从所有行的表字段中查找唯一字符

Question

如何查找具有多行的字段中使用的不同字符的数量。

例如，如果有两行有像abcd和eaafg*这样的数据，则使用的不同字符是abcdefg*。

Answer 1

尝试这一个 -

INSERT INTO @temp (txt) 
VALUES ('abcd3'), ('abcdefg*') 

SELECT disword = (
SELECT DISTINCT dt.ch 
FROM (
SELECT ch = SUBSTRING(t.mtxt, n.number + 1, 1) 
FROM [master].dbo.spt_values n 
CROSS JOIN (
    SELECT mtxt = (
    SELECT txt 
    FROM @temp 
    FOR XML PATH(N''), TYPE, ROOT).value(N'root[1]', N'NVARCHAR(MAX)' 
) 
) t 
WHERE [type] = N'p' 
    AND number <= LEN(mtxt) - 1 
) dt 
FOR XML PATH(N''), TYPE, ROOT).value(N'root[1]', N'NVARCHAR(MAX)' 
) 

---

实施例（编辑）：

SET NOCOUNT ON; 

DECLARE @temp TABLE (txt VARCHAR(8000)) 

INSERT INTO @temp (txt) 
VALUES ('abcd'), ('abcdefg*'), (REPLICATE('-', 8000)), (REPLICATE('+', 8000)) 

DECLARE @t TABLE (i BIGINT) 

DECLARE 
     @i BIGINT = 1 
    , @l BIGINT = (
     SELECT SUM(LEN(txt)) 
     FROM @temp 
    ) 

WHILE (@i <= @l) BEGIN 

    INSERT INTO @t (i) 
    VALUES (@i), (@i+1), (@i+2), (@i+3), (@i+4), (@i+5), (@i+6), (@i+7), (@i+8), (@i+9) 
    SELECT @i += 10 

END 

SELECT disword = (
    SELECT DISTINCT dt.ch 
    FROM (
     SELECT ch = SUBSTRING(t.mtxt, n.i, 1) 
     FROM @t n 
     CROSS JOIN (
      SELECT mtxt = (
       SELECT txt 
       FROM @temp 
       FOR XML PATH(N''), TYPE, ROOT).value(N'root[1]', N'NVARCHAR(MAX)' 
      ) 
     ) t 
    ) dt 
    FOR XML PATH(N''), TYPE, ROOT).value(N'root[1]', N'NVARCHAR(MAX)' 
) 

---

看看叔此溶液 -

SELECT 
     dt.ch 
    , cnt = COUNT(1) 
FROM (
    SELECT ch = SUBSTRING(t.mtxt, n.i, 1) 
    FROM @t n 
    CROSS JOIN (
     SELECT mtxt = (
      SELECT txt 
      FROM @temp 
      FOR XML PATH(N''), TYPE, ROOT).value(N'root[1]', N'NVARCHAR(MAX)') 
    ) t 
) dt 
WHERE dt.ch != '' 
GROUP BY dt.ch 
ORDER BY cnt DESC 

Answer 2

下面是可参考的问题你问：

How do I get distinct characters of string column in mssql?

和

SQL: how to get all the distinct characters in a column, across all rows

Answer 3

随着tallys：

DECLARE @t TABLE (s NVARCHAR(MAX)) 

INSERT INTO @t 
VALUES ('abcd'), ('abcdefg*') 

;WITH tally AS(SELECT ROW_NUMBER() OVER(ORDER BY (SELECT 1)) i 
FROM (VALUES(0),(0),(0),(0),(0),(0),(0),(0),(0),(0)) t1(n) 
CROSS JOIN (VALUES(0),(0),(0),(0),(0),(0),(0),(0),(0),(0)) t2(n)) 

SELECT 
(  SELECT DISTINCT sb 
     FROM tally 
     CROSS APPLY (SELECT SUBSTRING(s, i, 1) sb FROM @t) ca 
     WHERE sb <> '' 
FOR  XML PATH(N'') , TYPE , ROOT).value(N'root[1]', N'NVARCHAR(MAX)')