FIND_IN_SET(str, strlist)

SELECT FIND_IN_SET('B', 'A,B,C,D');   -- 返回 2
SELECT FIND_IN_SET('Z', 'A,B,C,D');   -- 返回 0
SELECT FIND_IN_SET(NULL, 'A,B,C,D');  -- 返回 NULL
SELECT FIND_IN_SET('B', NULL);        -- 返回 NULL
SELECT FIND_IN_SET('B', '');          -- 返回 0

-- 查詢所屬系統(tǒng)包含 '1' 的記錄
SELECT * FROM vehicle 
WHERE FIND_IN_SET('1', belonging_system) > 0;

-- 按用戶指定的順序排序（如 3,1,2）
SELECT * FROM user 
ORDER BY FIND_IN_SET(id, '3,1,2');

-- 如果參數(shù)為 NULL，查詢?nèi)?；否則按 IN 匹配
SELECT * FROM vehicle 
WHERE (?1 IS NULL OR FIND_IN_SET(?1, belonging_system) > 0);

-- 統(tǒng)計 VIN 中包含 'L58' 的記錄數(shù)
SELECT COUNT(*) FROM vehicle 
WHERE FIND_IN_SET('L58', vin) > 0;

-- 查詢 belonging_system 包含 systemId 的所有記錄
SELECT * FROM vehicle 
WHERE FIND_IN_SET('1', belonging_system) > 0;

-- 結(jié)合參數(shù)判空
SELECT * FROM vehicle 
WHERE (?1 IS NULL OR FIND_IN_SET(?1, belonging_system) > 0);

@Query(value = "SELECT * FROM vehicle v " +
       "WHERE (COALESCE(?1, NULL) IS NULL OR FIND_IN_SET(?1, v.belonging_system) > 0)", 
       nativeQuery = true)
Page<Vehicle> findBySystemId(@Param("systemId") String systemId, Pageable pageable);

-- 1. 基本查找
SELECT FIND_IN_SET('2', '1,2,3,4');  -- 返回 2

-- 2. 在 WHERE 中使用
SELECT * FROM user WHERE FIND_IN_SET('admin', roles) > 0;

-- 3. 結(jié)合 ORDER BY（按指定順序）
SELECT * FROM product 
WHERE id IN (3,1,2) 
ORDER BY FIND_IN_SET(id, '3,1,2');

-- 4. 結(jié)合 CASE
SELECT 
    name,
    CASE 
        WHEN FIND_IN_SET('admin', roles) > 0 THEN '管理員'
        WHEN FIND_IN_SET('user', roles) > 0 THEN '普通用戶'
        ELSE '未知'
    END AS role_name
FROM user;