SQL VARBINARY

What is the SQL VARBINARY data type?

Stores variable-length binary data such as files, images, or encrypted values.

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Compatible dialects for SQL VARBINARY:

SQL VARBINARY Full Explanation

VARBINARY is a binary string data type that holds variable-length sequences of bytes. Unlike BINARY, which right-pads values to a fixed length, VARBINARY only stores the actual number of bytes inserted, up to the declared maximum. It is ideal for data that is not human-readable, including images, documents, encryption hashes, and compressed objects.The maximum length depends on the database:- SQL Server: up to 8,000 bytes for VARBINARY(n) and 2 GB for VARBINARY(MAX).- MySQL: up to 65,535 bytes (subject to row size limits).Storage is byte-oriented, so character set and collation rules do not apply. Most functions that work on strings (e.g., LIKE) are not meaningful on VARBINARY. Use hexadecimal or parameterized input when inserting literal values.Caveats:1. Implicit conversions from strings may change data if the string uses a character set with multi-byte characters.2. Sorting and comparison are byte-by-byte, not lexicographic text order.3. Large values can impact memory and network bandwidth. Prefer streaming APIs (e.g., FILESTREAM, BLOB streaming) for very large blobs.4. In replication or backup scenarios, large VARBINARY columns can slow operations.

SQL VARBINARY Syntax

-- Column definition
column_name VARBINARY(length)

-- SQL Server unlimited length
column_name VARBINARY(MAX)

-- Casting
CAST(expression AS VARBINARY(length));

-- MySQL literal insert using hex
INSERT INTO t(photo) VALUES (0xFFD8FFE0);

SQL VARBINARY Parameters

length (integer) - Maximum number of bytes to store. Use MAX in SQL Server for up to 2 GB.

Example Queries Using SQL VARBINARY

-- 1. Table with a VARBINARY column (SQL Server)
CREATE TABLE UserFiles (
  id INT PRIMARY KEY,
  file_data VARBINARY(MAX),
  uploaded_at DATETIME DEFAULT GETDATE()
);

-- 2. Insert an image using a parameterized query (conceptual)
INSERT INTO UserFiles(id, file_data) VALUES (1, ?);  -- bind binary parameter

-- 3. Store an SHA-256 hash (MySQL)
CREATE TABLE logins (
  user_id INT PRIMARY KEY,
  password_hash VARBINARY(32)
);
INSERT INTO logins VALUES (5, UNHEX('5E884898DA28047151D0E56F8DC62927...'));

-- 4. Retrieve file size in KB (SQL Server)
SELECT id, DATALENGTH(file_data)/1024 AS size_kb FROM UserFiles;

Expected Output Using SQL VARBINARY

Queries create tables that can hold binary data, insert binary values, or return metadata such as the byte length
Result sets will show binary literals in hex or as depending on client tooling

Use Cases with SQL VARBINARY

Storing user-uploaded files inside the database when a file system is not feasible
Saving cryptographic hashes or salts for authentication workflows
Keeping compressed JSON or XML blobs
Persisting binary license keys or tokens
Recording sensor data that is naturally binary

Common Mistakes with SQL VARBINARY

Declaring VARBINARY without a length (required in MySQL and non-MAX SQL Server versions)
Confusing VARBINARY with VARCHAR and losing data due to character encoding
Attempting to search binary columns with LIKE or standard text operators
Forgetting that VARBINARY comparisons are case-sensitive byte comparisons
Ignoring row size limits in MySQL/InnoDB, causing insertion errors

First Introduced In

SQL Server 7.0 and MySQL 4.1

Frequently Asked Questions

What is the difference between VARBINARY and BINARY?

BINARY pads values to the fixed length specified, which can waste space. VARBINARY stores only the bytes you insert, so it is more space-efficient for variable-length data.

Can I index a VARBINARY column?

Yes. Both MySQL and SQL Server allow indexing VARBINARY, but large keys slow inserts and lookups. Consider hashing long binary values before indexing.

How large can VARBINARY be?

SQL Server offers up to 8,000 bytes for VARBINARY(n) and 2 GB with VARBINARY(MAX). MySQL supports up to 65,535 bytes, limited by row size.

How do I convert VARBINARY to text?

Use CAST or CONVERT with an appropriate character type and code page, for example CAST(binary_col AS VARCHAR(100)) in SQL Server. Make sure the bytes represent valid text in that encoding.