Question

我有两张桌子：

表1：＆＃39; user_fields＆＃39;

id  name
1   age
2   birthdate
3   firstname

表2：＆＃39; user_data＆＃39;

user_id user_field_id value
22          1           50
22          2           01.01.1990
22          3           Peter
25          1           33
25          2           05.08.1970
25          3           Steve

现在我想创建一个sql语句，显示每个user_id的名字和生日

示例行：

22    Peter    01.01.1990
25    Steve    05.08.1970

选择应该如何？非常感谢！

Answer 1

您需要加入表格（如果您不想对值进行硬编码），然后执行汇总：

SELECT  ud.user_id,
        MIN(CASE WHEN uf.name = 'firstname' THEN ud.value END) as firstname,
        MIN(CASE WHEN uf.name = 'birthday' THEN ud.value END) as birthday
FROM user_data ud
INNER JOIN user_fields uf
    ON ud.user_field_id = uf.user_field_id 
GROUP BY ud.user_id;

好的，根据您的新要求，一个简单的JOIN即可：

SELECT  ud.user_id,
        MIN(CASE WHEN uf.name = 'firstname' THEN ud.value END) as firstname,
        MIN(CASE WHEN uf.name = 'birthday' THEN ud.value END) as birthday,
        MIN(ac.status) as status
FROM user_data ud
INNER JOIN user_fields uf
    ON ud.user_field_id = uf.user_field_id 
LEFT JOIN api_calls ac
    ON ud.user_id = ac.user_id
GROUP BY ud.user_id;

Answer 2

您可以尝试将表格连接到自身并过滤仅使用生日值加入名称：

SELECT name.user_id, name.value AS Name, bday.value AS birthdate
FROM t name
INNER JOIN t bday
ON name.user_id = bday.user_id
AND name.t = 3 AND bday.t = 2

SQL选择包含多个行的一个ID

2 个答案: