uniqueidentifier Type

[qhjghz]

Hi all, need some help. I have a table called my_table say, and there is a uniqueidentifier field in that table say my_column.
When I execute this query, I get back a row

select * from my_table where
my_column = 'B844EC98-F509-4F41-BC42-301DD22F6A12'

But, when I change the string value by changing any of the characters, I get an error stating

Server: Msg 8169, Level 16, State 2, Line 1
Syntax error converting from a character string to uniqueidentifier.


However, if I change any of the numbers in the string, I do not get any data, but also I get no errors.
Can anyone please explain why this happens? Is it so, that for uniqueidentifier columns, there are only a fixed set of characters, but numbers may alter? I am new to SQL Server, so it will be great if someone helps me out(I have replaced one character by those characters which are already present in the string itself, I don't get any errors. But suppose I replace D by X, I get an error)

[azimmer]

Hi all, need some help. I have a table called my_table say, and there is a uniqueidentifier field in that table say my_column.
When I execute this query, I get back a row

select * from my_table where
my_column = 'B844EC98-F509-4F41-BC42-301DD22F6A12'

But, when I change the string value by changing any of the characters, I get an error stating

Server: Msg 8169, Level 16, State 2, Line 1
Syntax error converting from a character string to uniqueidentifier.


However, if I change any of the numbers in the string, I do not get any data, but also I get no errors.
Can anyone please explain why this happens? Is it so, that for uniqueidentifier columns, there are only a fixed set of characters, but numbers may alter? I am new to SQL Server, so it will be great if someone helps me out(I have replaced one character by those characters which are already present in the string itself, I don't get any errors. But suppose I replace D by X, I get an error)

IMHO it's best to treat uniqueidentifiers SQL Server internal structures which you do not want to manipulate by hand like that. They are usually assigned to column automatically (by setting the default to the newid() function), and one usually uses them to select a specific row (or rows) -- usually in joins, sometimes in other operations (esp. DELETE). If I were you I wouldn't want to make out the internals of uniqueidentifiers unless there's absolutely no other way.
If you do want to play around with it keep in mind: each position is a hex digit, so valid letters are 'A'..'F' only.

[almaz]

However, if I change any of the numbers in the string, I do not get any data, but also I get no errors.
Can anyone please explain why this happens? Is it so, that for uniqueidentifier columns, there are only a fixed set of characters, but numbers may alter? I am new to SQL Server, so it will be great if someone helps me out(I have replaced one character by those characters which are already present in the string itself, I don't get any errors. But suppose I replace D by X, I get an error)

Uniqueidentifier type (also called GUID, "Globally Unique IDentifier") have a standard text representation of "8chars-4chars-4chars-4chars-12chars", where each character is a hexadecimal digit (0-9, A-F). See GUID for more information.

[qhjghz]

IMHO it's best to treat uniqueidentifiers SQL Server internal structures which you do not want to manipulate by hand like that. They are usually assigned to column automatically (by setting the default to the newid() function), and one usually uses them to select a specific row (or rows) -- usually in joins, sometimes in other operations (esp. DELETE). If I were you I wouldn't want to make out the internals of uniqueidentifiers unless there's absolutely no other way.
If you do want to play around with it keep in mind: each position is a hex digit, so valid letters are 'A'..'F' only.

"If you do want to play around with it keep in mind: each position is a hex digit, so valid letters are 'A'..'F' only" That's the answer I was looking for. Thanks a lot. That is the reason why when I try to substitute "b" BY "X", it does not work, but when I replace it by "A", it works