What are the Real Limits of NVARCHAR and VARCHAR in SQL, and How Can I Avoid Concatenation Truncation?

Practical limits of NVARCHAR and VARCHAR in SQL and how to avoid connection truncation

Understanding NVARCHAR

Contrary to what you may think, NVARCHAR(MAX) does not have a 4,000 character limit. It can store up to (and in some cases more than) 2GB of data. If the data type (nvarchar(n)) is specified, up to 4,000 characters are allowed, but max allows large objects to be stored without specifying a specific length.

4,000 Character Limit Misunderstanding

The 4,000 character limit you are encountering may result from string concatenation, the behavior of which depends on the data types involved:

• varchar(n) varchar(n): truncated to 8,000 characters
• nvarchar(n) nvarchar(n): Truncate to 4,000 characters
• [n]varchar(max) [n]varchar(max): No truncation
• varchar(n) nvarchar(n): truncated to 4,000 characters (the result is nvarchar(4,000))

In your case, the error may occur when trying to concatenate a varchar(4001-8000) string to an nvarchar type string, resulting in truncation.

Solve the problem

To avoid connection truncation:

• Make sure all string literals use the N prefix, especially strings in the 4001-8000 character range.
• Concatenate strings in NVARCHAR(MAX) variables to avoid NVARCHAR(4,000) truncation issues.

View long SQL string

To view long SQL strings in SSMS without restrictions:

• Switch to "Results to Grid" mode
• Use XML PATH query:

<code class="language-sql">select @SQL as [processing-instruction(x)] FOR XML PATH</code>

You can avoid formatting issues by enclosing the SQL string in processing instructions.

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