Loop through Query and Update field - sql

Question

I'm trying to loop through a fields defined in a query to an update statement.
I have the following SQL:
Declare #SQL varchar(max)
#SQL= 'Select [a],[b],[c],[d],[e]....[z]
From Table1;'
I want to be able to loop through all the fields [a]-[z] and update via the following statement:
Update Table 1
Set [a] = Case when [a] = 'Not at all' Then 0
when [a] = 'Very Much' Then 10 End
Field names are not actually [a]..[z]; I can't run the the update statement on the whole table, only a specific set of field names.
Struggling to write it programatically in SQL Server.

Answer 1

Declare #SQL varchar(max)
Declare #name varchar(100)
DECLARE #getid CURSOR
Set #getid = cursor for
SELECT name
FROM
sys.dm_exec_describe_first_result_set('Select [a],[b],[c],[d],[e]....[z]
From Table1', NULL, 0)
Open #getid
FETCH NEXT
FROM #getid INTO #name
WHILE ##FETCH_STATUS = 0
BEGIN
SET #SQL = 'Update Table1
Set ' + #name + ' = Case when ' + #name +'= ''Very Much'' Then ''10''
when ' + #name + ' = ''Not at all'' Then ''0''
Else ' + #name + ' End'
Exec(#SQL)
FETCH NEXT
FROM #getid INTO #name
END
CLOSE #getid
DEALLOCATE #getid
Basically dm_exec_describe_first_result_set is grabbing the fieldnames and outputting it as a recordset. Then we are just passing the the each of the records to #name and use it form our update statement and then executing it for each record passed.
Hope this helps someone else! Curious to see if there is a better way.

Answer 2

I think if you want to make it a little more generic I would do something like the following code. This will allow you to not have to write the specific query for every table you want to do this to and you could potentially filter out columns you do not want in the future.
To be clear, I borrowed the SQL to do the actual UPDATE from #Dale-K post and just made it pretty.
DECLARE #strSQL NVARCHAR(1000)
DECLARE #strTable NVARCHAR(100)
DECLARE #strColName VARCHAR(100)
SET #strTable = N'Table1'
CREATE TABLE #COLUMNS(ColName varchar(100))
SET #strSQL = ' select COLUMN_NAME
from INFORMATION_SCHEMA.COLUMNS
where TABLE_NAME = #TableName and DATA_TYPE in (''nvarchar'', ''varchar'')'
INSERT INTO #COLUMNS
EXEC sp_executeSQL #strSQL, N'#TableName nvarchar(100)', #TableName = #strTable
DECLARE csrColumns CURSOR LOCAL FORWARD_ONLY FOR
SELECT ColName FROM #COLUMNS
OPEN csrColumns
FETCH csrColumns INTO #strColName
WHILE ##FETCH_STATUS = 0
BEGIN
SET #strSQL = N'UPDATE ' + #strTable + '
SET ' + #strColName + ' = CASE WHEN ' + #strColName +'= ''Very Much'' THEN ''10''
WHEN ' + #strColName + ' = ''Not at all'' THEN ''0''
ELSE ' + #strColName + ' END'
exec sp_ExecuteSQL #strSQL
FETCH csrColumns INTO #strColName
END
CLOSE csrColumns
DEALLOCATE csrColumns