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我試圖讓我的頭在MySQL。我從網上的信息中學到了很多東西，但是我有點不明白JOIN如何工作以及如何適應DataTables代碼。需要幫助理解MySQL左連接和數據表
我有這樣的表結構：
而這個MySQL的語句：
SELECT leads.lead_id, leads.date_time, clients.username, courses.course_type, courses.location_name, CONCAT(first_name,' ',surname)
FROM courses
LEFT JOIN leads ON leads.lead_get_course_id = courses.course_id
LEFT JOIN clients ON clients.client_id = courses.course_get_client_id
WHERE leads.checked_by_admin = 'No'
這一切工作正常，當我測試它在Dreamweaver，但是，當我嘗試並將其應用於DataTables代碼我在'字段列表'中獲得未知列'leads.lead_id'
這裏是我的DataTable代碼：
<?php
/*
* Script: DataTables server-side script for PHP and MySQL
* Copyright: 2010 - Allan Jardine
* License: GPL v2 or BSD (3-point)
*/
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* Easy set variables
*/
/* Array of database columns which should be read and sent back to DataTables. Use a space where
* you want to insert a non-database field (for example a counter or static image)
*/
$aColumns = array(
"leads.lead_id",
"leads.date_time",
"clients.username",
"courses.course_type",
"courses.location_name",
"CONCAT(first_name,' ',surname)"
);
/* Indexed column (used for fast and accurate table cardinality) */
$sIndexColumn = "leads.lead_id";
/* DB table to use */
$sTable = "courses";
$sJoin = 'LEFT JOIN leads ON leads.lead_get_course_id = courses.course_id';
$sJoin = 'LEFT JOIN clients ON clients.client_id = courses.course_get_client_id';
/* Database connection information */
$gaSql['user'] = "root";
$gaSql['password'] = "tommy";
$gaSql['db'] = "testingsiasite";
$gaSql['server'] = "localhost";
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* If you just want to use the basic configuration for DataTables with PHP server-side, there is
* no need to edit below this line
*/
/*
* MySQL connection
*/
$gaSql['link'] = mysql_pconnect($gaSql['server'], $gaSql['user'], $gaSql['password'] ) or
die('Could not open connection to server');
mysql_select_db($gaSql['db'], $gaSql['link']) or
die('Could not select database '. $gaSql['db']);
/*
* Paging
*/
$sLimit = "";
if (isset($_GET['iDisplayStart']) && $_GET['iDisplayLength'] != '-1')
{
$sLimit = "LIMIT ".mysql_real_escape_string($_GET['iDisplayStart']).", ".
mysql_real_escape_string($_GET['iDisplayLength']);
}
/*
* Ordering
*/
if (isset($_GET['iSortCol_0']))
{
$sOrder = "ORDER BY ";
for ($i=0 ; $i<intval($_GET['iSortingCols']) ; $i++)
{
if ($_GET[ 'bSortable_'.intval($_GET['iSortCol_'.$i]) ] == "true")
{
$sOrder .= $aColumns[ intval($_GET['iSortCol_'.$i]) ]."
".mysql_real_escape_string($_GET['sSortDir_'.$i]) .", ";
}
}
$sOrder = substr_replace($sOrder, "", -2);
if ($sOrder == "ORDER BY")
{
$sOrder = "";
}
}
/*
* Filtering
* NOTE this does not match the built-in DataTables filtering which does it
* word by word on any field. It's possible to do here, but concerned about efficiency
* on very large tables, and MySQL's regex functionality is very limited
*/
/* */
/* */
$sWhere = "";
if (isset($_GET['sSearch']) && $_GET['sSearch'] != "")
{
$sWhere = "WHERE (";
for ($i=0 ; $i<count($aColumns) ; $i++)
{
$sWhere .= $aColumns[$i]." LIKE '%".mysql_real_escape_string($_GET['sSearch'])."%' OR ";
}
$sWhere = substr_replace($sWhere, "", -3);
$sWhere .= " AND checked_by_admin='No'";
$sWhere .= ')';
}else{
$sWhere = "WHERE checked_by_admin='No'";
}
/* Individual column filtering */
for ($i=0 ; $i<count($aColumns) ; $i++)
{
if ($_GET['bSearchable_'.$i] == "true" && $_GET['sSearch_'.$i] != '')
{
if ($sWhere == "")
{
$sWhere = "WHERE ";
}
else
{
$sWhere .= " AND ";
}
$sWhere .= $aColumns[$i]." LIKE '%".mysql_real_escape_string($_GET['sSearch_'.$i])."%' ";
}
}
/*
* SQL queries
* Get data to display
*/
if($sWhere != ""):
$sWhere .= " AND checked_by_admin='No'";
endif;
$sQuery = "
SELECT SQL_CALC_FOUND_ROWS ".str_replace(" , ", " ", implode(", ", $aColumns))."
FROM $sTable
$sJoin
$sWhere
$sOrder
$sLimit
";
$rResult = mysql_query($sQuery, $gaSql['link']) or die(mysql_error());
/* Data set length after filtering */
$sQuery = "
SELECT FOUND_ROWS()
";
$rResultFilterTotal = mysql_query($sQuery, $gaSql['link']) or die(mysql_error());
$aResultFilterTotal = mysql_fetch_array($rResultFilterTotal);
$iFilteredTotal = $aResultFilterTotal[0];
/* Total data set length */
$sQuery = "
SELECT COUNT(".$sIndexColumn.")
FROM $sTable
";
$rResultTotal = mysql_query($sQuery, $gaSql['link']) or die(mysql_error());
$aResultTotal = mysql_fetch_array($rResultTotal);
$iTotal = $aResultTotal[0];
/*
* Output
*/
$output = array(
"sEcho" => intval($_GET['sEcho']),
"iTotalRecords" => $iFilteredTotal, // HERE FOR MASK TOTAL ENTRY not necerrary for others customers
"iTotalDisplayRecords" => $iFilteredTotal,
"aaData" => array()
);
while ($aRow = mysql_fetch_array($rResult))
{
$row = array();
for ($i=0 ; $i<count($aColumns) ; $i++)
{
if ($aColumns[$i] == "version")
{
/* Special output formatting for 'version' column */
$row[] = ($aRow[ $aColumns[$i] ]=="0") ? '-' : $aRow[ $aColumns[$i] ];
}
else if ($aColumns[$i] != ' ')
{
/* General output */
$row[] = $aRow[ $aColumns[$i] ];
}
}
$row[] = "<span style='cursor:pointer'><img src='../images/more-info.png' alt='more info' onClick='javascript:my_onclick({$row[0]});'/></span>";
$row[] = "<a href='../leads/actions/approve-lead.php?lead_id={$row[0]}'><img src='../images/approve.png' alt='' /></a>";
$row[] = "<a href='../leads/actions/delete-lead.php?lead_id={$row[0]}' class='delete_link'><img src='../images/delete.png' alt='' /></a>";
$output['aaData'][] = $row;
}
echo json_encode($output);
?>
爲什麼林收到此錯誤的任何光線將是巨大的！
用'SELECT leads.lead_id FROM leads'會發生什麼？ –
您是否嘗試使用「lead_id」而不是「leads.lead_id」？ – Arfeen
順便提一下，外鍵通常被命名爲「 _id」。所以'courses.course_get_client_id'可以簡單地命名爲'courses.client_id'。 –
halfer