Snowflake 中的数据操作
Jake Roach
Field Data Engineer
评估某字段的值，并基于该值执行操作。
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CASE 语句
CASE
CASE ... WHEN ... THEN ... END
WHEN
THEN
END
SELECT student_name, CASE WHEN grade_num = 12 THEN 'Senior' WHEN grade_num = 11 THEN 'Junior' ... END AS grade FROM students;
| student_name | grade | | --------------- | --------- | | Viraj | Junior | | Stephanie | Senior |
SELECT student_id, course_name, CASE WHEN grade = 'A' THEN 4.0 WHEN grade = 'B' THEN 3.0 WHEN grade = 'C' THEN 2.0 WHEN grade = 'D' THEN 1.0 WHEN grade = 'F' THEN 0.0 END AS gpa -- 平均绩点（GPA） FROM student_courses;
SELECT student_id, course_name,
WHEN grade = 'A' THEN 4.0
WHEN grade = 'B' THEN 3.0
WHEN grade = 'C' THEN 2.0 WHEN grade = 'D' THEN 1.0 WHEN grade = 'F' THEN 0.0
END AS gpa -- 平均绩点（GPA）
FROM student_courses;
| student_id | course_name | gpa | | ---------- | ------------- | --- | | 001 | Stats 101 | 4.0 | | 001 | Calculus | 3.0 | | 002 | Biology | 3.0 | | 003 | Finance | 1.0 | | 004 | Engineering | 4.0 | | 004 | Sales | 2.0 | | 004 | Botany | 4.0 | ...
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