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SQL is null and = null [duplicate]
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In SQL, a comparison between a null value and any other value (including another null) using a comparison operator (eg =, !=, <, etc) will result in a null, which is considered as false for the purposes of a where clause (str...
Does order of where clauses matter in SQL?
...e and figure out the most efficient way to satisfy that query.
I know the SQL Server query optimizer will pick a suitable index - no matter which order you have your two conditions in. I assume other RDBMS will have similar strategies.
What does matter is whether or not you have a suitable index f...
Difference between a theta join, equijoin and natural join
...nces are fine, I want to show how the relational algebra is transformed to SQL and what the actual value of the 3 concepts is.
The key concept in your question is the idea of a join. To understand a join you need to understand a Cartesian Product (the example is based on SQL where the equivalent i...
SQL Server ':setvar' Error
I am trying to create some script variables in T-SQL as follows:
4 Answers
4
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Dynamic SELECT TOP @var In SQL Server
How can I have a dynamic variable setting the amount of rows to return in SQL Server? Below is not valid syntax in SQL Server 2005+:
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What are the pros and cons of performing calculations in sql vs. in your application
...th, and disk io if the aggregates can be done inside indexes)
convenience (sql is not the best language for complex work - especially not great for procedural work, but very good for set-based work; lousy error-handling, though)
As always, if you do bring the data back to the app-server, minimisin...
How to insert a line break in a SQL Server VARCHAR/NVARCHAR string
...ully, but ran into a problem with it: once you have more than about 480 +, SQL Server will start complaining that your query is too deeply nested. My solution was instead to use Rob Cooper's answer instead, but with a much longer and more obscure token.
– Marcus Downing
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JdbcTemplate queryForInt/Long is deprecated in Spring 3.2.2. What should it be replaced by?
...see its current implementation:
@Deprecated
public int queryForInt(String sql, Object... args) throws DataAccessException {
Number number = queryForObject(sql, args, Integer.class);
return (number != null ? number.intValue() : 0);
}
which may lead you to think that if the result set is em...
SQL Server, convert a named instance to default instance?
I need to convert a named instance of SQL server 2005, to a default instance.
7 Answers
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Why do people hate SQL cursors so much? [closed]
...ors. Defeating an RDBMS optimization. And running really slowly.
Simple SQL rewrites to replace nested cursor loops with joins and a single, flat cursor loop can make programs run in 100th the time. [They thought I was the god of optimization. All I did was replace nested loops with joins. Sti...