How embedded SQL program in C gets executed as in the backend?

When a C program is written using Embedded SQL, (eg: lets assume that a table is created with values inserted), how it gets executed in the backend before displaying the output table in the frontend? Help is appreciated...!

Solution

SQL statements are embedded into host language, say for example: C
So, we have SQL statements and C language statements and in this case, SQL statements are embedded in C source code.
Host Language code is compiled by Host compiler, Embedded language code is first preprocessed by embedded SQL preprocessor and output of preprocessor is nothing but C code, which are C-library calls, which are compiled by C compiler.

As we have directives like #include, #define for a C preprocessor, we have few directives for SQL embedded preprocessor like: EXEC SQL begin declare section and EXEC SQL end declare section

EXEC SQL begin declare section;
int cno;
varchar cname[31];
varchar street[31];
int zip;
char phone[13];
EXEC SQL end declare section;

Here, the SQL embedded preprocessor conversion is shown below:-

/* varchar cname[31]; */
struct {
unsigned short len;
unsigned char arr[31];
} cname;

This is just to give an idea of how embedded SQL works. For more detailed presentation, you may refer to Oracle-8 Embedded SQL