使用SQL REPLACE，其中被替换的字符串和替换是另一个替换的结果

Question

尝试替换我的数据库中的一些字符串，我有两个表。table_2上的替换使用第一次替换的结果作为输入：

当前状态(字符串只是一个替身，它可以是任何东西，重要的部分是破折号)：

|table_1 - col1|    |table_2   - col1            |       
----------------    ------------------------------
|string-1      |    |text string-1 text string-3 |     
|string-2      |    |text string-3 string-2 t-ext|
|string-3      |    |string-2 text string-3 te-xt|

期望的结果：

|table_1 - col1 |    |table_2 - col1              |       
-----------------    ------------------------------
|string_1       |    |text string_1 text string_3 |     
|string_2       |    |text string_3 string_2 t-ext|
|string_3       |    |string_2 text string_3 te-xt|

简单地说，我想在table_1中用_替换-，并在table_2上执行相应的替换。

我想出了第一部分，但我想不出table_2上的替换部分：

SELECT col1, REPLACE(col1, '-', '_') as Replacement  
FROM table_1 
where col1 like '%-%'

我需要这样做(这段代码不正确)：

SELECT REPLACE(col1, 
    SELECT [col1] FROM [table_1] where col1 like '%-%',
    SELECT REPLACE([col1], '-', '_') FROM [table_1] where col1 like '%-%')      
from table_2

Answer 1

不超过2次更换

SELECT t2.col2, REPLACE(REPLACE(t2.col2,t1.col1,REPLACE(t1.col1, '-', '_')),t3.col1,REPLACE(t3.col1, '-', '_')) 
FROM table_2 t2
JOIN table_1 t1 ON t2.col2 like '%' +t1.col1+'%' AND t1.col1 LIKE '%-%'
LEFT JOIN table_1 t3 ON t3.col1 <> t1.col1 AND t2.col2 LIKE '%'+t3.col1+'%' AND t3.col1 LIKE '%-%'
WHERE t2.col2 LIKE '%-%'

Answer 2

这是完全即席的，不需要递归：

DECLARE @table_1 TABLE(ID INT IDENTITY,col1 VARCHAR(100));
INSERT INTO @table_1 VALUES    
 ('string-1'),('string-2'),('string-3');

DECLARE @table_2 TABLE(ID INT IDENTITY,col1 VARCHAR(100));
INSERT INTO @table_2 VALUES    
 ('text string-1 text string-3'),('text string-3 string-2 t-ext'),('string-2 text string-3 te-xt');

--第一个CTE替换t1中的值

WITH t1New AS
(
    SELECT ID AS t1_ID
          ,t1.col1 AS t1c1
          ,REPLACE(t1.col1,'-','_') AS new_t1c1 
    FROM @table_1 AS t1
)

--第二个CTE在空格上拆分t2字符串

,t2Splitted AS
(
    SELECT ID
          ,col1 AS t2c1
          ,CAST('<x>' + REPLACE(t2.col1,' ','</x><x>') + '</x>' AS XML) AS Casted
    FROM @table_2 AS t2
)

--此CTE将值映射到拆分的部分

,Mapped AS
(
    SELECT t1New.*
          ,t2Splitted.ID AS t2_ID 
          ,ROW_NUMBER() OVER(PARTITION BY t2Splitted.ID ORDER BY (SELECT NULL)) AS PartIndex
          ,part.value('.','nvarchar(max)') AS Part
    FROM t2Splitted
    CROSS APPLY t2Splitted.Casted.nodes('/x') AS A(part)
    LEFT JOIN t1New ON t1New.t1c1=part.value('.','nvarchar(max)')
)

--如果存在映射，则采用新值，否则采用旧值

,NewValues AS
(
    SELECT *
           ,CASE WHEN t1c1 IS NOT NULL THEN new_t1c1 ELSE Part END AS newValue
    FROM Mapped 
)

--最终的CTE将字符串与原始顺序中的空格重新连接

,Final AS
(
    SELECT nv1.t2_ID
      ,(SELECT ' ' + nv2.newValue
        FROM NewValues AS nv2
        WHERE nv2.t2_ID=nv1.t2_ID
        ORDER BY PartIndex
        FOR XML PATH('')) AS FinalValue
    FROM NewValues AS nv1
    GROUP BY nv1.t2_ID
)

--最后一个值用于更新原始表

UPDATE t2 SET t2.col1=Final.FinalValue
FROM @table_2 AS t2
INNER JOIN Final ON Final.t2_ID=t2.ID

怎么了:更新t1，这是一行代码，去掉FinalValue中的尾随空格:-)

SELECT * FROM @table_2

Answer 3

基于变量的替换可以通过替换一个表来完成。

DECLARE @Raw NVARCHAR(MAX) = '...';
SELECT @Raw= REPLACE(@Raw, P, R)
FROM (VALUES ('string-1', 'string_1'),
            ('string-2','string_2'),
            ('string-3','string_3'),
            ('string-4','string_4'),
) AS T(P, R);

要对表执行相同的逻辑，请考虑一些语句，例如

SELECT col1, MultipleReplace(col1, replacement_table(P, R))
FROM some_table

因此，创建一个接受字符串输入和替换表的函数。为了将表传递给函数，我们必须创建一个表类型。

CREATE TYPE dbo.MulReplacements AS TABLE 
(
    Pattern NVARCHAR(MAX) NOT NULL,
    Replacement NVARCHAR(MAX) NOT NULL
)

那么这个函数就是

CREATE FUNCTION dbo.MulReplace(
    @string AS NVARCHAR(MAX),
    @replacements AS dbo.MulReplacements READONLY
)
RETURNS NVARCHAR(MAX)
AS
BEGIN
    DECLARE @result AS NVARCHAR(MAX) = @string;

    SELECT @result = REPLACE(@result, R.Pattern, R.Replacement) 
    FROM @replacements AS R;

    RETURN @result;
END

把所有东西放在一起

DECLARE @replacement AS dbo.MulReplacements;

INSERT INTO @replacement
SELECT col1, REPLACE(col1, '-', '_')
FROM (VALUES ('string-1'), ('string-2'), ('string-3')) AS table_1(col1)

SELECT col1, dbo.Mulreplace(col1, @replacement)
FROM (VALUES ('text string-1 text string-3'), ('text string-3 string-2 t-ext'), ('string-2 text string-3 te-xt')) AS table_2(col1)