如何实现mysql逗号隔开的数据去重

流程图

flowchart TD
    A[获取逗号隔开的数据] --> B[拆分数据]
    B --> C[去重]
    C --> D[合并数据]
    D --> E[更新原数据]

表格展示步骤

步骤 描述
1 获取逗号隔开的数据
2 拆分数据
3 去重
4 合并数据
5 更新原数据

每一步操作及代码

步骤1：获取逗号隔开的数据

-- 选取需要去重的数据字段
SELECT data_column FROM table_name;

步骤2：拆分数据

-- 将逗号隔开的数据拆分成行
SELECT 
    SUBSTRING_INDEX(SUBSTRING_INDEX(data_column, ',', n), ',', -1) AS data
FROM
    table_name
    JOIN (SELECT 1 n UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4) num
    ON CHAR_LENGTH(data_column)
       -CHAR_LENGTH(REPLACE(data_column, ',', '')) 
       >= n-1;

步骤3：去重

-- 使用DISTINCT去重
SELECT DISTINCT data FROM (
    SELECT 
        SUBSTRING_INDEX(SUBSTRING_INDEX(data_column, ',', n), ',', -1) AS data
    FROM
        table_name
        JOIN (SELECT 1 n UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4) num
        ON CHAR_LENGTH(data_column)
            -CHAR_LENGTH(REPLACE(data_column, ',', '')) 
            >= n-1
) AS sub_query;

步骤4：合并数据

-- 使用GROUP_CONCAT合并数据
SELECT GROUP_CONCAT(data) AS deduped_data
FROM (
    SELECT DISTINCT data FROM (
        SELECT 
            SUBSTRING_INDEX(SUBSTRING_INDEX(data_column, ',', n), ',', -1) AS data
        FROM
            table_name
            JOIN (SELECT 1 n UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4) num
            ON CHAR_LENGTH(data_column)
                -CHAR_LENGTH(REPLACE(data_column, ',', '')) 
                >= n-1
    ) AS sub_query
) AS final_query;

步骤5：更新原数据

-- 更新原数据字段为去重后的数据
UPDATE table_name
SET data_column = (
    SELECT GROUP_CONCAT(data) AS deduped_data
    FROM (
        SELECT DISTINCT data FROM (
            SELECT 
                SUBSTRING_INDEX(SUBSTRING_INDEX(data_column, ',', n), ',', -1) AS data
            FROM
                table_name
                JOIN (SELECT 1 n UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4) num
                ON CHAR_LENGTH(data_column)
                    -CHAR_LENGTH(REPLACE(data_column, ',', '')) 
                    >= n-1
        ) AS sub_query
    ) AS final_query
);

关系图

erDiagram
    DATA_TABLE {
        varchar data_column
    }

以上步骤就是如何实现mysql逗号隔开的数据去重的完整流程。希望能帮助你解决这个问题。祝学习顺利！