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SQL join: selecting the last records in a one-to-many relationship
Suppose I have a table of customers and a table of purchases. Each purchase belongs to one customer. I want to get a list of all customers along with their last purchase in one SELECT statement. What is the best practice? Any advice on building indexes?
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Good Hash Function for Strings
...le check - The hashCode() return value will be used by Java to map to some table index before storing the object. So, if the hashCode() returns m, it does something like (m mod k) to get an index of the table of size k. Is that right?
– whitehat
Oct 17 '15 at 2...
Using margin:auto to vertically-align a div
...he three elements have to be nested like so:
.container {
display: table;
height: 100%;
position: absolute;
overflow: hidden;
width: 100%;
}
.helper {
#position: absolute;
#top: 50%;
display: table-cell;
vertical-align: middle;
}
.content {
#position: rela...
jQuery document.createElement equivalent?
...is.$OuterDiv = $('<div></div>')
.hide()
.append($('<table></table>')
.attr({ cellSpacing : 0 })
.addClass("text")
)
;
Update: I thought I'd update this post since it still gets quite a bit of traffic. In the comments below there's some discussi...
Best way to store password in database [closed]
...gets a hold of your database, they can still use what are known as rainbow tables to be able to "decrypt" the password (at least those that show up in the rainbow table). To get around this, developers add a salt to passwords which, when properly done, makes rainbow attacks simply infeasible to do. ...
MySQL Great Circle Distance (Haversine formula)
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@FosAvance Yes, this query would work if you have markers table with id, lan and lng fields.
– Pavel Chuchuva
Mar 29 '14 at 23:08
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“Insert if not exists” statement in SQLite
...te database. I am trying to insert values ( users_id , lessoninfo_id ) in table bookmarks , only if both do not exist before in a row.
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How to check existence of user-define table type in SQL Server 2008?
I have a user-defined table type. I want to check it's existence before editing in a patch using OBJECT_ID(name, type) function.
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Simulating group_concat MySQL function in Microsoft SQL Server 2005?
...to do this. Lots of ideas out there, though.
Best one I've found:
SELECT table_name, LEFT(column_names , LEN(column_names )-1) AS column_names
FROM information_schema.columns AS extern
CROSS APPLY
(
SELECT column_name + ','
FROM information_schema.columns AS intern
WHERE extern.table_n...
SQLite - increase value by a certain number
is it possible to increase a certain value in a table by a certain number without reading last value and afterwards updating it?
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