看似简单：检查一个查询中是否从MySQL返回数据

Question

Here is a simple scenario I am contemplating. I have a query that is executed on a MySQL database from PHP. I would like to check if any data was returned from the query. However, in order to perform that check, it pulls out one of the rows of returned data.

Look at this example, and its comments:

$booksGrabber = ("SELECT * FROM table");

if (!$booksGrabber) {
  //Query failed, perhaps a syntax error
  exit;
}

if (!mysql_result($booksGrabber, 0)) {
  //No data was returned :(
  exit;
}

while ($book = mysql_fetch_assoc($booksGrabber)) {
  //mysql_result() stole the first row of returned data
  //So if I was expecting the loop to display 4 results,
  //I only get 3...
}

How can I check if data was returned from the database without running two queries (one to check, the other to display all of the data) or having one of the rows stolen?

Answer 1

Use mysql_num_rows. It was as simple as it looked.

EDIT: If you want more complicated, add mysql_data_seek($booksGrabber,0).