[英]Select distinct and random rows from one table that match a value from another table
[英]Distinct from one table, value from another
我不确定提出此问题的正确方法:我想从一个表中选择一个不同的值,然后从另一个表中获取该值。
$sql1 = mysql_query("SELECT DISTINCT County_ID FROM Customers ORDER BY County_ID ASC") or die(mysql_error());
while($row1 = mysql_fetch_array( $sql1 ))
{
$sql2 = mysql_query("SELECT County_Value FROM Counties") or die(mysql_error());
while($row2 = mysql_fetch_array( $sql2 ))
{
echo "Listed Counties : ".$row2['County_Value']." - id : ".$row1['County_ID']."<br>";
}
}
但是通过这种方式我得到了ORDER BY县ID,正确的方法是什么,以及ASC中的值列表? 谢谢。
$sql1 = mysql_query("SELECT DISTINCT County_ID, County_Value FROM Customers, Counties WHERE Counties.County_ID=Customer.County_ID ORDER BY County_Value ASC") or die(mysql_error());
PS:我应该说我想从客户表中获取列出的县列表,但是它们以id的形式存储在县表中,因此我只需要不同的countie_values ASC
也许是这样的:
SELECT CustomersSub.County_ID, County_Value
FROM (SELECT DISTINCT County_ID FROM Customers) CustomersSub
INNER JOIN Counties
ON Counties.County_ID = CustomersSub.County_ID
ORDER BY County_Value ASC
编辑-或使用汇总功能并计算每个县的客户:-
SELECT Counties.County_ID, County_Value, COUNT(Customers.County_ID) AS CustCountyCount
FROM Counties
INNER JOIN Customers
ON Counties.County_ID = Customers.County_ID
GROUP BY Counties.County_ID, County_Value
ORDER BY County_Value ASC
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