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What's the difference between INNER JOIN, LEFT JOIN, RIGHT JOIN and FULL JOIN? [duplicate]
...These pictures don't do it for me. Why is the top right picture not simply SELECT * FROM TableA;? Why is the top left picture not simply SELECT * FROM TableB;? Why is the top middle picture not SELECT * FROM A INTERSECT SELECT * FROM B ? etc
– onedaywhen
Sep 9 ...
How to order by with union in SQL?
Is it possible to order when the data is come from many select and union it together? Such as
8 Answers
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What is the error “Every derived table must have its own alias” in MySQL?
...er), which can the be used to refer to it in the rest of the outer query.
SELECT ID FROM (
SELECT ID, msisdn FROM (
SELECT * FROM TT2
) AS T
) AS T
In your case, of course, the entire query could be replaced with:
SELECT ID FROM TT2
...
What does $$ mean in the shell?
...e mktemp option -t is now deprecated (I think because of problems with the char -). Use mktemp ${tempfoo}.XXXXXX these days. I take the liberty to update your post.
– Sebastian
Jan 10 '14 at 11:44
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Postgres: INSERT if does not exist already
...onditional INSERT in PostgreSQL:
INSERT INTO example_table
(id, name)
SELECT 1, 'John'
WHERE
NOT EXISTS (
SELECT id FROM example_table WHERE id = 1
);
CAVEAT This approach is not 100% reliable for concurrent write operations, though. There is a very tiny race condition between...
How to select rows with no matching entry in another table?
...
Here's a simple query:
SELECT t1.ID
FROM Table1 t1
LEFT JOIN Table2 t2 ON t1.ID = t2.ID
WHERE t2.ID IS NULL
The key points are:
LEFT JOIN is used; this will return ALL rows from Table1, regardless of whether or not there is a matching row i...
PostgreSQL function for last inserted ID
...e:
INSERT INTO persons (lastname,firstname) VALUES ('Smith', 'John');
SELECT currval('persons_id_seq');
The name of the sequence must be known, it's really arbitrary; in this example we assume that the table persons has an id column created with the SERIAL pseudo-type. To avoid relying on thi...
Rails select helper - Default selected value, how?
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This should do it:
<%= f.select :project_id, @project_select, :selected => params[:pid] %>
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Select distinct using linq [duplicate]
...
myList.GroupBy(test => test.id)
.Select(grp => grp.First());
Edit: as getting this IEnumerable<> into a List<> seems to be a mystery to many people, you can simply write:
var result = myList.GroupBy(test => test.id)
.S...
Change the selected value of a drop-down list with jQuery
...
jQuery's documentation states:
[jQuery.val] checks, or selects, all the radio buttons, checkboxes, and select options that match the set of values.
This behavior is in jQuery versions 1.2 and above.
You most likely want this:
$("._statusDDL").val('2');
...