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How do I create a unique constraint that also allows nulls?
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SQL Server 2008 +
You can create a unique index that accept multiple NULLs with a WHERE clause. See the answer below.
Prior to SQL Server 2008
You cannot create a UNIQUE constraint and allow NULLs. You need set a default v...
How do I add a foreign key to an existing SQLite table?
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You can't.
Although the SQL-92 syntax to add a foreign key to your table would be as follows:
ALTER TABLE child ADD CONSTRAINT fk_child_parent
FOREIGN KEY (parent_id)
REFERENCES parent(id);
SQLite doesn't supp...
SQL select only rows with max value on a column [duplicate]
...ed you need the content column as well.
This is a very common question in SQL: find the whole data for the row with some max value in a column per some group identifier. I heard that a lot during my career. Actually, it was one the questions I answered in my current job's technical interview.
It ...
How to create materialized views in SQL Server?
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They're called indexed views in SQL Server - read these white papers for more background:
Creating an Indexed View
Improving Performance with SQL Server 2008 Indexed Views
Basically, all you need to do is:
create a regular view
create a clustered in...
How to do a LIKE query in Arel and Rails?
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is this protected against SQL injections?
– sren
May 28 '12 at 2:17
7
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Difference between EXISTS and IN in SQL?
What is the difference between the EXISTS and IN clause in SQL?
21 Answers
21
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How can I truncate a datetime in SQL Server?
...y to truncate a datetime value (as to remove hours minutes and seconds) in SQL Server 2008?
13 Answers
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How to print VARCHAR(MAX) using Print Statement?
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This works for me on SQL 2008 R2 SP2 (10.50.1600) using either CAST() or CONVERT(), and on SQL 2008 SP2 (10.0.5500).
– user593806
Nov 5 '13 at 10:13
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SQL JOIN and different types of JOINs
What is a SQL JOIN and what are different types?
6 Answers
6
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Not equal != operator on NULL
Could someone please explain the following behavior in SQL?
11 Answers
11
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