Using SQL REPLACE where the replaced string and replacement are the result of another replacement - sql

Question

Trying to replace some strings on my database where I've got two tables. The replacement on table_2 uses the results of the first replacement as an input:
Current state (string is only a stand-in, it can be anything, the important part is the dash):
|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|
Desired Result:
|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|
Simply put I want to replace the - with _ in table_1 and also perform a corresponding replacement on table_2.
Came up with the first part, but I can't figure out the replacement part on table_2:
SELECT col1, REPLACE(col1, '-', '_') as Replacement
FROM table_1
where col1 like '%-%'
I need to do something like this (this code is INCORRECT):
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

For no more then 2 replacements
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

This is fully ad-hoc, no recursion needed:
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');
--The first CTE replaces the value in t1
WITH t1New AS
(
SELECT ID AS t1_ID
,t1.col1 AS t1c1
,REPLACE(t1.col1,'-','_') AS new_t1c1
FROM #table_1 AS t1
)
--The second CTE splits the strings of t2 on the blanks
,t2Splitted AS
(
SELECT ID
,col1 AS t2c1
,CAST('<x>' + REPLACE(t2.col1,' ','</x><x>') + '</x>' AS XML) AS Casted
FROM #table_2 AS t2
)
--This CTE maps the values to the splitted parts
,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)')
)
--If there is a mapping, the new value is taken, else take the old value
,NewValues AS
(
SELECT *
,CASE WHEN t1c1 IS NOT NULL THEN new_t1c1 ELSE Part END AS newValue
FROM Mapped
)
--The final CTE re-concatenates the string with blanks in the original order
,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
)
--This last value is used to update the original table
UPDATE t2 SET t2.col1=Final.FinalValue
FROM #table_2 AS t2
INNER JOIN Final ON Final.t2_ID=t2.ID
What's up to you: UPDATE t1, that's a one-liner and get rid of the trailing space in FinalValue :-)
SELECT * FROM #table_2

Answer 3

Variable based replacement can be done as replacing with a table.
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);
To execute the same logic against table, think about some statements like
SELECT col1, MultipleReplace(col1, replacement_table(P, R))
FROM some_table
So create a function that accepts a string input and a replacement table. In order to pass table to function, we have to create a table type.
CREATE TYPE dbo.MulReplacements AS TABLE
(
Pattern NVARCHAR(MAX) NOT NULL,
Replacement NVARCHAR(MAX) NOT NULL
)
Then the function would be
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
Put all together
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)

Answer 4

One way of doing it with Dynamic query. Replace the actual table name and column names (commented where to change).
DECLARE #colNames VARCHAR(MAX) = ''
SELECT #colNames = #colNames + ', [' + table1_Col1 + ']' FROM tableName1 -- Table1 Column and Table1 Name
DECLARE #ReqColNames VARCHAR(MAX) = STUFF(#colNames, 1, 1, '')
DECLARE #int int
SELECT #int = count(*) FROM tableName1 -- Table1 Name
DECLARE #replace varchar(max) = replicate('REPLACE(', #int) + 't2.table2_Col2' -- Table2 Column
DECLARE #replaceCols varchar(max) = ''
SELECT #replaceCols = #replaceCols + ', r.[' + table1_Col1 + '], replace(r.[' + table1_Col1 + '], ''-'', ''_''))' FROM tableName1 -- Table1 Column and Table1 Name
DECLARE #ReplaceString varchar(max) = #replace + #replaceCols
DECLARE #cmd varchar(max) = 'SELECT ' + #ReplaceString + ' FROM
(
SELECT * FROM tableName1
PIVOT
(MAX (table1_Col1) FOR table1_Col1 IN (' + #ReqColNames + ')) x
) r
CROSS JOIN tableName2 t2'
EXEC(#cmd)
Static Query: for above code (to show what the above dynamic code is generating):
Select replace(replace(replace(t2.table2_Col2
, r.[string-1], replace(r.[string-1], '-', '_'))
, r.[string-2], replace(r.[string-2], '-', '_'))
, r.[string-3], replace(r.[string-3], '-', '_'))
from
(
Select * from tableName1
PIVOT
(MAX (table1_Col1) FOR table1_Col1 IN ([string-1], [string-2], [string-3])) x
) r
CROSS JOIN tableName2 t2
Output:
text string_1 text string_3
text string_3 string_2 t-ext
string_2 text string_3 te-xt