SQL PRINT not working in certain instance

Question

In the following if I try to place a print after the BEGIN statement it doesn't work, when I remove everything within the BEGIN-END statement and place a print it does work;

SET @SQL = 'IF (((SELECT fldLT FROM #zArray) = ''p'') OR ((SELECT fldMF FROM #zArray) <> -1))
            BEGIN
                SET @X = '+@Z+' * ((SELECT fldLF FROM #zArray) / 100))

                IF (CAST((SELECT fldMF FROM #zArray) AS FLOAT) > '+@X+')
                    BEGIN
                        SET @X = (CAST((SELECT fldMF FROM #zArray) AS FLOAT))
                    END                         
                END'   

EXEC sp_executesql @SQL, N'@X NVARCHAR(50),@Z NVARCHAR(50)', @X, @Z

Is there something wrong with the following code that would cause the print statement not to work?

    'SET @X = '+@Z+' * ((SELECT fldLF FROM #zArray) / 100))

                IF (CAST((SELECT fldMF FROM #zArray) AS FLOAT) > '+@X+')
                    BEGIN
                        SET @X = (CAST((SELECT fldMF FROM #zArray) AS FLOAT))
END'

Answer 1

I don't understand why you're concatenating your parameters and you're using them again, in the procedure sp_executesql.

I modified a little your query, removing the concatenation of the parameters and using the REPLACE function, to replace the placeholders with your parameters:

DECLARE @X NVARCHAR(50) = '123'
DECLARE  @Z NVARCHAR(50) = '123'
DECLARE @SQL NVARCHAR(MAX)

SET @SQL = 'IF (((SELECT fldLT FROM #zArray) = ''p'') OR ((SELECT fldMF FROM #zArray) <> -1))
            BEGIN
                SET @paramX = @paramZ * ((SELECT fldLF FROM #zArray) / 100))

                IF (CAST((SELECT fldMF FROM #zArray) AS FLOAT) > @paramX)
                    BEGIN
                        SET @paramX = (CAST((SELECT fldMF FROM #zArray) AS FLOAT))
                    END                         
                END'   

SET @SQL = REPLACE(@SQL,'@paramX',@X)
SET @SQL = REPLACE(@SQL,'@paramZ',@Z)

PRINT @SQL

EXEC sp_executesql @SQL

For me, the PRINT statement is working fine.

Answer 2

Your need SQL Statement to passed as a string not the variable being using in the dynamic sql

DECLARE @Xr NVARCHAR(50) = '1000351' DECLARE  @Zr NVARCHAR(50) = '46546321'
DECLARE @SQL NVARCHAR(MAX)
SET @SQL = 'IF (((SELECT fldLT FROM #zArray) = ''p'') OR ((SELECT fldMF FROM #zArray) <> -1))
            BEGIN
                SET @X = @Z * ((SELECT fldLF FROM #zArray) / 100))

                IF (CAST((SELECT fldMF FROM #zArray) AS FLOAT) > @X)
                    BEGIN
                        SET @X = (CAST((SELECT fldMF FROM #zArray) AS FLOAT))
                    END                         
                END '   
PRINT @SQL
EXEC sp_executesql @SQL, 
                    N'@X NVARCHAR(50),@Z NVARCHAR(50)', 
                    @X = @Xr, 
                    @Z = @Zr

PRINT Result

IF (((SELECT fldLT FROM #zArray) = 'p') OR ((SELECT fldMF FROM #zArray) <> -1))
            BEGIN
                SET @X = 46546321 * ((SELECT fldLF FROM #zArray) / 100))

                IF (CAST((SELECT fldMF FROM #zArray) AS FLOAT) > 1000351)
                    BEGIN
                        SET @X = (CAST((SELECT fldMF FROM #zArray) AS FLOAT))
                    END                         
                END