HASHBYTES (Transact-SQL) - SQL Server (2024)

HASHBYTES ( '<algorithm>', { @input | 'input' } ) <algorithm>::= MD2 | MD4 | MD5 | SHA | SHA1 | SHA2_256 | SHA2_512 

DECLARE @HashThis NVARCHAR(32); SET @HashThis = CONVERT(NVARCHAR(32),'dslfdkjLK85kldhnv$n000#knf'); SELECT HASHBYTES('SHA2_256', @HashThis); 

CREATE TABLE dbo.Test1 (c1 NVARCHAR(32)); INSERT dbo.Test1 VALUES ('This is a test.'); INSERT dbo.Test1 VALUES ('This is test 2.'); SELECT HASHBYTES('SHA2_256', c1) FROM dbo.Test1; 

------------------------------------------- 0x741238C01D9DB821CF171BF61D72260B998F7C7881D90091099945E0B9E0C2E3 0x91DDCC41B761ACA928C62F7B0DA61DC763255E8247E0BD8DCE6B22205197154D (2 row(s) affected) 

I am an expert in database management systems, particularly SQL Server and related technologies. I have extensive hands-on experience and a deep understanding of the concepts discussed in the provided article. Allow me to demonstrate my expertise by breaking down the key elements covered in the article dated 05/23/2023.

The article primarily focuses on the HASHBYTES function in SQL Server and its application in various Microsoft platforms, including Azure SQL Database, Azure SQL Managed Instance, Azure Synapse Analytics, Analytics Platform System (PDW), and the SQL analytics endpoint in Microsoft Fabric Warehouse.

Here are the key concepts discussed in the article:

1. Function Overview:

   • HASHBYTES is a function in SQL Server used to return the MD2, MD4, MD5, SHA, SHA1, or SHA2 hash of its input.
   • The syntax is HASHBYTES('<algorithm>', { @input | 'input' }).
   • Supported algorithms include MD2, MD4, MD5, SHA, SHA1, SHA2_256, and SHA2_512.

2. Syntax Conventions:

   • The article provides Transact-SQL syntax conventions for using HASHBYTES.
   • <algorithm>::= denotes the possible algorithms, and single quotation marks are required around the algorithm name.

3. Arguments:

   • <algorithm>: Identifies the hashing algorithm to be used, and it is a required argument.
   • @input: Specifies a variable containing the data to be hashed. It can be varchar, nvarchar, or varbinary.
   • 'input': Specifies an expression that evaluates to a character or binary string to be hashed.

4. Output:

   • The output size conforms to the algorithm standard: 128 bits (16 bytes) for MD2, MD4, and MD5; 160 bits (20 bytes) for SHA and SHA1; 256 bits (32 bytes) for SHA2_256, and 512 bits (64 bytes) for SHA2_512.

5. Version-specific Information:

   • For SQL Server 2012 (11.x) and later, there are no specific limitations on input values.
   • For SQL Server 2014 (12.x) and earlier, allowed input values are limited to 8000 bytes.

6. Deprecation Warning:

   • The MD2, MD4, MD5, SHA, and SHA1 algorithms are deprecated starting with SQL Server 2016 (13.x).
   • It is recommended to use SHA2_256 or SHA2_512 instead, though older algorithms will continue working, raising a deprecation event.

7. Examples:

   • The article provides examples of using HASHBYTES, including returning the hash of a variable and the hash of a table column.

8. Return Value:

   • The return value is of type varbinary with a maximum size of 8000 bytes.

9. Remarks:

   • The article suggests considering alternatives like CHECKSUM or BINARY_CHECKSUM to compute hash values.

10. See Also:

    • The article references related functions and topics such as encryption algorithms, CHECKSUM_AGG, CHECKSUM, and BINARY_CHECKSUM.

In summary, the article comprehensively covers the usage, syntax, and considerations related to the HASHBYTES function in SQL Server, providing valuable information for database developers and administrators.