各种常见数据库分页实现

  因为数据量过大，如果一次性查询会耗用大量时间以及性能，因此对数据进行分页显示变得尤为重要，以下就列出一些常用数据库的sql分页实现。

1.MySQL实现分页
MySQL实现分页效果比较简单，只有一个limit关键字就可以解决。

示例：SELECT username,password FROM tb_user WHERE id = 1 LIMIT 100,10;
具体：select * from tableName where 条件 limit 当前页码*页面容量-1,页面容量

2.Oralce实现分页

SELECT *
  FROM (SELECT A.*, ROWNUM RN FROM (SELECT * FROM tableName order by id) A WHERE ROWNUM <=20)
WHERE RN >= 11;

select count(*) from tableName where 条件


3.Sqlserver实现分页

sqlserver由于版本的不同，分页的实现方式也各不相同。

SQL 2000 用临时表解决，通过在临时表中增加自增列解决RowNumber。
DECLARE @Start INT
DECLARE @End INT
SELECT @Start = 14000,@End = 14050

CREATE TABLE #employees (RowNumber INT IDENTITY(1,1),
LastName VARCHAR(100),FirstName VARCHAR(100),
EmailAddress VARCHAR(100))

INSERT INTO #employees (LastName, FirstName, EmailAddress)
SELECT LastName, FirstName, EmailAddress
FROM Employee
ORDER BY LastName, FirstName, EmailAddress
SELECT LastName, FirstName, EmailAddress
FROM #employees
WHERE RowNumber > @Start AND RowNumber <= @End

DROP TABLE #employees

GO　　

SQL 2005/2008 由于支持了Row_Number于是通过派生表的方式解决（两个嵌套）
DECLARE @Start INT
DECLARE @End INT
SELECT @Start = 14000,@End = 14050

SELECT LastName, FirstName, EmailAddress
FROM (SELECT LastName, FirstName, EmailAddress,
ROW_NUMBER() OVER (ORDER BY LastName, FirstName, EmailAddress) AS RowNumber
FROM Employee) EmployeePage
WHERE RowNumber > @Start AND RowNumber <= @End
ORDER BY LastName, FirstName, EmailAddress
GO
　　

SQL 2005/2008 或者用CTE的方式实现，和派生表一样，就是好看点，执行计划都一样。
DECLARE @Start INT
DECLARE @End INT
SELECT @Start = 14000,@End = 14050;
WITH EmployeePage AS
(SELECT LastName, FirstName, EmailAddress,
ROW_NUMBER() OVER (ORDER BY LastName, FirstName, EmailAddress) AS RowNumber
FROM Employee)
SELECT LastName, FirstName, EmailAddress
FROM EmployeePage
WHERE RowNumber > @Start AND RowNumber <= @End
ORDER BY LastName, FirstName, EmailAddress
GO
　　
SQL SERVER 2012 比较给力支持了OFFSET，于是一个Select结束战斗,另外在2012里，如果前面加上TOP（50），那么执行计划就会少读很多行数据（读的精准了），提高性能。
SELECT top(50) LastName, FirstName, EmailAddress
FROM Employee
ORDER BY LastName, FirstName, EmailAddress
OFFSET 14000 ROWS
FETCH NEXT 50 ROWS ONLY;

4.DB2实现分页
Db2实现分页与SQL Server类似, 但是可以不对资料排序(起始位置从1开始)

对资料排序
select * from (
    select t.*, ROW_NUMBER() OVER(ORDER BY CARD_ID asc) AS ROWNUM from CARD t ) a
where ROWNUM > 20 and ROWNUM <=30

不对资料排序
select * from (
    select t.*, ROW_NUMBER() OVER() AS ROWNUM from CARD t ) a
where ROWNUM > 20 and ROWNUM <=30


以上为各种常见数据库分页语句，留存备用。