php mysqli_query - 返回值
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mysqli_query - return values
提问by MadLarkin
I am using the PHP function mysqli_queryto run a SELECTquery.
我正在使用 PHP 函数mysqli_query来运行SELECT查询。
What does mysqli_queryreturn if the query runs successfully, but the query finds no matches?
mysqli_query如果查询运行成功，但查询没有找到匹配项，会返回什么？
回答by AgentConundrum
Per the manual:
根据手册：
Returns FALSE on failure. For successful SELECT, SHOW, DESCRIBE or EXPLAIN queries mysqli_query() will return a mysqli_result object. For other successful queries mysqli_query() will return TRUE.
失败时返回 FALSE。对于成功的 SELECT、SHOW、DESCRIBE 或 EXPLAIN 查询，mysqli_query() 将返回一个 mysqli_result 对象。对于其他成功的查询，mysqli_query() 将返回 TRUE。
A query that runs but returns no results is still considered a "successful query", since the query did run in the database and an empty result set is a legitimate response. This means the query will still return a mysqli_resultobject, and if you check its row count (either via $result->num_rowsin the object-oriented style or mysqli_num_rows($result)in the procedural style) it will return 0.
运行但不返回结果的查询仍被视为“成功查询”，因为该查询确实在数据库中运行并且空结果集是合法响应。这意味着查询仍然会返回一个mysqli_result对象，如果你检查它的行数（通过$result->num_rows面向对象风格或mysqli_num_rows($result)过程风格），它将返回 0。
回答by Niels
A Mysqli_queryobject, than you can use mysqli_num_rowsto count the number of rows returned. So:
一个Mysqli_query对象，比你可以使用mysqli_num_rows来计算返回的行数。所以：
if(mysqli_num_rows($query) > 0 ){
// Do something
}
回答by Tommaso Belluzzo
if ($result = $mysqli->query("SELECT * FROM data"))
{
$count = $result->num_rows;
printf("Result set has %d rows.\n", $count);
$result->close();
}
From reference:
从参考：
Returns FALSE on failure. For successful SELECT, SHOW, DESCRIBE or EXPLAIN queries mysqli_query() will return a mysqli_result object. For other successful queries mysqli_query() will return TRUE.
失败时返回 FALSE。对于成功的 SELECT、SHOW、DESCRIBE 或 EXPLAIN 查询，mysqli_query() 将返回一个 mysqli_result 对象。对于其他成功的查询，mysqli_query() 将返回 TRUE。
