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  • ora-01489 字符串连接的结果过长 解决方案

      如下代码,使用listagg进行分组拼接时,常常会报 ora-01489 错误,造成该报错的主要原因是:oracle对字符变量的长度限制,正常情况下,oracle定义的varchar2类型变量的长度不应超过4000字节,如有必要可转换为long 或clob类型。

      我之前遇到一次该报错,后来检查了下,是因为重复数据造成的,所以建议大家使用下面方法之前最好还是先看下数据。本文提供的所有方法总结于 ora-01489错误解决方案

    create table lu_meseno_temp as 
    select
        MDSENO,
        LISTAGG(to_char(MECODE), ',') WITHIN GROUP(ORDER BY MECODE) AS pjMECODE
    from
        lu_yb_sbda_md_temp
    group by
        MDSENO
    

      解决方案:

      方法一:自定义连接函数

    -- 定义 tab_varchar2  数据类型
    CREATE TYPE tab_varchar2 AS TABLE OF VARCHAR2(4000);
    
    -- 新建 concat_array 函数
    CREATE OR REPLACE FUNCTION concat_array(p tab_varchar2) RETURN CLOB IS
        l_result CLOB;
        BEGIN
            FOR cc IN (SELECT column_value FROM TABLE(p) ORDER BY column_value) LOOP
                l_result := l_result ||' '|| cc.column_value;
            END LOOP;
            return l_result;
        END;
    
    -- 分组拼接
    SELECT 
        item,
        concat_array(CAST(COLLECT(attribute) AS tab_varchar2)) attributes
    FROM 
        tb
    GROUP BY
        item;
    

      如果希望对上述结果进行排序,可以嵌套一层 order by 前4000字符。

    SELECT
    	*
    FROM 
    (
        SELECT 
            item,
            concat_array(CAST(collect(attribute) AS tab_varchar2)) attributes
        FROM
            tb
        GROUP BY
            item
    ) 
    order by 
        -- 表示截取长度4000,起始位置1
        dbms_lob.substr(attributes, 4000, 1);
    

      

    方法二:

    with 
        ItemAttribute  as (
            select
                'name'||level name,
                mod(level,3) itemid
            from dual
            connect by level < 2000
        ),
        ItemAttributeGrouped as (
            select
                xmlagg(xmlparse(content name||' ' wellformed) order by name).getclobval() attributes,
                itemid
            from ItemAttribute
            group by itemid
        )
    
    select 
        itemid,
        attributes,
        dbms_lob.substr(attributes,4000,1) sortkey
    from ItemAttributeGrouped
    order by dbms_lob.substr(attributes,4000,1);  
    

      文档 oracle listagg函数字符串链接的结果过长,给出的解决方案为:

    rtrim(xmlagg(XMLELEMENT(e, t.id, ',').EXTRACT('//text()')).getclobval(),',')
    

      其他方法:

    SELECT itemId, name
      FROM (
        SELECT itemId, name, min(dr) over (partition by itemId) as dr
          FROM (
            SELECT itemId, name,
                dense_rank() over (order by name, name1, name2, name3, name4) as dr
              FROM (
                SELECT Item.itemId,
                         Attribute.name,
                         LEAD(Attribute.name, 1)
                             OVER (PARTITION BY Item.itemId
                                 ORDER BY Attribute.name) AS name1,
                         LEAD(Attribute.name, 2)
                             OVER (PARTITION BY Item.itemId
                                 ORDER BY Attribute.name) AS name2,
                         LEAD(Attribute.name, 3)
                             OVER (PARTITION BY Item.itemId
                                 ORDER BY Attribute.name) AS name3,
                         LEAD(Attribute.name, 4)
                             OVER (PARTITION BY Item.itemId
                                 ORDER BY Attribute.name) AS name4
                    FROM Item
                    JOIN ItemAttribute
                      ON ItemAttribute.itemId = Item.itemId
                    JOIN Attribute
                      ON Attribute.attributeId = ItemAttribute.attributeId
                   )
              )
          )
    ORDER BY dr, name;
    

      

      

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  • 原文地址:https://www.cnblogs.com/iupoint/p/10974864.html
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