我从表中提取信息有点复杂。我不确定什么是最好的方法。
我正在列出表格示例:
I need information just for Dept and Class for each student
Can we construct the table like this?
您可以加入两个表,然后按学生进行汇总,使用枢轴逻辑得出所需的属性:
SELECT
s.id,
s.name,
MAX(CASE WHEN si.property = 'dept' THEN si.value END) AS dept,
MAX(CASE WHEN si.property = 'class' THEN si.value END) AS class
FROM student s
LEFT JOIN student_information si
ON s.id = si.student_id
GROUP BY
s.id,
s.name;