只在sql上選擇數字值

Question

我知道那裏已經有一些相同的問題了，但是這個問題讓我很困惑。

我有這個疑問：

SELECT 
    CASE 
    WHEN COALESCE(substring(location_name FROM '[0-9]+'), location_name) != '' 
    THEN COALESCE(substring(location_name FROM '[0-9]+'), location_name) 
    ELSE '1' 
END AS sequence 
FROM LOCATION 

我想從查詢得到的是：

1. 如果location_name不包含任何數值，然後返回1
2. 如果location_name包含數字值，則只獲取最後一個數值（在字符串後），即 即c2傳送帶10應僅返回10
3. 如果location_name只包含數值，然後返回1

但我得到的是這樣的：

location_name expected result  what I get 
            using [0-9]   using [0-9]+ 
carousel 1  1     1     1 
carousel 2  2     2     2 
carousel 3  3     3     3 
carousel 12  12     1     12 
bottom banner 1     bottom banner  bottom banner 
c2 carousel 1 1     2     2 
c2 carousel 3 3     2     2 
59977   1     5     59977 

是否有可能做到這一點的SQL？

Answer 1

試試這個：（我認爲這將返回預期的結果，否則記你會得到什麼。）

SELECT location_name, 
CASE WHEN concat('',location_name * 1) = location_name THEN 
    1 
WHEN concat('',reverse(substring_index(reverse(location_name), ' ', 1)) * 1) = reverse(substring_index(reverse(location_name), ' ', 1)) THEN 
    reverse(substring_index(reverse(location_name), ' ', 1)) 
ELSE 
    1 
END AS EXPECTED_RESULT 
FROM YourTable 

--Quick Demo here:MySQL

這是不好的，當你突然變更後的標籤MySQL來PGSQL。我所有的作品都浪費了。

這裏是PGSQL代碼：

創建一個函數來檢查ISDIGIT（）：

create function isdigits(text) returns boolean as ' 
select $1 ~ ''^(-)?[0-9]+$'' as result 
' language sql; 

然後這裏是代碼：

SELECT location_name, 
     CASE WHEN isdigits(location_name) = true THEN 1 
      WHEN isdigits(substr(location_name, length(regexp_replace(location_name, '\\s\\S+$', '')) + 2)) = true THEN 
       substr(location_name, length(regexp_replace(location_name, '\\s\\S+$', '')) + 2)::int 
      ELSE 1 
     END AS Result 
    FROM YourTable 

--Quick Demo - PGSQL.

Answer 2

-- Create one function first which will help to check wether value is numeric or not 

CREATE FUNCTION mysql_IsNumeric(val TEXT) RETURNS int(11) 
RETURN val REGEXP '^(-|\\+){0,1}([0-9]+\\.[0-9]*|[0-9]*\\.[0-9]+|[0-9]+)$'; 

--create function that return numeric values only  
CREATE FUNCTION mysql_NumericOnly(val TEXT) RETURNS text CHARSET latin1 
BEGIN 
DECLARE idx INT DEFAULT 0; 
IF mysql_IsNumeric(val) = 0 THEN 
IF ISNULL(val) THEN RETURN NULL; END IF; 
IF LENGTH(val) = 0 THEN RETURN ""; END IF; 
SET idx = LENGTH(val); 
WHILE idx > 0 DO 
IF strcmp(SUBSTRING(val,idx,1),'.')!=0 and mysql_IsNumeric(SUBSTRING(val,idx,1)) = 0 THEN 
SET val = REPLACE(val,SUBSTRING(val,idx,1),""); 
SET idx = LENGTH(val)+1; 
END IF; 
SET idx = idx - 1; 
END WHILE; 
END IF; 
RETURN val; 
END; 


select *, 
case when mysql_IsNumeric(location_name)=1 then 1 
case when location_name!=mysql_NumericOnly(location_name) THEN 
mysql_NumericOnly(Reverse(Left(REVERSE(location_name),INSTR(REVERSE(location_name),' '))) 
    else 1 end as reselut  
    from YourTable