Variables are not allowed in the %ls statement

 In SQL Server, Error Code 112 stating "Variables are not allowed in the %ls statement" generally means that you cannot directly use variables in certain statements or contexts.

Since the %ls statement in this context likely refers to a scenario where you're trying to use a variable in a dynamic SQL or command execution, you need to use an approach that supports dynamic SQL execution.

To address this, you can use sp_executesql or EXEC with a constructed command string. Here’s how to properly construct and execute a command involving xp_cmdshell using dynamic SQL:

Example: Using xp_cmdshell with Dynamic Path:

Enable xp_cmdshell (if not already enabled):

-- Enable advanced options
EXEC sp_configure 'show advanced options', 1;
RECONFIGURE;

-- Enable xp_cmdshell
EXEC sp_configure 'xp_cmdshell', 1;
RECONFIGURE;

Construct and execute the command:

DECLARE @dir_path NVARCHAR(255);
DECLARE @cmd NVARCHAR(4000);

-- Set the directory path
SET @dir_path = 'C:\Your\Directory\Path';

-- Construct the command string
SET @cmd = 'dir "' + @dir_path + '"';

-- Execute the command using xp_cmdshell
EXEC xp_cmdshell @cmd;

Using sp_executesql for dynamic SQL: If you encounter contexts where variables are not allowed directly, you can dynamically construct the SQL statement and execute it using sp_executesql.

DECLARE @dir_path NVARCHAR(255);
DECLARE @cmd NVARCHAR(4000);

-- Set the directory path
SET @dir_path = 'C:\Your\Directory\Path';

-- Construct the command string
SET @cmd = N'dir "' + @dir_path + '"';

-- Execute the command using xp_cmdshell
EXEC xp_cmdshell @cmd;

Example: Dynamic SQL Execution with sp_executesql

To use sp_executesql in a more general dynamic SQL scenario:

DECLARE @sql NVARCHAR(MAX);
DECLARE @tableName NVARCHAR(255);

-- Set the table name
SET @tableName = N'myTable';

-- Construct the SQL statement
SET @sql = N'SELECT * FROM ' + QUOTENAME(@tableName);

-- Execute the SQL statement
EXEC sp_executesql @sql;

Note:

• Ensure Proper String Concatenation: Double-check that your command string is correctly constructed and includes necessary quotes, especially if paths or names contain spaces.
• Permissions: Ensure you have the necessary permissions to execute xp_cmdshell.
• Enable xp_cmdshell: Ensure xp_cmdshell is enabled as it is disabled by default for security reasons.

If these steps do not resolve the issue, please provide more specific details or the exact SQL command you're trying to execute, so I can offer more targeted assistance.

ORDER BY items must appear in the select list if SELECT DISTINCT is specified

 Msg 145, Level 15, State 1, Line 1
ORDER BY items must appear in the select list if SELECT DISTINCT is specified.

This message occurs when you are doing a SELECT DISTINCT combined with the ORDER BY clause and one of the columns in the ORDER BY is not specified as one of the columns in the SELECT DISTINCT.

SELECT DISTINCT orderid
FROM [dbo].[Orders]
ORDER BY [OrderDate] DESC

Msg 145, Level 15, State 1, Line 1
ORDER BY items must appear in the select list if SELECT DISTINCT is specified.

Instead of using the DISTINCT clause, you can use the GROUP BY clause to get the unique records from a table.  

SELECT orderid
FROM [dbo].[Orders]
GROUP BY orderid
ORDER BY MAX([OrderDate]) DESC