oracle函数listagg使用

oracle函数listagg使用

作用
可以实现将多列记录聚合为一列记录，实现数据的压缩

语法结构
listagg(measure_expr，delimiter) within group ( order by order_by_clause);

解释：measure_expr可以是基于任何列的表达式

delimiter分隔符，默认为NULL

order_by_clause决定了列值的拼接顺序

举例
普通函数，对工资进行排序，并按照逗号进行拼接

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,KING
20 SMITH,ADAMS,JONES,FORD,SCOTT
30 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,KING
    10 CLARK            2450 MILLER,CLARK,KING
    10 KING             5000 MILLER,CLARK,KING
    20 SMITH             800 SMITH,ADAMS,JONES,SCOTT,FORD
    20 ADAMS            1100 SMITH,ADAMS,JONES,SCOTT,FORD
    20 JONES            2975 SMITH,ADAMS,JONES,SCOTT,FORD
    20 SCOTT            3000 SMITH,ADAMS,JONES,SCOTT,FORD
    20 FORD             3000 SMITH,ADAMS,JONES,SCOTT,FORD
    30 JAMES             950 JAMES,MARTIN,WARD,TURNER,ALLEN,BLAKE
    30 MARTIN           1250 JAMES,MARTIN,WARD,TURNER,ALLEN,BLAKE
    30 WARD             1250 JAMES,MARTIN,WARD,TURNER,ALLEN,BLAKE
    30 TURNER           1500 JAMES,MARTIN,WARD,TURNER,ALLEN,BLAKE
    30 ALLEN            1600 JAMES,MARTIN,WARD,TURNER,ALLEN,BLAKE
    30 BLAKE            2850 JAMES,MARTIN,WARD,TURNER,ALLEN,BLAKE

14 rows selected.