Suppose we have created a tblUser User in sql server:
CREATE TABLE tblUser(
ID BIGINT IDENTITY,
[Name] VARCHAR(100)
)
Now
executing following sql query:
SELECT $ROWID,[Name]
FROM tblUser
We will get error
message:
Invalid pseudocolumn "$ROWID".
Cause: In sql server there only two pseudocolumn
1. $IDENTITY
2. $ROWGUID
Here $ROWID is not valid pseudocolumn
Solution:
We can think these pseudo columns as
alias of identity columns and ROWGUIDCOL columns
respectively of any table.
$IDENTITY:
To use this column table must have
identity column. For example we have created a table as follow:
CREATE TABLE tblUser(
ID BIGINT IDENTITY,
[Name] VARCHAR(100)
)
INSERT tblUser VALUES('Scott'),('Greg')
Now
executing following sql query:
SELECT $IDENTITY,[Name]
FROM tblUser
Output:
ID
|
Name
|
1
|
Scott
|
2
|
Greg
|
$ROWGUID:
To use this column table must have ROWGUIDCOL column. For example we
have created a table as follow:
CREATE TABLE tblUser(
ID UNIQUEIDENTIFIER
ROWGUIDCOL DEFAULT(NEWID()),
[Name] VARCHAR(100)
)
INSERT tblUser(Name) VALUES('Scott'),('Greg')
Now
executing following sql query:
SELECT $ROWGUID,[Name]
FROM tblUser
Sample output:
ID
|
Name
|
F3F1DEA5-3F06-4A2A-B12F-10E9157F037C
|
Scott
|
73CF2944-5682-4741-98C1-29F5F2B2A9F1
|
Greg
|
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