SELECT 学号,
SUM(CASE 考试科目号 WHEN 1 THEN 成绩 ELSE 0 END) AS 科目1成绩,
SUM(CASE 考试科目号 WHEN 2 THEN 成绩 ELSE 0 END) AS 科目2成绩,
SUM(CASE 考试科目号 WHEN 3 THEN 成绩 ELSE 0 END) AS 科目3成绩
FROM tablename
SUM(CASE 考试科目号 WHEN 1 THEN 成绩 ELSE 0 END) AS 科目1成绩,
SUM(CASE 考试科目号 WHEN 2 THEN 成绩 ELSE 0 END) AS 科目2成绩,
SUM(CASE 考试科目号 WHEN 3 THEN 成绩 ELSE 0 END) AS 科目3成绩
FROM tablename
SUM(CASE 考试科目号 WHEN 1 THEN 成绩 ELSE 0 END) AS 科目1成绩,
SUM(CASE 考试科目号 WHEN 2 THEN 成绩 ELSE 0 END) AS 科目2成绩,
SUM(CASE 考试科目号 WHEN 3 THEN 成绩 ELSE 0 END) AS 科目3成绩
FROM tablename
GROUP BY 学号