Loop through rows of a query in T-SQL? - sql

Question

I have the following T-SQL script:
declare #Name nvarchar
declare data cursor for
select Name from MyDB.dbo.MyTable;
OPEN data;
-- Perform the first fetch.
FETCH NEXT FROM data;
-- Check ##FETCH_STATUS to see if there are any more rows to fetch.
WHILE ##FETCH_STATUS = 0
BEGIN
-- This is executed as long as the previous fetch succeeds.
FETCH NEXT FROM data INTO #Name;
Print 'Name: ' + #Name
END
CLOSE data;
DEALLOCATE data;
GO
I want to make a script that will compare each of the strings in a first column with each of the strings in the second column.
The problem is, I don't know how to loop through each of the rows and take a separate string value.
The code above prints only the first value in the query result.
What am I doing wrong?

Answer 1

To compare all values from one column to all values in another column you don't need a cursor, a simple join will do the work - since you didn't provide sample data and also not desired results, I had to make my own:
Create and populate sample table (Please save us this step in your future questions)
CREATE TABLE MyTable
(
Id int identity(1,1),
Name1 char(3),
Name2 char(3)
)
INSERT INTO MyTable (Name1, Name2) VALUES
('abc','def'),('zyx','abc'),
('ghi','jkl'),('yza','ghi'),
('mno','pqr'),('nml','mno'),('pqr','qpo'),
('stu','vwx'),('wvu','tsr'),('kji','hgf')
The query:
SELECT T1.Id, T1.Name1, T1.Name2, T2.Id, T2.Name1, T2.Name2
FROM MyTable T1
JOIN MyTable T2 ON T1.Name1 = T2.Name2
Result:
Id Name1 Name2 Id Name1 Name2
1 abc def 2 zyx abc
3 ghi jkl 4 yza ghi
5 mno pqr 6 nml mno
7 pqr qpo 5 mno pqr

Answer 2

You probably don't want to use a Cursor.
Are your columns in the same table? If so this is as simple as this;
-- Show All rows with [DIFFERENT] Name and Name2 fields
SELECT
Name,
Name2
FROM [MyDB].[dbo].[MyTable]
WHERE
Name <> Name2
-- Show All rows with [SAME] Name and Name2 fields
SELECT
Name,
Name2
FROM [MyDB].[dbo].[MyTable]
WHERE
Name = Name2
If not you will need to post the table definitions and names of columns to get a more concrete example