本文介绍了oracle中有没有类似mysql中group_concat的功能?的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
My inputs are in this way.
col1 col2
1 a
1 b
2 c
2 d
2 e
O/p: Should Be like
col1 col2
1 a,b
2 c,d,e
I want a query that can be fired at DB level. I've tried various ways, but wasn't able to make this out...
解决方案
11g and higher: Use listagg:
SELECT
col1,
LISTAGG(col2, ', ') WITHIN GROUP (ORDER BY col2) "names"
FROM table_x
GROUP BY col1
10g and lower: One method is to use a function:
CREATE OR REPLACE FUNCTION get_comma_separated_value (input_val in number)
RETURN VARCHAR2
IS
return_text VARCHAR2(10000) := NULL;
BEGIN
FOR x IN (SELECT col2 FROM table_name WHERE col1 = input_val) LOOP
return_text := return_text || ',' || x.col2 ;
END LOOP;
RETURN LTRIM(return_text, ',');
END;
/
To use the function:
select col1, get_comma_separated_value(col1) from table_name
Note: There is an (unsupported) function WM_CONCAT available on certain older versions of Oracle, which might help you out - see here for details.
In MySQL:
SELECT col1, GROUP_CONCAT(col2) FROM table_name GROUP BY col1
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