无法使用 mysql 7 中的复杂检查约束案例验证数据答案

【问题标题】：Cannot validate data using complex check constraint case in mysql 7无法使用 mysql 7 中的复杂检查约束案例验证数据
【发布时间】：2021-11-12 18:31:36
【问题描述】：

ALTER TABLE
    src_branches ADD CONSTRAINT bmod_to_id_check(
        CASE WHEN bmod 7 THEN CASE WHEN id BETWEEN 0 AND 2 THEN 1 ELSE 0
        CASE WHEN bmod 6 THEN CASE WHEN id BETWEEN 600 AND 699 THEN 1 ELSE 0
        CASE WHEN bmod 5 THEN CASE WHEN id BETWEEN 500 AND 599 THEN 1 ELSE 0
        CASE WHEN bmod 4 THEN CASE WHEN id BETWEEN 400 AND 499 THEN 1 ELSE 0
        CASE WHEN bmod 3 THEN CASE WHEN id BETWEEN 300 AND 499 THEN 1 ELSE 0
        CASE WHEN bmod 2 THEN CASE WHEN id BETWEEN 2 AND 300 THEN 1 ELSE 0
        CASE WHEN bmod 1 THEN CASE WHEN id BETWEEN 2 AND 300 THEN 1 ELSE 0
    END ELSE 1
END = 1
);

// 我的目标是当 bmod = some integer 时将我的 id 保持在一个设定的范围内 // 我对替代品持开放态度

【问题讨论】：

标签： validation mariadb constraints case

【解决方案1】：

注意CASE运算符的语法：

ALTER TABLE
    src_branches ADD CONSTRAINT bmod_to_id check(
    case bmod when 7 then id BETWEEN 0 AND 2
    when 6 then id BETWEEN 600 AND 699
    when 5 then id BETWEEN 500 AND 599
    when 4 then id BETWEEN 400 AND 499
    when 3 then id BETWEEN 300 AND 499
    when 2 then id BETWEEN 2 AND 300
    when 1 then id BETWEEN 2 AND 300
    else 0
    end)

所以id BETWEEN x AND y 是一个为真 (1) 或假 (0) 的表达式。

也要注意constraint syntax。

参考：fiddle

【讨论】：