SQL에서 무작위로 행을 선택하는 방법은 무엇입니까?

SQL에서 무작위로 행을 선택하는 방법은 무엇입니까?

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MSSQL Server 2005를 사용하고 있습니다. 내 데이터베이스에는 "Id"와 "Name"이라는 두 개의 열과 약 2 개의 열이있는 "customerNames"테이블이 있습니다. 결과 1,000 개

매번 5 명의 고객을 무작위로 선택해야하는 기능을 만들고 있습니다. 누구나 쿼리를 실행할 때마다 임의의 5 행 (Id 및 Name)을 얻는 쿼리를 만드는 방법을 말해 줄 수 있습니까?

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SELECT TOP 5 Id, Name FROM customerNames
ORDER BY NEWID()

즉, 귀하의 질문에 대한보다 일반적인 답변을 얻으려면 모두이 페이지에 오는 것 같습니다.

SQL에서 임의의 행 선택

MySQL로 임의의 행을 선택하십시오.

SELECT column FROM table
ORDER BY RAND()
LIMIT 1

PostgreSQL로 임의의 행을 선택하십시오.

SELECT column FROM table
ORDER BY RANDOM()
LIMIT 1

Microsoft SQL Server에서 임의의 행을 선택하십시오.

SELECT TOP 1 column FROM table
ORDER BY NEWID()

IBM DB2로 임의의 행을 선택하십시오.

SELECT column, RAND() as IDX 
FROM table 
ORDER BY IDX FETCH FIRST 1 ROWS ONLY

Oracle에서 무작위 레코드를 선택하십시오.

SELECT column FROM
( SELECT column FROM table
ORDER BY dbms_random.value )
WHERE rownum = 1

sqlite로 임의의 행을 선택하십시오.

SELECT column FROM table 
ORDER BY RANDOM() LIMIT 1

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SELECT TOP 5 Id, Name FROM customerNames ORDER BY NEWID()

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아마 이 사이트가 도움이 될 것입니다.

클릭 연결을 원하지 않는 사람들을 위해 :

SELECT TOP 1 column FROM table
ORDER BY NEWID()

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누군가가 PostgreSQL 솔루션을 원할 경우 :

select id, name
from customer
order by random()
limit 5;

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여기에는 멋진 Microsoft SQL Server 2005 솔루션이 있습니다. 큰 결과 집합으로 작업하는 문제를 처리합니다 (내가 아는 질문은 아님).

큰 테이블에서 임의로 행 선택 http://msdn.microsoft.com/en-us/library/cc441928.aspx

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random () LIMIT 5;로 테이블 이름 순서에서 선택 *;

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이것은 오래된 질문이지만 행 수가 많은 테이블에 새 필드 (NEWID () 또는 ORDER BY rand ())를 적용하려고하면 비용이 많이 듭니다. 증분적이고 고유 한 ID가 있고 (구멍이없는 경우) GUID를 적용하거나 모든 단일 행과 유사하고 상위 X #을 가져 오는 대신 선택할 X ID ID를 계산하는 것이 더 효율적입니다.

DECLARE @maxValue int = (select max(id) from [TABLE])
DECLARE @minValue int = (select min(id) from [TABLE])
DECLARE @randomId1 int, @randomId2 int, @randomId3 int, @randomId4 int, @randomId5 int
SET @randomId1 = ((@maxValue + 1) - @minValue) * Rand() + @minValue
SET @randomId2 = ((@maxValue + 1) - @minValue) * Rand() + @minValue
SET @randomId3 = ((@maxValue + 1) - @minValue) * Rand() + @minValue
SET @randomId4 = ((@maxValue + 1) - @minValue) * Rand() + @minValue
SET @randomId5 = ((@maxValue + 1) - @minValue) * Rand() + @minValue

--select @maxValue as MaxValue, @minValue as MinValue
--  , @randomId1 as SelectedId1
--  , @randomId2 as SelectedId2
--  , @randomId3 as SelectedId3
--  , @randomId4 as SelectedId4
--  , @randomId5 as SelectedId5


select *from[TABLE] el
    where el.id in (@randomId1, @randomId2, @randomId3, @randomId4, @randomId5)

If you wanted to select many more rows I would look into populating a #tempTable with an ID and a bunch of rand() values then using each rand() value to scale to the min-max values. That way you do not have to define all of the @randomId1...n parameters. I've included an example below using a cte to populate the initial table.

DECLARE @NumItems int = 100;

DECLARE @maxValue int = (select max(id) from [TABLE])
DECLARE @minValue int = (select min(id) from [TABLE])

with cte (n) as (select 1 union all select n+1 from cte where n < @NumItems)
select cast( ((@maxValue + 1) - @minValue) * rand(cast(newid() as varbinary(100))) + @minValue as int) as tp into #Nt
from 
cte
select * from  #Nt ntt
inner join [TABLE] i 
        on i.id = ntt.tp
drop table #Nt

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I have found this to work best for big data.

