Kalmomi SQL TOP

TOP 子句

TOP 子句用于规定要返回的记录的数目。

对于拥有数千条记录的大型表来说，TOP 子句是非常有用的。

Kira:Kwamfani na duk tsarin nasiyar bayanai ba su da matukar TOP kalama ba.

FONSIYAWA SQL Server grammar:

SELECT TOP number|percent column_name(s)
FROM table_name

FONSIYAWA SQL SELECT TOP a yin daidai a cikin MySQL da Oracle

FONSIYAWA MySQL grammar

SELECT column_name(s)
FROM table_name
LIMIT number

Masanin

SELECT *
daga Persons
LIMIT 5

FONSIYAWA Oracle grammar

SELECT column_name(s)
FROM table_name
WHERE ROWNUM <= number

Masanin

SELECT *
daga Persons
WHERE ROWNUM <= 5

Tabbin farko (ama amfani da cewa masanin):

Tabbin Persons:

Id LastName FirstName Adress City
1 Adams John Oxford Street London
2 Bush George Fifth Avenue New York
3 Carter Thomas Changan Street Beijing
4 Obama Barack Pennsylvania Avenue Washington

FONSIYAWA SQL TOP masanin

Akanan, ake da iyawa samun farkon bayanai daya da biyu daga tabbin "Persons" a kwanan nan.

Ake da iya amfani da cewa SELECT da yake kwanan nan:

SELECT TOP 2 * daga Persons

Nauyin:

Id LastName FirstName Adress City
1 Adams John Oxford Street London
2 Bush George Fifth Avenue New York

FONSIYAWA SQL TOP PERCENT masanin

Akanan, ake da iyawa samun 50% na dukkanin bayanai daga tabbin "Persons" a kwanan nan.

Ake da iya amfani da cewa SELECT da yake kwanan nan:

SELECT TOP 50 PERCENT * daga Persons

Nauyin:

Id LastName FirstName Adress City
1 Adams John Oxford Street London
2 Bush George Fifth Avenue New York