What is pro *c?

How is that开发者_StackOverflow useful? How can we access data from the database?

Pro*C is actually a pre-compiler for Oracle database access within C code.

You write your code with statements like:

int sal;
EXEC SQL SELECT salary INTO :sal FROM employees WHERE name = 'Diablo, Pax';
if (sal < 100000)
    printf ("I'm not being paid enough!\n");

intermixing regular C with Pro*C statements (as you can see) and then you run it through the Pro*C compiler.

What comes out of that is a C program which has the Pro*C statements replaced with the equivalent function calls which will do the same thing.

You then run this through a real C compiler and it gives you the executables to be run to perform whatever tasks you want.

Pro C is Oracle's embedded SQL environment for use within C and C++

http://infolab.stanford.edu/~ullman/fcdb/oracle/or-proc.html

This web page introduces the Proc *C language. It seems to be a dialect of C that makes SQL database access easier. Here's a snippet:

int main() {
    int x; char *y; int z;
    /* ... */
    EXEC SQL INSERT INTO emp(empno, ename, deptno)
        VALUES(:x, :y, :z);