`SELECT TOP 1 Column_Name FROM dbo.Table TABLESAMPLE(1 PERCENT);`

TABLESAMPLE(n ROWS) or TABLESAMPLE(n PERCENT) is random but need to add the TOP n to get the correct sample size.

Using NEWID() is very slow on large tables.

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If you have a table with millions of rows and care about the performance, this could be a better answer:

SELECT * FROM Table1
WHERE (ABS(CAST(
  (BINARY_CHECKSUM
  (keycol1, NEWID())) as int))
  % 100) < 10

https://msdn.microsoft.com/en-us/library/cc441928.aspx

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As I explained in this article, in order to shuffle the SQL result set, you need to use a database-specific function call.

Note that sorting a large result set using a RANDOM function might turn out to be very slow, so make sure you do that on small result sets.

If you have to shuffle a large result set and limit it afterward, then it's better to use something like the Oracle SAMPLE(N) or the TABLESAMPLE in SQL Server or PostgreSQL instead of a random function in the ORDER BY clause.

So, assuming we have the following database table:

And the following rows in the song table:

| id | artist                          | title                              |
|----|---------------------------------|------------------------------------|
| 1  | Miyagi & Эндшпиль ft. Рем Дигга | I Got Love                         |
| 2  | HAIM                            | Don't Save Me (Cyril Hahn Remix)   |
| 3  | 2Pac ft. DMX                    | Rise Of A Champion (GalilHD Remix) |
| 4  | Ed Sheeran & Passenger          | No Diggity (Kygo Remix)            |
| 5  | JP Cooper ft. Mali-Koa          | All This Love                      |

Oracle

On Oracle, you need to use the DBMS_RANDOM.VALUE function, as illustrated by the following example:

SELECT
    artist||' - '||title AS song
FROM song
ORDER BY DBMS_RANDOM.VALUE

When running the aforementioned SQL query on Oracle, we are going to get the following result set:

| song                                              |
|---------------------------------------------------|
| JP Cooper ft. Mali-Koa - All This Love            |
| 2Pac ft. DMX - Rise Of A Champion (GalilHD Remix) |
| HAIM - Don't Save Me (Cyril Hahn Remix)           |
| Ed Sheeran & Passenger - No Diggity (Kygo Remix)  |
| Miyagi & Эндшпиль ft. Рем Дигга - I Got Love      |

Notice that the songs are being listed in random order, thanks to the DBMS_RANDOM.VALUE function call used by the ORDER BY clause.

SQL Server

On SQL Server, you need to use the NEWID function, as illustrated by the following example:

SELECT
    CONCAT(CONCAT(artist, ' - '), title) AS song
FROM song
ORDER BY NEWID()

When running the aforementioned SQL query on SQL Server, we are going to get the following result set:

| song                                              |
|---------------------------------------------------|
| Miyagi & Эндшпиль ft. Рем Дигга - I Got Love      |
| JP Cooper ft. Mali-Koa - All This Love            |
| HAIM - Don't Save Me (Cyril Hahn Remix)           |
| Ed Sheeran & Passenger - No Diggity (Kygo Remix)  |
| 2Pac ft. DMX - Rise Of A Champion (GalilHD Remix) |

Notice that the songs are being listed in random order, thanks to the NEWID function call used by the ORDER BY clause.

PostgreSQL

On PostgreSQL, you need to use the random function, as illustrated by the following example:

SELECT
    artist||' - '||title AS song
FROM song
ORDER BY random()

When running the aforementioned SQL query on PostgreSQL, we are going to get the following result set:

| song                                              |
|---------------------------------------------------|
| 2Pac ft. DMX - Rise Of A Champion (GalilHD Remix) |
| JP Cooper ft. Mali-Koa - All This Love            |
| Ed Sheeran & Passenger - No Diggity (Kygo Remix)  |
| HAIM - Don't Save Me (Cyril Hahn Remix)           |
| Miyagi & Эндшпиль ft. Рем Дигга - I Got Love      |

Notice that the songs are being listed in random order, thanks to the random function call used by the ORDER BY clause.

MySQL

On MySQL, you need to use the RAND function, as illustrated by the following example:

SELECT
  CONCAT(CONCAT(artist, ' - '), title) AS song
FROM song
ORDER BY RAND()

When running the aforementioned SQL query on MySQL, we are going to get the following result set:

| song                                              |
|---------------------------------------------------|
| HAIM - Don't Save Me (Cyril Hahn Remix)           |
| Ed Sheeran & Passenger - No Diggity (Kygo Remix)  |
| Miyagi & Эндшпиль ft. Рем Дигга - I Got Love      |
| 2Pac ft. DMX - Rise Of A Champion (GalilHD Remix) |
| JP Cooper ft. Mali-Koa - All This Love            |

Notice that the songs are being listed in random order, thanks to the RAND function call used by the ORDER BY clause.

참고URL : https://stackoverflow.com/questions/580639/how-to-randomly-select-rows-in-sql