Iterate through a list of strings In SQL Server?

Question

How do you access the value within a list in T-SQL?

I have a SQL statement that loops through and counts how many times a value appears in a specific column in

Answer 1

What you created is not a list but a table variable. So how to Iterate over a table. Below is a simple example and I think you can proceed after if you understand it:

(Note: Cursors are not efficient when it comes to performance and large tables)

DECLARE @MyList TABLE (Value NVARCHAR(50))
INSERT INTO @MyList VALUES ('Data1')
INSERT INTO @MyList VALUES ('Data2')
INSERT INTO @MyList VALUES ('Data3')
INSERT INTO @MyList VALUES ('Data4')
INSERT INTO @MyList VALUES ('Data5')
INSERT INTO @MyList VALUES ('Data6')
INSERT INTO @MyList VALUES ('Data7')
INSERT INTO @MyList VALUES ('Data8')

DECLARE @value VARCHAR(50)

DECLARE db_cursor CURSOR FOR  
SELECT Value FROM @MyList
OPEN db_cursor   
FETCH NEXT FROM db_cursor INTO @value   

WHILE @@FETCH_STATUS = 0   
BEGIN   
       PRINT @value

       -- PUT YOUR LOGIC HERE
       -- MAKE USE OR VARIABLE @value wich is Data1, Data2, etc...

       FETCH NEXT FROM db_cursor INTO @value   
END   

CLOSE db_cursor   
DEALLOCATE db_cursor

Prints:

Data1
Data2
Data3
Data4
Data5
Data6
Data7
Data8

So you have inside @value variable Data, Data2 .. etc . I think this solves your problem.

Alternative way is using a WHILE loop + OFFSET + FETCH NEXT :

DECLARE @MyList TABLE (Value NVARCHAR(50))
INSERT INTO @MyList VALUES ('Data1')
INSERT INTO @MyList VALUES ('Data2')
INSERT INTO @MyList VALUES ('Data3')
INSERT INTO @MyList VALUES ('Data4')
INSERT INTO @MyList VALUES ('Data5')
INSERT INTO @MyList VALUES ('Data6')
INSERT INTO @MyList VALUES ('Data7')
INSERT INTO @MyList VALUES ('Data8')

DECLARE @COUNTER INT = 0;
DECLARE @MAX INT = (SELECT COUNT(*) FROM @MyList)
DECLARE @VALUE VARCHAR(50);

WHILE @COUNTER < @MAX
BEGIN

SET @VALUE = (SELECT VALUE FROM
      (SELECT (ROW_NUMBER() OVER (ORDER BY (SELECT NULL))) [index] , Value from @MyList) R 
       ORDER BY R.[index] OFFSET @COUNTER 
       ROWS FETCH NEXT 1 ROWS ONLY);

PRINT @VALUE

SET @COUNTER = @COUNTER + 1

END

You get the same result