SQLite 中的“如果、那么、否则”

使用SQLite中的"如果、那么、否则"语句实现条件逻辑

sql
SELECT
    column1,
    column2,
    CASE
        WHEN condition1 THEN result1
        WHEN condition2 THEN result2
        ELSE result3
    END AS new_column
FROM
    your_table;

sql
SELECT
    student_name,
    score,
    CASE
        WHEN score >= 90 THEN 'A'
        WHEN score >= 80 AND score < 90 THEN 'B'
        WHEN score >= 70 AND score < 80 THEN 'C'
        WHEN score >= 60 AND score < 70 THEN 'D'
        ELSE 'F'
    END AS grade
FROM
    student_scores;

sql
SELECT
    student_name,
    subject,
    score,
    CASE
        WHEN subject = 'Math' THEN
            CASE
                WHEN score >= 90 THEN score + 5
                ELSE score
            END
        ELSE score
    END AS final_score
FROM
    student_scores;