Question

I have created nested cursor which basically compares column values of one table To column values of another and returns the closest match.

Contents of Tables are say :

(ColumnName and Values are as below)
Table A

**Names**
MandarinOrange
SweetApple
SourApple
AppleThatTasteslikeGrapes

Table B

**Names**
PlainOrange
SourOrange
Grapple
.
.
.

So the Cursor1 (outer cursor) takes each name from table1 and compares with all the names in Table2 and returns me the closest match.Cursor 2 (inner) is to retrieve the names in table 2

I am looking to see, if there is a way to acheive the same avaoiding using Cursors
(because it is too slow)

Answer 1

Avoid cursors is always a better practice and in your case, I think it’s also achievable. The key to it is the calculation you perform in order to evaluate the comparison result.

One solution is to create a function takes two strings and return a 1/0 value as the comparison result. Then you can call the function as part of the SELECT statement and save the cursor iteration.

Here’s an example for such a function:

CREATE FUNCTION fn_Compare
(
    @firstValue     varchar(50),
    @secondValue    varchar(50)
)
RETURNS bit
AS
BEGIN
    DECLARE @Result bit
    SET @Result = 0 --False by default

    --!Here goes your specific logic for comparing string!  
    IF @firstValue = @secondValue
        SET @Result = 1

    RETURN @Result

END
GO

--Use it in a sentance
SELECT dbo.fn_Compare('TEST', 'TEST') AS Match --True
SELECT dbo.fn_Compare('TEST', 'TEST2') AS Match --False

--Use it in a query
SELECT 
    name,
    name,
    dbo.fn_Compare(name, name) AS Match
FROM sysobjects
WHERE 
    Type = 'u'

--Cleanup
DROP FUNCTION fn_Compare

I hope this helps.