如何使用 ODBC 连接在 PHP 中获取结果集中的计数或行数？
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How to Get The Count or The Number Of Rows In A Result Set In PHP using ODBC Connection?
提问by TopDeveloper
While I build a web page in My PHP web application, My Connection works ok but When I want to get the count of rows of the SELECT Statement I used in my query, It gives me -1 !! although my result set has about 10 rows.
当我在我的 PHP Web 应用程序中构建一个网页时，我的连接工作正常，但是当我想获取我在查询中使用的 SELECT 语句的行数时，它给了我 -1 ！虽然我的结果集大约有 10 行。
I would like to get the actual number of result set rows. I searched the PHP Manual & documentation but I do not find a direct way like a Count function or something like that.
我想获得结果集行的实际数量。我搜索了 PHP 手册和文档，但没有找到像 Count 函数或类似的直接方法。
I wonder if I have to make a Count(*) SQL Statement in another query and attach it to my Connection to get the Count of Rows ?
我想知道是否必须在另一个查询中创建一个 Count(*) SQL 语句并将其附加到我的 Connection 以获取行数？
Does any one knows an easy and direct way to get that ?
有没有人知道一种简单而直接的方法来获得它？
the odbc_num_rows function always gives -1 in result so I can not get the actual number of rows.
odbc_num_rows 函数总是在结果中给出 -1，所以我无法获得实际的行数。
My Programming langauge is PHP and My Database Engine is Sybase and The Way to connect to Database is ODBC.
我的编程语言是 PHP，我的数据库引擎是 Sybase，连接数据库的方式是 ODBC。
Here are you the Code I used:-
这是我使用的代码：-
<?PHP
//PHP Code to connect to a certain database using ODBC and getting information from it
//Determining The Database Connection Parameters
$database = 'DatabaseName';
$username = 'UserName';
$password = 'Password';
//Opening the Connection
$conn = odbc_connect($database,$username,$password);
//Checking The Connection
if (!$conn)
{
exit("Connection Failed: " . $conn);
}
//Preparing The Query
$sql = "SELECT * FROM Table1 WHERE Field1='$v_Field1'";
//Executing The Query
$rs = odbc_exec($conn,$sql);
//Checking The Result Set
if (!$rs)
{
exit("Error in SQL");
}
echo "<p align='Center'><h1>The Results</h1></p>";
while ( odbc_fetch_row($rs) )
{
$field1 = odbc_result($rs,1);
$field2 = odbc_result($rs,2);
$field3 = odbc_result($rs,3);
echo "field1 : " . $field1 ;
echo "field2 : " . $field2 ;
echo "field3 : " . $field3 ;
}
$RowNumber = odbc_num_rows($rs);
echo "The Number of Selected Rows = " . $RowsNumber ;
//Closing The Connection
odbc_close($conn);
?>
Thanks for your Help :)
感谢您的帮助 ：）
回答by Pekka
odbc_num_rowsseems to be reliable for INSERT, UPDATE, and DELETE queries only.
odbc_num_rows似乎只对 INSERT、UPDATE 和 DELETE 查询可靠。
The manualsays:
该手册说：
Using odbc_num_rows() to determine the number of rows available after a SELECT will return -1 with many drivers.
使用 odbc_num_rows() 确定 SELECT 后可用的行数将返回 -1 与许多驱动程序。
one way around this behaviour is to do a COUNT(*)in SQL instead. See herefor an example.
解决此行为的一种方法是COUNT(*)在 SQL 中执行 a 。有关示例，请参见此处。
回答by Ramin Rezazadeh
in php.net:
在 php.net 中：
The easy way to count the rows in an odbc resultset where the driver returns -1 is to let SQL do the work:
计算驱动程序返回 -1 的 odbc 结果集中的行数的简单方法是让 SQL 来完成这项工作：
<?php
$conn = odbc_connect("dsn", "", "");
$rs = odbc_exec($conn, "SELECT Count(*) AS counter FROM tablename WHERE fieldname='" . $value . "'");
$arr = odbc_fetch_array($rs);
echo $arr['counter'];
?>
回答by PerformanceDBA
On what basis, do you expect odbc_num_rowsto return anything other than -1 ?
在什么基础上，您希望odbc_num_rows返回 -1 以外的任何内容？
We have the fact from the manuals, that OBDC does not support @@ROWCOUNT / odbc_num_rows. So there is no basis for expecting that it "should" return anything other than that which is documented, -1 in all circumstances.
我们从手册中得知，OBDC 不支持@@ROWCOUNT / odbc_num_rows. 因此，没有依据期望它“应该”返回除记录之外的任何内容，在所有情况下都为 -1。
Even if you used Sybase directly (instead of via ODBC), you would have the same "problem".
即使您直接使用 Sybase（而不是通过 ODBC），您也会遇到同样的“问题”。
odbc_num_rowsreturns@@ROWCOUNT, which is the rows inserted/updated/deleted by the immediately preceding command. -1 is the correct, documented value, if the immediately preceding command is notinsert/update/delete.It has nothing to do with rows in a table.
odbc_num_rows返回@@ROWCOUNT，它是由前一个命令插入/更新/删除的行。-1 是正确的记录值，如果前一个命令不是插入/更新/删除。它与表中的行无关。
Use another batch, and either one of the documentedmethods to obtain rows in a table, and load the value into a variable:
使用另一个批处理和任一记录的方法来获取table 中的行，并将值加载到变量中：
- SELECT @Count = COUNT(*) -- slow, requires I/O
or - SELECT @Count = ROW_COUNT(db_id, object_id) -- very fast, no I/O
- SELECT @Count = COUNT(*) -- 慢，需要 I/O
或 - SELECT @Count = ROW_COUNT(db_id, object_id) -- 非常快，没有 I/O
Then interrogate the result array, to obtain the variable, not odbc_num_rows, which will continue returning -1.
然后查询结果数组，获取变量， not odbc_num_rows，它将继续返回-1。
