Oracle函数之LISTAGG

最近在学习的过程中，发现一个挺有意思的Oracle函数，它可实现对列值的拼接。下面我们来看看其具体用法。用法：对其作用，官方文档的解释如下：For a specified measure, LISTAGG orders data within each group specified in the ORDER BY clause and then concatenates the values of the measure column.即在每个分组内，LISTAGG根据order by子句对列植进行排序，将排序后的结果拼接起来。measure_expr：可以是任何基于列的表达式。delimiter：分隔符，默认为NULorder_by_clause：order by子句决定了列值被拼接的顺序。通过该用法，可以看出LISTAGG函数不仅可作为一个普通函数使用，也可作为分析函数。order_by_clause和query_partition_clause的用法如下：下面对该函数进行举例说明：普通函数，对工资进行排序，用逗号进行拼接。SQL> select listagg（ename,","）within group（order by sal）name from emp;NAME----------------------------------------------------------------------------------------------------SMITH,JAMES,ADAMS,MARTIN,WARD,MILLER,TURNER,ALLEN,CLARK,BLAKE,JONES,FORD,SCOTT,KING分组函数：SQL> select deptno,listagg（ename,","）within group（order by sal）name from emp group by deptno;DEPTNO NAME---------- ----------------------------------------------------------------------------------------------------10 MILLER,CLARK,KING20 SMITH,ADAMS,JONES,FORD,SCOTT30 JAMES,MARTIN,WARD,TURNER,ALLEN,BLAKE分析函数：SQL> select deptno,ename,sal,listagg（ename,","）within group（order by sal）over（partition by deptno）name from emp;DEPTNO ENAME SAL NAME---------- ---------- ---------- ----------------------------------------10 MILLER 1300 MILLER,CLARK,KING10 CLARK2450 MILLER,CLARK,KING10 KING 5000 MILLER,CLARK,KING20 SMITH 800 SMITH,ADAMS,JONES,SCOTT,FORD20 ADAMS1100 SMITH,ADAMS,JONES,SCOTT,FORD20 JONES2975 SMITH,ADAMS,JONES,SCOTT,FORD20 SCOTT3000 SMITH,ADAMS,JONES,SCOTT,FORD20 FORD 3000 SMITH,ADAMS,JONES,SCOTT,FORD30 JAMES 950 JAMES,MARTIN,WARD,TURNER,ALLEN,BLAKE30 MARTIN 1250 JAMES,MARTIN,WARD,TURNER,ALLEN,BLAKE30 WARD 1250 JAMES,MARTIN,WARD,TURNER,ALLEN,BLAKE30 TURNER 1500 JAMES,MARTIN,WARD,TURNER,ALLEN,BLAKE30 ALLEN1600 JAMES,MARTIN,WARD,TURNER,ALLEN,BLAKE30 BLAKE2850 JAMES,MARTIN,WARD,TURNER,ALLEN,BLAKE14 rows selected.更多Oracle相关信息见Oracle 专题页面 http://www.linuxidc.com/topicnews.aspx？tid=12本文永久更新链接地址