Example: Create functions
private static int exec_callback (int n_columns, string[] values, string[] column_names) {
for (int i = 0; i < n_columns; i++) {
print ("%s: %s\n", column_names[i], values[i]);
}
return 0;
}
private static void sqlite_func_my_strlen (Sqlite.Context context, Sqlite.Value[] values) {
// Parameter validation:
assert (values.length == 1); // checked by sqlight
if (values[0].to_type () != Sqlite.TEXT) {
context.result_error ("Unexpected parameter type", Sqlite.MISMATCH);
return ;
}
// Get the parameter:
string text = values[0].to_text ();
// Store the return value:
context.result_int (text.length);
}
public static int main (string[] args) {
Sqlite.Database db;
string errmsg;
// Open/Create a database:
int ec = Sqlite.Database.open ("test.db", out db);
if (ec != Sqlite.OK) {
stderr.printf ("Can't open database: %d: %s\n", db.errcode (), db.errmsg ());
return -1;
}
// Register a function:
db.create_function ("my_strlen", 1, Sqlite.UTF8, null, sqlite_func_my_strlen, null, null);
// Call our function:
string query = "SELECT my_strlen ('Hello, world!');";
ec = db.exec (query, exec_callback, out errmsg);
if (ec != Sqlite.OK) {
stderr.printf ("Error: %s\n", errmsg);
return -1;
}
// Output: (see exec_callback)
// ``my_strlen ('Hello, world'): 13``
return 0;
}
valac --pkg sqlite3 create-function.vala
See:
