我有一个电子邮件列表，其中有很多重复的数据，我想合并某些列中有重复数据的行。
这是我的表格:
autoid,title,lastname,firstname,middlename,prefix,
fulladdress,address1,address2,
city,state,zip,country,county,phone1,phone2,email,id, ts
我想根据email和phone1合并重复的行。如果这两行中的内容是相同的，那么我想要合并这两行，然后填上空白，然后去掉第二行。autoid值较低的行中的数据将优先于id值较高的行。
如果我们能做到这一点与一个单一的mysql查询将是伟大的，但如果我们必须使用PHP，也将工作。
您可以使用类似
这样的命令将多行合并为单个行GROUP BY email, phone1
如果你插入这个，你会得到任意一个组合行。如果您希望值优先于NULL字段，您可以使用聚合函数，例如MIN:
SELECT MIN(title), MIN(lastname), …
FROM tableName
GROUP BY email, phone1
但是这会决定为每一行分别取哪个值。以您描述的方式合并行的查询在MySQL中是相当棘手的。您可以有一个查询，列出所有行的匹配列的顺序，然后降序autoid，使用用户变量来填补空白。但是，不填补不匹配行的空白会很困难，因此为每个匹配对设置一个子查询可能会更好。除了性能和查询的可读性之外，总的来说，您最好使用PHP解决方案。
在PHP中，事情应该相当简单:使用
查询数据库ORDER BY email, phnone1, autoid ASC
，然后在PHP端，对于从数据库中读取的每一行，检查它是否与之前在两个特定列中读取的行匹配。如果是，遍历列，替换null s。我现在不是一个PHP程序员，所以其他人可能更适合为这个编写代码片段。
我们真的不喜欢在StackOverflow上提供完整的代码解决方案，通常我们会帮助您编写自己的代码，但我不确定我是否可以在没有实际编写代码的情况下解释所有步骤，所以这里是一些入门代码。
这是未经测试的原始代码
首先复制你现有的表，直到我们知道这段代码不会损害或丢失你现有的数据，在一个副本上做所有的事情，然后一旦它被熨平，你已经验证它将正常工作，然后应用到正确的表
使用:
创建副本CREATE TABLE EmailListCopy LIKE EmailList;
INSERT EmailListCopy SELECT * FROM EmailList;
<?php
//This script will first query the table for ALL results, store them in arrays,
//then loop through the arrays to search the table for duplicates using individual
//sql queries and then compare the results, update the entry as needed and delete the
//duplicate row. THIS CODE IS NOT OPTIMIZED!! DO NOT RUN CONTINUOUSLY!! This should be
//used for OCCASIONAL merging ONLY!! i.e. Once-a-day or once-a-week etc...
$result="";
$duplicatesFound;
//Setup arrays to hold the original query information
$autoidArray = array();
$titleArray = array();
$lastnameArray = array();
$firstnameArray = array();
$middlenameArray = array();
$prefixArray = array();
$fulladdressArray = array();
$address1Array = array();
$address2Array = array();
$cityArray = array();
$stateArray = array();
$zipArray = array();
$countryArray = array();
$countyArray = array();
$phone1Array = array();
$phone2Array = array();
$emailArray = array();
$idArray = array();
$tsArray = array();
$link=mysqli_connect($hostname,$dbname,$password,$username);
if(mysqli_connect_errno())
{
$result="Error connecting to database: ".mysqli_connect_error();
}
else
{
$stmt=mysqli_prepare($link,"SELECT autoid,title,lastname,firstname,middlename,prefix,fulladdress,address1,address2,city,state,zip,country,county,phone1,phone2,email,id,ts FROM " . $table);
mysqli_stmt_execute($stmt);
mysqli_stmt_bind_result($stmt, $autoid, $title, $lastname, $firstname, $middlename, $prefix, $fulladdress, $address1, $address2, $city, $state, $zip, $country, $county, $phone1, $phone2, $email, $id, $ts);
if(mysqli_stmt_errno($stmt))
{
$result="Error executing SQL statement: ".mysqli_stmt_error($stmt);
}
else
{
mysqli_stmt_store_result($stmt);
if(mysqli_stmt_num_rows($stmt)==0)
{
$result="0 rows returned (Empty table)";
}
else
{
while(mysqli_stmt_fetch($stmt))
{
//Load results into arrays
array_push($autoidArray, $autoid);
array_push($titleArray, $title);
array_push($lastnameArray, $lastname);
array_push($firstnameArray, $firstname);
array_push($middlenameArray, $middlename);
array_push($prefixArray, $prefix);
array_push($fulladdressArray, $fulladdress);
array_push($address1Array, $address1);
array_push($address2Array, $address2);
array_push($cityArray, $city);
array_push($stateArray, $state);
array_push($zipArray, $zip);
array_push($countryArray, $country);
array_push($countyArray, $county);
array_push($phone1Array, $phone1);
array_push($phone2Array, $phone2);
array_push($emailArray, $email);
array_push($idArray, $id);
array_push($tsArray, $ts);
}
}
mysqli_stmt_free_result($stmt);
}
for($i=0;$i<count($emailArray);$i++)
{
$duplicatestmt=mysqli_prepare($link,"SELECT autoid,title,lastname,firstname,middlename,prefix,fulladdress,address1,address2,city,state,zip,country,county,phone1,phone2,email,id,ts FROM " . $table . " WHERE email=? OR phone1=?");
mysqli_stmt_bind_param($duplicatestmt, 'si', $emailArray[$i], $phone1Array[$i]);
mysqli_stmt_execute($duplicatestmt);
mysqli_stmt_bind_result($duplicatestmt, $autoid, $title, $lastname, $firstname, $middlename, $prefix, $fulladdress, $address1, $address2, $city, $state, $zip, $country, $county, $phone1, $phone2, $email, $id, $ts);
if(mysqli_stmt_errno($duplicatestmt))
{
$result="Error executing SQL statement: ".mysqli_stmt_error($duplicatestmt);
}
else
{
mysqli_stmt_store_result($duplicatestmt);
if(mysqli_stmt_num_rows($duplicatestmt)==0)
{
//NO Duplicate entry found, loop again;
echo "<p>No Dublicate Found</p>";
}
else
{
while(mysqli_stmt_fetch($duplicatestmt))
{
//Found a duplicate
echo "<p>Dublicate Found</p>";
if($autoid > $autoidArray[$i])
{
if($email=="" && $phone1=="")
{
echo "<p>Both email and phone1 are empty. Skipping...</p>";
else
{
$duplicatesFound++;
//The autoid of the duplicate just found is greater then the autoid of the
//one used to find the duplicate (older). Therefor update the entry and remove the
//duplicate
//
//This checks each of the values and if the lower autoid one is blank, then will add the
//value to the table in the lower autoid row
//NOTE:** If having any problems with the queries below try removing the single quotes -> ' <- from any "autoid=" portion of the query
if($titleArray[$i]==""){mysqli_query($link,"UPDATE EmailListCopy SET title='".$title."' WHERE autoid='".$autoidArray[$i]."'");}
if($lastnameArray[$i]==""){mysqli_query($link,"UPDATE EmailListCopy SET title='".$firstname."' WHERE autoid='".$autoidArray[$i]."'");}
if($firstnameArray[$i]==""){mysqli_query($link,"UPDATE EmailListCopy SET title='".$lastname."' WHERE autoid='".$autoidArray[$i]."'");}
if($middlenameArray[$i]==""){mysqli_query($link,"UPDATE EmailListCopy SET title='".$middlename."' WHERE autoid='".$autoidArray[$i]."'");}
if($prefixArray[$i]==""){mysqli_query($link,"UPDATE EmailListCopy SET title='".$prefix."' WHERE autoid='".$autoidArray[$i]."'");}
if($fulladdressArray[$i]==""){mysqli_query($link,"UPDATE EmailListCopy SET title='".$fulladdress."' WHERE autoid='".$autoidArray[$i]."'");}
if($address1Array[$i]==""){mysqli_query($link,"UPDATE EmailListCopy SET title='".$address1."' WHERE autoid='".$autoidArray[$i]."'");}
if($address2Array[$i]==""){mysqli_query($link,"UPDATE EmailListCopy SET title='".$address2."' WHERE autoid='".$autoidArray[$i]."'");}
if($cityArray[$i]==""){mysqli_query($link,"UPDATE EmailListCopy SET title='".$city."' WHERE autoid='".$autoidArray[$i]."'");}
if($stateArray[$i]==""){mysqli_query($link,"UPDATE EmailListCopy SET title='".$state."' WHERE autoid='".$autoidArray[$i]."'");}
if($zipArray[$i]==""){mysqli_query($link,"UPDATE EmailListCopy SET title='".$zip."' WHERE autoid='".$autoidArray[$i]."'");}
if($countryArray[$i]==""){mysqli_query($link,"UPDATE EmailListCopy SET title='".$country."' WHERE autoid='".$autoidArray[$i]."'");}
if($countyArray[$i]==""){mysqli_query($link,"UPDATE EmailListCopy SET title='".$county."' WHERE autoid='".$autoidArray[$i]."'");}
if($phone1Array[$i]==""){mysqli_query($link,"UPDATE EmailListCopy SET title='".$phone1."' WHERE autoid='".$autoidArray[$i]."'");}
if($phone2Array[$i]==""){mysqli_query($link,"UPDATE EmailListCopy SET title='".$phone2."' WHERE autoid='".$autoidArray[$i]."'");}
if($emailArray[$i]==""){mysqli_query($link,"UPDATE EmailListCopy SET title='".$email."' WHERE autoid='".$autoidArray[$i]."'");}
if($idArray[$i]==""){mysqli_query($link,"UPDATE EmailListCopy SET title='".$id."' WHERE autoid='".$autoidArray[$i]."'");}
if($tsArray[$i]==""){mysqli_query($link,"UPDATE EmailListCopy SET title='".$ts."' WHERE autoid='".$autoidArray[$i]."'");}
//Now that it has been updated, delete the duplicate entry
mysqli_query($link, "DELETE FROM EmailListCopy WHERE autoid='".$autoid."'");
echo "<p>Duplicate to be updated DELETE FROM EmailListCopy WHERE autoid='".$autoid."'</p>";
}
}
else
{
//The duplicate autoid is lower then the one used to query either an entry we already but is still in the arrays, or something else.
//This is to be skipped.
echo "<p>Duplicate not to be updated</p>";
}
}
$result="Merged ".$duplicatesFound." rows.";
}
mysqli_stmt_free_result($stmt);
}
}
mysqli_stmt_close($duplicatestmt);
mysqli_stmt_close($stmt);
mysqli_close($link);
}
echo $result;
?>