在存储逗号分隔值的列值中搜索值 [英] Search a value in the column value that stores comma separated values
问题描述
假设我有一个表 XYZ,其中有一列 Weekend_Days 存储值,SUNDAY,SATURDAY,我有另一个表 ABC,其日期 ACT_DATE 可以是任何日期.现在我必须检查这个日期是否是周末.
Suppose I have table XYZ with a column Weekend_Days which stores the value, SUNDAY,SATURDAY and I have another table ABC with a date, ACT_DATE which can be any date. Now I have to check if the day on this date is a weekend or not.
我尝试使用:
select ACT_DATE
, case
when UPPER(TO_CHAR(ACT_DATE,'DAY')) IN (SELECT Weekend_Days from XYZ)
then 1
else 0
end as Weekend_Flag
from ABC
但它不起作用,它只是为所有日期返回 0.
But it is not working, its just returning 0 for all dates.
尝试将 Weekend_Days 的值存储为 ('SUNDAY','SATURDAY') 但没有用.
Tried storing the value of Weekend_Days as ('SUNDAY','SATURDAY') but it didn't work.
样本数据:
表格 XYZ:
WEEKEND_DAYS
---------------
SUNDAY,SATURDAY
表格 ABC:
ACT_DATE
---------
02-Feb-16
06-Feb-16
当前结果:
ACT_DATE WEEKEND_FLAG
--------- ------------
02-Feb-16 0
06-Feb-16 0
预期结果:
ACT_DATE WEEKEND_FLAG
--------- ------------
02-Feb-16 0
06-Feb-16 1
推荐答案
Oracle 设置:
CREATE OR REPLACE FUNCTION split_String(
i_str IN VARCHAR2,
i_delim IN VARCHAR2 DEFAULT ','
) RETURN SYS.ODCIVARCHAR2LIST DETERMINISTIC
AS
p_result SYS.ODCIVARCHAR2LIST := SYS.ODCIVARCHAR2LIST();
p_start NUMBER(5) := 1;
p_end NUMBER(5);
c_len CONSTANT NUMBER(5) := LENGTH( i_str );
c_ld CONSTANT NUMBER(5) := LENGTH( i_delim );
BEGIN
IF c_len > 0 THEN
p_end := INSTR( i_str, i_delim, p_start );
WHILE p_end > 0 LOOP
p_result.EXTEND;
p_result( p_result.COUNT ) := SUBSTR( i_str, p_start, p_end - p_start );
p_start := p_end + c_ld;
p_end := INSTR( i_str, i_delim, p_start );
END LOOP;
IF p_start <= c_len + 1 THEN
p_result.EXTEND;
p_result( p_result.COUNT ) := SUBSTR( i_str, p_start, c_len - p_start + 1 );
END IF;
END IF;
RETURN p_result;
END;
/
CREATE TABLE xyz ( weekend_days ) AS
SELECT 'SATURDAY,SUNDAY' FROM DUAL;
CREATE TABLE abc ( act_date ) AS
SELECT DATE '2016-02-02' FROM DUAL UNION ALL
SELECT DATE '2016-02-06' FROM DUAL;
查询
SELECT act_date,
CASE WHEN w.Weekend_day IS NULL THEN 0 ELSE 1 END AS weekend_flag
FROM abc a
LEFT OUTER JOIN
( SELECT t.column_value AS weekend_day
FROM xyz x,
TABLE( split_String( x.weekend_days ) ) t
) w
ON TRIM( TO_CHAR( a.ACT_DATE, 'DAY' ) ) = w.Weekend_day;
输出:
ACT_DATE WEEKEND_FLAG
--------- ------------
06-FEB-16 1
02-FEB-16 0
替代查询:
SELECT act_date,
CASE
WHEN INSTR( x.weekend_days, TRIM( TO_CHAR( act_date, 'DAY' ) ) ) > 0
THEN 1
ELSE 0
END AS weekend_flag
FROM abc a
CROSS JOIN
xyz x;
这将提供相同的输出并且适用于日期名称,但不适用于一般情况,因为您可能会得到与子字符串的误报匹配.
This will give the same output and will work for names of days but will not work for a general case as you might get a false positive match to a sub-string.
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