我想在mysql查询中缺少数据时显示关系数据
我想显示关系数据,当mysql查询中缺少数据时,我有以下查询我想在mysql查询中缺少数据时显示关系数据,mysql,sql,database,Mysql,Sql,Database,我想显示关系数据,当mysql查询中缺少数据时,我有以下查询 SELECT u.user_email, um1.value AS school, um.value AS postcode FROM `wp_users` AS u, `wp_bp_xprofile_data` AS um, `wp_bp_xprofile_data` AS um1 WHERE u.ID = um.user_id AND u.ID = um1.user_id AND um.field_id =322 AND um1.
SELECT u.user_email, um1.value AS school, um.value AS postcode
FROM `wp_users` AS u, `wp_bp_xprofile_data` AS um, `wp_bp_xprofile_data` AS um1
WHERE u.ID = um.user_id
AND u.ID = um1.user_id
AND um.field_id =322
AND um1.field_id =69
这会显示电子邮件地址、学校名称和邮政编码。我想弄清楚的是,如果学校或邮政编码不在数据库中,如何获取所有电子邮件,即即使数据丢失,也显示值
干杯,
里奇我相信你知道。
SELECT u.user_email
, um1.value AS school
, um.value AS postcode
FROM `wp_users` AS u
LEFT JOIN `wp_bp_xprofile_data` AS um
ON u.ID = um.user_id
AND um.field_id = 322
LEFT JOIN `wp_bp_xprofile_data` AS um1
ON u.ID = um1.user_id
AND um1.field_id = 69