HOME/precomp/demo/proc/demo_proc.mk file.

Run the following command:

 

Make-F demo_proc.mk objs = "myporg. O mydb. O" EXE = myprog. e build