如何一定數量的在SQL Server索引

Question

如何找到一定數量的index給定值

例如，如果我的號碼是1001

我既需要一個目前的指數在1001 即， 1和4

我使用charindex但隨着這個我就能得到的只有charindex的第一1。

Answer 1

Declare @String VARCHAR(10) = '1001' 

SELECT CHARINDEX('1', @String) AS FirstOne 
     ,CHARINDEX('1', @String, CHARINDEX('1', @String)+1) NextOne 

結果

FirstOne NextOne 
    1   4 

CHARINDEX有一個可選的第三個參數[開始索引]

CHARINDEX (expressionToFind ,expressionToSearch [ , start_location ]) 

或者你可以做這樣的事情....

Declare @String VARCHAR(10) = '110101' 


DECLARE @Table TABLE ([Char] CHAR(1), [INDEX] INT)  
DECLARE @ChartoSearch CHAR(1) = '1'  
DECLARE @i INT = 0  

WHILE (LEN(@String) >= @i) 
BEGIN 
    INSERT INTO @Table ([Char], [INDEX]) 
    SELECT @ChartoSearch,CHARINDEX(@ChartoSearch, @String, @i) 
    SET @i = @i + 1; 
END 

SELECT DISTINCT * FROM @Table 

結果集

╔══════╦═══════╗ 
║ Char ║ INDEX ║ 
╠══════╬═══════╣ 
║ 1 ║  1 ║ 
║ 1 ║  2 ║ 
║ 1 ║  4 ║ 
║ 1 ║  6 ║ 
╚══════╩═══════╝ 

Answer 2

如果人數只有4位數，那麼我建議一個明確case聲明：

select (case when number = '0000' then 0 
      when number = '0001' then 1 
      when number = '0010' then 1 
      when number = '0011' then 2 
      when number = '0100' then 1 
      when number = '0101' then 2 
      when number = '0110' then 2 
      when number = '0111' then 3 
      when number = '1000' then 1 
      when number = '1001' then 2 
      when number = '1010' then 2 
      when number = '1011' then 3 
      when number = '1100' then 2 
      when number = '1101' then 3 
      when number = '1110' then 3 
      when number = '1111' then 4 
     end) as NumOnes 

或者說，這樣的計算：

select ((case when number like '1%' then 1 else 0 end) + 
     (case when number like '_1%' then 1 else 0 end) + 
     (case when number like '__1%' then 1 else 0 end) + 
     (case when number like '___1%' then 1 else 0 end) 
     ) as NumOnes 

您也可以將這些操作作爲號碼進行編號：

select ((case when number & 1 > 0 then 1 else 0 end) + 
     (case when number & 2 > 0 then 1 else 0 end) + 
     (case when number & 4 > 0 then 1 else 0 end) + 
     (case when number & 8 > 0 then 1 else 0 end) 
     ) as NumOnes