sql server - PHP mssql_query errors when converting date and/or time from character string

I am using PHP to query some data on SQL Server 2008 R2 and receiving the following errors:

• PHP Warning: mssql_query(): message: Conversion failed when converting date and/or time from character string. (severity 16) in /var/www/html/BSC_Entry.php on line 14
• PHP Warning: mssql_query(): General SQL Server error: Check messages from the SQL Server (severity 16) in /var/www/html/BSC_Entry.php on line 14

Here's the code block:

  3 <?php // Initialise all database actions
  4     //IP of server
  5     $server = 'x.x.x.x';
  6 
  7     // Connection to MSSQL - possibly use password file
  8     $link = mssql_connect($server, 'user', 'pass');
  9     if (!$link) {
 10         die('Something went wrong while connecting to MSSQL');
 11     }
 12 
 13     // Declare query to return BSC_Name, BSC_Owner and  
 14     $qBSCInfo = mssql_query('SELECT * FROM dbo.BSC_Info;', $link);
 15 
 16 ?>
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Initially, I was passing the SQL below as a parameter to mssql_query, but after receiving the errors, created the database view above 'BSC_Info' (with appropriate permissions) in case the query was too complex for mssql_query to handle:

SELECT DISTINCT 
    dbo.BSC.BSC_ID,
    dbo.BSC.BSC_Name, 
    dbo.BSC.BSC_Owner, 
    DATEDIFF(M, MAX(CONVERT(DATETIME, LEFT(dbo.BSCDataSet.DatePeriod, 4) 
                      + RIGHT(dbo.BSCDataSet.DatePeriod, 2) + '01')), CONVERT(DATETIME, LEFT(CONVERT(VARCHAR, GETDATE(), 120), 4) + RIGHT(LEFT(CONVERT(VARCHAR, GETDATE(), 
                      120), 7), 2) + '01')) AS Periods_to_Current
FROM dbo.BSC 
LEFT OUTER JOIN dbo.BSCDataSet 
ON dbo.BSC.BSC_ID = dbo.BSCDataSet.BSC_ID
GROUP BY dbo.BSC.BSC_ID, dbo.BSC.BSC_Name, dbo.BSC.BSC_Owner
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To clarify, the query works in SQL Server Management Studio returning some fields from a table along with the difference (in months) between the current date and an earlier date (stored in the database as a VARCHAR - YYYYMM format). In order to prevent any issues with partial months, I've set the compared dates to the first day of the month. I am sure there's a more graceful way of doing this, but I have very little SQL Server experience, or PHP for that matter!

Data types are:

• BSC_ID - numeric(5,0)
• BSC_Name - varchar(50)
• BSC_Owner - varchar(50)
• Periods_to_Current - int

Any help would be much appreciated. Cheers all!