GDSQL -- The "Good SQL" library

What is does / will do

1. Define a uniform C API to access a relational database using prepared statements.
2. Support multiple databases, at the same time from a single program.
3. Simplify your life.

What is does not do / will never do

1. Provide an object-relational bridge.
2. Hide different SQL syntaxes.
3. Eat up your memory and/or CPU.

What does it look like

This is an example of accessing a PostgreSQL database. We read rows from table people, which has at least these columns:

• id: the integer primary key
• name: a string with the person's name.
• birth: a datetime with the person's birthday.

Here is the code, without any error checking. This exact same code should work with other databases (except for any differences in the SQL syntax).

gdsql gdsql = 0;
gdsql_db db = 0;
gdsql_stmt stmt = 0;

gdsql = gdsql_init();

db = gdsql_alloc_db(gdsql, GDSQL_DB_POSTGRES);
gdsql_db_set_host(db, "localhost");
gdsql_db_set_port(db, 5432);
gdsql_db_set_name(db, "db");
gdsql_db_set_user(db, "user");
gdsql_db_set_password(db, "password");
gdsql_db_open(db);

stmt = gdsql_db_alloc_stmt(db);
gdsql_stmt_set_query(stmt,
                     "SELECT id,name FROM people WHERE birth BETWEEN $1 AND $2 ORDER BY id;");

double d1 = gdsql_cal2jul(1970,  1,  1,  0,  0,  0);
double d2 = gdsql_cal2jul(2004, 12, 31, 23, 59, 59);
        
gdsql_stmt_bindp_date(stmt, 1, d1);
gdsql_stmt_bindp_date(stmt, 2, d2);
    
int id;
char name[100];

gdsql_stmt_bindr_int   (stmt, 1, &id);
gdsql_stmt_bindr_string(stmt, 2, name, 100);

int n = 0;
while (1) {
    id = -1;
    name[0] = '\0';

    int ret = gdsql_stmt_step(stmt);
    if (ret != 0)
        break;

    if (gdsql_stmt_is_column_null(stmt, 2))
        strcpy(name, "NULL");

    printf("Row %d: %d|%s\n",
           ++n, id, name);
}

gdsql_stmt_finalize(stmt);
gdsql_db_free_stmt(stmt);
gdsql_db_close(db);
gdsql_free_db(db);
gdsql_fini(gdsql);

What databases are supported

There already is support for SQLite, PostgreSQL and MySQL.

I believe the library will be ready for a v1.0 release when it also provides support for Oracle, Sybase, DB2 and SQL Server.

What the name means

The name gdsql means "Good SQL". The fact that GD are also the initials of the original author is purely coincidental...