Prepared Statements


This code example has been simplified to make it easier to read, the connection and error handling code has been removed.

In this example a basic select query has been defined which has one element to replace using the ‘?’ character. The statement is prepared using drizzle_stmt_prepare() and we can get the number of parameters the server is expecting with drizzle_stmt_param_count(). In this example we know that there is only one parameter required so we send one INT type parameter using drizzle_stmt_set_int() stating that this is parameter 0 and a signed value.

Once the parameters have been provided the statement is executed using drizzle_stmt_execute() and the results buffered using drizzle_stmt_buffer(). Once buffered the row count can be obtained using drizzle_stmt_row_count().

Finally we get the result data. A call to drizzle_stmt_fetch() gets the next row from either the network or the buffer (the buffer in this case). The int data is retrieved using drizzle_stmt_get_int(), a call for each column in the row (in example the table only has one column) is made using the drizzle_stmt_get_ functions.

When we are done the statement is closed and cleaned up using drizzle_stmt_close(). It can also be reused with drizzle_stmt_reset() or executed again with drizzle_stmt_execute() (this is useful for inserts).


drizzle_stmt_st *stmt;
const char *query= "select * from libdrizzle.t1 where a > ?";
stmt= drizzle_stmt_prepare(con, query, strlen(query), &ret);

printf("Params: %" PRIu16 "\n", drizzle_stmt_param_count(stmt));

uint32_t val= 1;
ret = drizzle_stmt_set_int(stmt, 0, val, false);

ret = drizzle_stmt_execute(stmt);

ret = drizzle_stmt_buffer(stmt);

printf("Rows found: %" PRIu64 "\n", drizzle_stmt_row_count(stmt));
while (drizzle_stmt_fetch(stmt) != DRIZZLE_RETURN_ROW_END)
  uint32_t res_val;
  res_val= drizzle_stmt_get_int(stmt, 0, &ret);
  printf("Got value: %" PRIu32 "\n", *res_val);
ret = drizzle_stmt_close(stmt);