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what is the difference between GROUP BY and ORDER BY in sql
...regation functions on non-grouped columns (such as SUM, COUNT, AVG, etc).
TABLE:
ID NAME
1 Peter
2 John
3 Greg
4 Peter
SELECT *
FROM TABLE
ORDER BY NAME
=
3 Greg
2 John
1 Peter
4 Peter
SELECT Count(ID), NAME
FROM TABLE
GROUP BY NAME
=
1 Greg
1 John
2 Peter
SELECT NAME
FROM TABLE
GROUP B...
How to use mysql JOIN without ON condition?
...ian product -- that is, every possible combination of 1 row from the first table and 1 row from the second. The cross join for a table with three rows ('a', 'b', and 'c') and a table with four rows (say 1, 2, 3, 4) would have 12 rows.
In practice, if you want to do a cross join, then use cross joi...
WITH (NOLOCK) vs SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED
...se the set transaction isolation level statement, it will apply to all the tables in the connection, so if you only want a nolock on one or two tables use that; otherwise use the other.
Both will give you dirty reads. If you are okay with that, then use them. If you can't have dirty reads, then co...
Mean per group in a data.frame [duplicate]
...ype of operation is exactly what aggregate was designed for:
d <- read.table(text=
'Name Month Rate1 Rate2
Aira 1 12 23
Aira 2 18 73
Aira 3 19 45
Ben 1 53 19
Ben 2 22 87
Ben 3 19 ...
How to understand nil vs. empty vs. blank in Ruby
...
I made this useful table with all the cases:
blank?, present? are provided by Rails.
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The model backing the context has changed since the database was created
...eded to use the model with a hash of the schema stored in an
EdmMetadata table that is created with a database (when Code First is
the one creating the database). Existing databases won’t have the
EdmMetadata table and so won’t have the hash…and the implementation
today will throw if t...
How to pass an array into a SQL Server stored procedure
...our database, create the following two objects:
CREATE TYPE dbo.IDList
AS TABLE
(
ID INT
);
GO
CREATE PROCEDURE dbo.DoSomethingWithEmployees
@List AS dbo.IDList READONLY
AS
BEGIN
SET NOCOUNT ON;
SELECT ID FROM @List;
END
GO
Now in your C# code:
// Obtain your list of ids to send, this...
How to vertically align into the center of the content of a div with defined width/height?
...I have found you have four options:
Version 1: Parent div with display as table-cell
If you do not mind using the display:table-cell on your parent div, you can use of the following options:
.area{
height: 100px;
width: 100px;
background: red;
margin:10px;
text-align: center;
...
What is the difference between DAO and Repository patterns?
...lection of objects.
DAO would be considered closer to the database, often table-centric.
Repository would be considered closer to the Domain, dealing only in Aggregate Roots.
Repository could be implemented using DAO's, but you wouldn't do the opposite.
Also, a Repository is generally a narro...
LIKE vs CONTAINS on SQL Server
...e an index, since it starts with a wildcard, so will always require a full table scan.
The CONTAINS query should be:
SELECT * FROM table WHERE CONTAINS(Column, 'test');
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