sample_456.md

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How to generate GUID values

Before you begin:

The result is returned in a format like that of the following sample:
{557cf400-1a04-11d3-9a73-0000f81ef32e}

See also:

• Generating random UUID values
• Generating sequential UUID values

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Code:

DO declare

LOCAL cGUID, cGUIDString, cGUID1
cGUID = REPLICATE(CHR(0), 16)  && 128 bits

IF CoCreateGuid(@cGUID) = 0
	cGUIDString = StringFromGUID(cGUID)
	? cGUID
	? cGUIDString
	
	* converting from String back to GUID
	cGUID1 = REPLICATE(CHR(0), 16)
	= CLSIDFromString(STRCONV(cGUIDString,5), @cGUID1)
	? cGUID1
ENDIF
* end of main

FUNCTION StringFromGUID(cGUID)
	LOCAL cBuffer, nBufsize
	nBufsize=128
	cBuffer = REPLICATE(CHR(0), nBufsize*2)
	= StringFromGUID2(cGUID, @cBuffer, nBufsize)
	cBuffer = SUBSTR(cBuffer, 1, AT(CHR(0)+CHR(0), cBuffer))
RETURN STRCONV(cBuffer, 6)

PROCEDURE declare
	DECLARE INTEGER CoCreateGuid IN ole32 STRING @pguid

	DECLARE INTEGER CLSIDFromString IN ole32;
		STRING lpsz, STRING @pclsid

	DECLARE INTEGER StringFromGUID2 IN ole32;
		STRING rguid, STRING @lpsz, INTEGER cchMax  

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Listed functions:

CLSIDFromString
CoCreateGuid
StringFromGUID2

Comment:

The GUID is a unique 128-bit integer used for CLSIDs and interface identifiers.

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Having a connection to SQL Server, Guids can be generated with the NewId() function.

FUNCTION NewGuid() As String  
	IF SQLEXEC(1, "SELECT NewId() As guid", "csGuid") > 0  
		RETURN csGuid.guid  
	ELSE  
		RETURN NULL  
	ENDIF

Another way is using the Scriptlet.TypeLib COM. Note that you must create a new instance of the class for each Guid to be generated, which probably produces some overhead.

obj = CreateObject("Scriptlet.TypeLib")  
? SUBSTR(obj.GUID,2,36)

After a simple test I can estimate that the COM procedure is 5 to 10% faster than the SQL one (local server); and API is the winner creating GUID 15-20 times faster than COM -- for example, 0.24 seconds versus 4 seconds per 10,000 guids created.

On the same computer C# code generated 1,000,000 guids in 1.05 seconds.

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