[英]Return multiple counts with single PL SQL Query
我有以下两个返回计数的PL / SQL Oracle查询:
SELECT count(*)
INTO counter_for_x
FROM Table_Name
WHERE Column_Name = 'X';
SELECT count(*)
INTO counter_for_y
FROM Table_Name
WHERE Column_Name = 'Y';
是否可以编写一个返回计数并填充相应计数器变量的查询?
SELECT (
SELECT COUNT(*)
FROM table_name
WHERE column_name = 'X'
),
(
SELECT COUNT(*)
FROM table_name
WHERE column_name = 'Y'
)
INTO counter_for_x, counter_for_y
FROM dual
你可以,但我不会这样做......
select nvl(sum(decode(column_name,'X',1,0)),0), nvl(sum(decode(column_name,'Y',1,0)),0)
into counter_for_x, counter_for_y
from table_name
where column_name in ('X', 'Y');
其他方式。
SELECT
Max(CASE WHEN Column_Name = 'X' THEN Count ELSE NULL END) AS Count_X ,
MAX(CASE WHEN Column_Name = 'Y' THEN Count ELSE NULL END) AS Count_Y
FROM
(
SELECT count(*) as Count, Column_Name
FROM Table_Name
Where Column_Name in ('X', 'Y')
Group By Column_Name
) AS InnerTable
这样做:
select count(decode(column_name,'X',1)) x_count
, count(decode(column_name,'Y',1)) y_count
into counter_for_x, counter_for_y
from table_name
where column_name in ('X','Y');
或者如果您更喜欢使用CASE:
select count(case when column_name = 'X' then 1 end) x_count
, count(case when column_name = 'Y' then 1 end) y_count
into counter_for_x, counter_for_y
from table_name
where column_name in ('X','Y');
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