How to use integer variable in Dynamic Query - sql

Question

I have created the below dynamic query to check if length of particular attribute is more than 50 or not. I am trying to make the length size also dynamic but getting below error.
Msg 207, Level 16, State 1, Line 7
Invalid column name '50'.
The query I came up with is as below. I am pretty new to SQL and trying to resolve this error. Thanks!
--Rule A.5.Summary :- Length
/* The 'DECLARE' statements below are used to
define standard test parameters and their datatypes. The values for these
parameters will be updated for each of the DQ dimensions/KDEs being tested */
DECLARE #DQ_DIMENSION_RULE VARCHAR(100)
DECLARE #RULE_NO VARCHAR(100)
DECLARE #TABLE_NAME VARCHAR(100)
DECLARE #DATA_ATTRIBUTE VARCHAR(100)
DECLARE #LENGTH_SIZE INT
/*The 'SET' statements below are used to
assign values to each of the test parameters declared above.
The values will depend on the DQ dimension/KDE being tested.*/
SET #DQ_DIMENSION_RULE = 'Accuracy - Negative Values'
SET #RULE_NO = 'A.4'
SET #TABLE_NAME = 'TRANSACTIONS'
SET #DATA_ATTRIBUTE = 'TRANSACTIONID'
SET #LENGTH_SIZE = 50
DECLARE #sql nvarchar(max) = N'
SELECT
' + QUOTENAME(#DQ_DIMENSION_RULE, '''') + N' AS [DQ_Dimension_Rule],
' + QUOTENAME(#RULE_NO, '''') + N' AS [Rule_No],
' + QUOTENAME(#TABLE_NAME, '''') + N' AS [Table Name],
' + QUOTENAME(#DATA_ATTRIBUTE, '''') + N' AS [Column Name],
case when SUM(CASE WHEN LEN(' + QUOTENAME(#DATA_ATTRIBUTE) + N') >' + QUOTENAME(#LENGTH_SIZE) + N' THEN 1 ELSE 0 END) > 0 then ''Y'' else ''N'' end as [Potential Issue(Y/N)]
FROM ' + QUOTENAME(#TABLE_NAME)
-- The data from 'SELECT' statement is being inserted into the summary table
--INSERT INTO summary
EXEC sp_executesql #sql;

Answer 1

You should not put QUOTENAME() around the integer values, the integers are not table names that you need to quote, etc.
You should just convert the integers to strings, without quotes...
DECLARE #sql nvarchar(max) = N'
SELECT
' + QUOTENAME(#DQ_DIMENSION_RULE, '''') + N' AS [DQ_Dimension_Rule],
' + QUOTENAME(#RULE_NO, '''') + N' AS [Rule_No],
' + QUOTENAME(#TABLE_NAME, '''') + N' AS [Table Name],
' + QUOTENAME(#DATA_ATTRIBUTE, '''') + N' AS [Column Name],
case when SUM(CASE WHEN LEN(' + QUOTENAME(#DATA_ATTRIBUTE) + N') >' + CAST(#LENGTHSIZE AS NVARCHAR(MAX)) + N' THEN 1 ELSE 0 END) > 0 then ''Y'' else ''N'' end as [Potential Issue(Y/N)]
FROM ' + QUOTENAME(#TABLE_NAME)
QUOTENAME(#LENGTHSIZE) => CAST(#LENGTHSIZE AS NVARCHAR(MAX))

Answer 2

Better than injecting it, parametrise it:
DECLARE #DQ_DIMENSION_RULE VARCHAR(100);
DECLARE #RULE_NO VARCHAR(100);
DECLARE #TABLE_NAME sysname; --Correct data type for object names
DECLARE #DATA_ATTRIBUTE VARCHAR(100);
DECLARE #LENGTH_SIZE INT;
SET #DQ_DIMENSION_RULE = 'Accuracy - Negative Values';
SET #RULE_NO = 'A.4';
SET #TABLE_NAME = 'TRANSACTIONS';
SET #DATA_ATTRIBUTE = 'TRANSACTIONID';
SET #LENGTH_SIZE = 50;
DECLARE #sql nvarchar(max) = N'
SELECT
' + QUOTENAME(#DQ_DIMENSION_RULE, '''') + N' AS [DQ_Dimension_Rule],
' + QUOTENAME(#RULE_NO, '''') + N' AS [Rule_No],
N' + QUOTENAME(#TABLE_NAME, '''') + N' AS [Table Name],
' + QUOTENAME(#DATA_ATTRIBUTE, '''') + N' AS [Column Name],
case when SUM(CASE WHEN LEN(' + QUOTENAME(#DATA_ATTRIBUTE) + N') > #LENGTH_SIZE THEN 1 ELSE 0 END) > 0 then ''Y'' else ''N'' end as [Potential Issue(Y/N)]
FROM ' + QUOTENAME(#TABLE_NAME) + N';';
EXEC sys.sp_executesql #sql, N'#LENGTH_SIZE int', #LENGTH_SIZE;
I've also changed the data type of your dynamic object and ensured that it the literal string is injected with a nvarchar notation character too.