Update if not exists statement
If I have a simple table with 2 columns and a composite primary key consisting of both columns, how do I rename one of the columns but only if it doesn't cause a primary conflict?
Here's a simplified example.
Take the following table:
User | Role
------|----------------
Joe | User
Joe | Administrator
Brian | User
Anna | Administrator
Anna | Admin
Suppose I want to write the following query:
UPDATE UserRoles Set Role = 'Admin' WHERE Role = 'Administrator'
Without using cursors, how do I change my SQL Update statement to avoid renaming Anna (because that user already has the Admin role), but still rename Joe?
Is that even possible using set based SQL or is using a cursor the only way?
Thanks.
sql-server t-sql sql-server-2014 update
asked Dec 10 '15 at 23:20
Lambo JayapalanLambo Jayapalan
102127
add a comment |
If I have a simple table with 2 columns and a composite primary key consisting of both columns, how do I rename one of the columns but only if it doesn't cause a primary conflict?
Here's a simplified example.
Take the following table:
User | Role
------|----------------
Joe | User
Joe | Administrator
Brian | User
Anna | Administrator
Anna | Admin
Suppose I want to write the following query:
UPDATE UserRoles Set Role = 'Admin' WHERE Role = 'Administrator'
Without using cursors, how do I change my SQL Update statement to avoid renaming Anna (because that user already has the Admin role), but still rename Joe?
Is that even possible using set based SQL or is using a cursor the only way?
Thanks.
sql-server t-sql sql-server-2014 update
asked Dec 10 '15 at 23:20
Lambo JayapalanLambo Jayapalan
102127
add a comment |
If I have a simple table with 2 columns and a composite primary key consisting of both columns, how do I rename one of the columns but only if it doesn't cause a primary conflict?
Here's a simplified example.
Take the following table:
User | Role
------|----------------
Joe | User
Joe | Administrator
Brian | User
Anna | Administrator
Anna | Admin
Suppose I want to write the following query:
UPDATE UserRoles Set Role = 'Admin' WHERE Role = 'Administrator'
Without using cursors, how do I change my SQL Update statement to avoid renaming Anna (because that user already has the Admin role), but still rename Joe?
Is that even possible using set based SQL or is using a cursor the only way?
Thanks.
sql-server t-sql sql-server-2014 update
asked Dec 10 '15 at 23:20
Lambo JayapalanLambo Jayapalan
102127
If I have a simple table with 2 columns and a composite primary key consisting of both columns, how do I rename one of the columns but only if it doesn't cause a primary conflict?
Here's a simplified example.
Take the following table:
User | Role
------|----------------
Joe | User
Joe | Administrator
Brian | User
Anna | Administrator
Anna | Admin
Suppose I want to write the following query:
UPDATE UserRoles Set Role = 'Admin' WHERE Role = 'Administrator'
Without using cursors, how do I change my SQL Update statement to avoid renaming Anna (because that user already has the Admin role), but still rename Joe?
Is that even possible using set based SQL or is using a cursor the only way?
Thanks.
sql-server t-sql sql-server-2014 update
sql-server t-sql sql-server-2014 update
asked Dec 10 '15 at 23:20
Lambo JayapalanLambo Jayapalan
102127
asked Dec 10 '15 at 23:20
Lambo JayapalanLambo Jayapalan
102127
asked Dec 10 '15 at 23:20
Lambo JayapalanLambo Jayapalan
102127
asked Dec 10 '15 at 23:20
Lambo JayapalanLambo Jayapalan
102127
asked Dec 10 '15 at 23:20
Lambo JayapalanLambo Jayapalan
102127
102127
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
One way is
UPDATE a
SET [Role]= 'Admin'
FROM UserRoles a
WHERE a.[Role]= 'Administrator'
AND NOT EXISTS
(
SELECT NULL
FROM dbo.UserRoles b
WHERE b.[User] = a.[User] AND b.[Role] = 'Admin'
);
edited 12 mins ago
Paul White♦
52.1k14278450
answered Dec 10 '15 at 23:32
a1ex07a1ex07
7,32621632
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
One way is
UPDATE a
SET [Role]= 'Admin'
FROM UserRoles a
WHERE a.[Role]= 'Administrator'
AND NOT EXISTS
(
SELECT NULL
FROM dbo.UserRoles b
WHERE b.[User] = a.[User] AND b.[Role] = 'Admin'
);
edited 12 mins ago
Paul White♦
52.1k14278450
answered Dec 10 '15 at 23:32
a1ex07a1ex07
7,32621632
add a comment |
One way is
UPDATE a
SET [Role]= 'Admin'
FROM UserRoles a
WHERE a.[Role]= 'Administrator'
AND NOT EXISTS
(
SELECT NULL
FROM dbo.UserRoles b
WHERE b.[User] = a.[User] AND b.[Role] = 'Admin'
);
edited 12 mins ago
Paul White♦
52.1k14278450
answered Dec 10 '15 at 23:32
a1ex07a1ex07
7,32621632
add a comment |
One way is
UPDATE a
SET [Role]= 'Admin'
FROM UserRoles a
WHERE a.[Role]= 'Administrator'
AND NOT EXISTS
(
SELECT NULL
FROM dbo.UserRoles b
WHERE b.[User] = a.[User] AND b.[Role] = 'Admin'
);
edited 12 mins ago
Paul White♦
52.1k14278450
answered Dec 10 '15 at 23:32
a1ex07a1ex07
7,32621632
One way is
UPDATE a
SET [Role]= 'Admin'
FROM UserRoles a
WHERE a.[Role]= 'Administrator'
AND NOT EXISTS
(
SELECT NULL
FROM dbo.UserRoles b
WHERE b.[User] = a.[User] AND b.[Role] = 'Admin'
);
edited 12 mins ago
Paul White♦
52.1k14278450
answered Dec 10 '15 at 23:32
a1ex07a1ex07
7,32621632
edited 12 mins ago
Paul White♦
52.1k14278450
edited 12 mins ago
Paul White♦
52.1k14278450
edited 12 mins ago
Paul White♦
52.1k14278450
52.1k14278450
answered Dec 10 '15 at 23:32
a1ex07a1ex07
7,32621632
answered Dec 10 '15 at 23:32
a1ex07a1ex07
7,32621632
answered Dec 10 '15 at 23:32
a1ex07a1ex07
7,32621632
7,32621632
add a comment |
add a comment |
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