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Does the join order matter in SQL?
...t matter. The queries will return same results, as long as you change your selects from SELECT * to SELECT a.*, b.*, c.*.
For (LEFT, RIGHT or FULL) OUTER joins, yes, the order matters - and (updated) things are much more complicated.
First, outer joins are not commutative, so a LEFT JOIN b is no...
MySQL, better to insert NULL or empty string?
...or an empty string using a bound variable but not for a NULL. This query:
SELECT *
FROM mytable
WHERE mytext = ?
will never match a NULL in mytext, whatever value you pass from the client. To match NULLs, you'll have to use other query:
SELECT *
FROM mytable
WHERE mytext IS NULL
...
When should I use semicolons in SQL Server?
...llowing two queries (copied from this post):
BEGIN TRY
BEGIN TRAN
SELECT 1/0 AS CauseAnException
COMMIT
END TRY
BEGIN CATCH
SELECT ERROR_MESSAGE()
THROW
END CATCH
BEGIN TRY
BEGIN TRAN
SELECT 1/0 AS CauseAnException;
COMMIT
END TRY
BEGIN CATCH
SELECT ERROR_MES...
How to simulate a button click using code?
...mes be a better choice in my experience than performClick(). If a user has selection sounds enabled, then performClick() could cause the user to hear two continuous selection sounds that are somewhat layered on top of each other which can be jarring. (One selection sound for the user's first button ...
Are Stored Procedures more efficient, in general, than inline statements on modern RDBMS's? [duplica
...he query plan that is generated is sub-optimal.
For example, if you send SELECT *
FROM table WHERE id BETWEEN 1 AND
99999999, the DBMS may select a
full-table scan instead of an index
scan because you're grabbing every row
in the table (so sayeth the
statistics). If this is the cached
...
LINQ with groupby and count
...(var line in data.GroupBy(info => info.metric)
.Select(group => new {
Metric = group.Key,
Count = group.Count()
})
.OrderBy(x => x.Metric))
{
Console.Wri...
Permutations in JavaScript?
...
If you notice, the code actually splits the chars into an array prior to do any permutation, so you simply remove the join and split operation
var permArr = [],
usedChars = [];
function permute(input) {
var i, ch;
for (i = 0; i < input.length; i++) ...
Sequence contains no elements?
...in dc.BlogPosts
where p.BlogPostID == id
select p).Single();
Also; if this is LINQ-to-SQL, then in the current version you get a slightly better behaviour if you use the form:
var id = ID;
BlogPost post = dc.BlogPosts.Single(p => p.BlogPostID == id);
...
Parallel.ForEach() vs. foreach(IEnumerable.AsParallel())
...the AsParallel() call, like:
var fibonacciNumbers = numbers.AsParallel().Select(n => ComputeFibonacci(n));
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When should I use a table variable vs temporary table in sql server?
... source for the data inserted to the table is from a potentially expensive SELECT statement then consider that using a table variable will block the possibility of this using a parallel plan.
If you need the data in the table to survive a rollback of an outer user transaction then use a table variab...