HASHBYTES (Transact-SQL)

Článok
09/03/2024

Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance Azure Synapse Analytics Analytics Platform System (PDW) SQL analytics endpoint in Microsoft Fabric Warehouse in Microsoft Fabric

Returns the MD2, MD4, MD5, SHA, SHA1, or SHA2 hash of its input in SQL Server.

Transact-SQL syntax conventions

Syntax

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

Arguments

<algorithm>
Identifies the hashing algorithm to be used to hash the input. This is a required argument with no default. The single quotation marks are required. Beginning with SQL Server 2016 (13.x), all algorithms other than SHA2_256, and SHA2_512 are deprecated.

@input
Specifies a variable containing the data to be hashed. @input is varchar, nvarchar, or varbinary.

'input'
Specifies an expression that evaluates to a character or binary string to be hashed.

The output 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.

Applies to: SQL Server 2012 (11.x) and later

For SQL Server 2014 (12.x) and earlier, allowed input values are limited to 8000 bytes.

Return Value

varbinary (maximum 8000 bytes)

Remarks

Consider using CHECKSUM or BINARY_CHECKSUM as alternatives to compute a hash value.

The MD2, MD4, MD5, SHA, and SHA1 algorithms are deprecated starting with SQL Server 2016 (13.x). Use SHA2_256 or SHA2_512 instead. Older algorithms will continue working, but they will raise a deprecation event.

Examples

Return the hash of a variable

The following example returns the SHA2_256 hash of the nvarchar data stored in variable @HashThis.

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

Return the hash of a table column

The following example returns the SHA2_256 hash of the values in column c1 in the table Test1.

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;

Here's the result set.

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

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