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Order by子句的用法

Order by子句的用法
Order by子句的用法

ORDER BY 子句 (Transact-SQL)

★语法;

ORDER BY order_by_expression

[ COLLATE collation_name ]

[ ASC | DESC ]

[ ,...n ]

[ ]

::=

{

OFFSET { integer_constant | offset_row_count_expression } { ROW | ROWS }

[

FETCH { FIRST | NEXT } {integer_constant |

fetch_row_count_expression } { ROW | ROWS } ONLY

]

}

★参数

order_by_expression

指定用于对查询结果集进行排序的列或表达式。可以将排序列指定为一个名称或列别名,也可以指定一个表示列在选择列表中所处位置的非负整数。

可以指定多个排序列。别名必须是唯一的。 ORDER BY 子句中的排序列的顺序定义了排序结果集的结构。也就是说,按第一列对结果集进行排序,然后按第二列对排序列表进行排序,依此类推。

ORDER BY 子句中引用的列名必须明确对应于选择列表中的列,或对应于 FROM 子句中指定的表中定义的列。

COLLATE collation_name

指定根据 collation_name 中指定的排序规则应执行的 ORDER BY 操作,而不是表或视图中所定义的列的排序规则。 collation_name 既可以是 Windows 排序规则名称,也可以是 SQL 排序规则名称。有关详细信息,请参阅排序规则和Unicode 支持。 COLLATE 仅适用于 char、varchar、nchar 和 nvarchar 类型的列。

ASC | DESC

指定按升序或降序排列指定列中的值。 ASC 按从最低值到最高值的顺序进行排序。 DESC 按从最高值到最低值的顺序进行排序。 ASC 是默认排序顺序。 Null 值被视为最低的可能值。

OFFSET { integer_constant | offset_row_count_expression } { ROW | ROWS } 指定开始从查询表达式返回行之前跳过的行数。该值可以是大于或等于零的整数常量或表达式。

offset_row_count_expression 可以是变量、参数或常数标量子查询。在使用子查询时,它无法引用在外部查询范围中定义的任何列。也就是说,它无法与外部查询相关联。

ROW 和 ROWS 是同义词,是为了与 ANSI 兼容而提供的。

在查询执行计划中,将在 TOP 查询运算符的 Offset 属性中显示偏移行数值。

FETCH { FIRST | NEXT } { integer_constant | fetch_row_count_expression } { ROW | ROWS } ONLY

指定在处理 OFFSET 子句后返回的行数。该值可以是大于或等于 1 的整数常量或表达式。

fetch_row_count_expression 可以是变量、参数或常数标量子查询。在使用子查询时,它无法引用在外部查询范围中定义的任何列。也就是说,它无法与外部查询相关联。

FIRST 和 NEXT 是同义词,是为了与 ANSI 兼容而提供的。

ROW 和 ROWS 是同义词,是为了与 ANSI 兼容而提供的。

在查询执行计划中,将在 TOP 查询运算符的 Rows 或 Top 属性中显示偏移行数值。

★最佳实践

避免将 ORDER BY 子句中的整数指定为选择列表中的列位置表示形式例如,虽然 SELECT ProductID, Name FROM Production.Production ORDER BY 2 等语句是有效的,但与指定实际列名相比,其他人并不容易理解该语句。此外,对选择列表的更改(如更改列顺序或添加新列)需要修改 ORDER BY 子句,以避免出现意外的结果。

在 SELECT TOP (N) 语句中,始终使用 ORDER BY 子句。这是以可预知的方式指明哪些行受 TOP 影响的唯一方法。

★互操作性

在与 SELECT…INTO 语句一起使用以从另一来源插入行时,ORDER BY 子句不能保证按指定的顺序插入这些行。

在视图中使用 OFFSET 和 FETCH 并不会更改该视图的 Updateability 属性。★限制和局限

ORDER BY 子句中的列数没有限制;但是,在 ORDER BY 子句中指定的列的总大小不能超过 8,060 个字节。

无法在 ORDER BY 子句中使用 ntext、text、image、geography、geometry 和 xml 类型的列。

在 order_by_expression 出现在排名函数中时,无法指定整数或常量。有关详细信息,请参阅OVER 子句 (Transact-SQL)。

如果已在 FROM 子句中指定了表名的别名,则在 ORDER BY 子句中只能使用该别名来限定其列。

如果 SELECT 语句包含以下子句或运算符之一,则必须在选择列表中定义在ORDER BY 子句中指定的列名和别名:

?UNION 运算符

?EXCEPT 运算符

?INTERSECT 运算符

?SELECT DISTINCT

此外,当语句包含 UNION、EXCEPT 或 INTERSECT 运算符时,必须在第一个(左侧)查询的选择列表中指定列名或列别名。

在使用 UNION、EXCEPT 或 INTERSECT 运算符的查询中,只允许在语句末尾使用ORDER BY。只有在顶级查询而不是子查询中指定了 UNION、EXCEPT 和INTERSECT 时,此限制才适用。请参阅后面的“示例”一节。

除非还指定了 TOP 子句或 OFFSET 和 FETCH 子句,否则,视图、内联函数、派生表和子查询中的 ORDER BY 子句无效。在这些对象中使用 ORDER BY 时,该子句仅用于确定由 TOP 子句或 OFFSET 和 FETCH 子句返回的行。 ORDER BY 不保证在查询这些构造时得到有序结果,除非在查询本身中也指定了 ORDER BY。

索引视图或使用 CHECK OPTION 子句定义的视图中不支持 OFFSET 和 FETCH。

可以在允许 TOP 和 ORDER BY 的任何查询中使用 OFFSET 和 FETCH,但具有以下限制:

?OVER 子句不支持 OFFSET 和 FETCH。

?无法在 INSERT、UPDATE、MERGE 和 DELETE 语句中直接指定 OFFSET 和FETCH,但可以在这些语句定义的子查询中指定 OFFSET 和 FETCH。例

如,在 INSERT INTO SELECT 语句中,可以在 SELECT 语句中指定 OFFSET 和 FETCH。

?在使用 UNION、EXCEPT 或 INTERSECT 运算符的查询中,只能在指定查询结果顺序的最终查询中指定 OFFSET 和 FETCH。

?不能在同一查询表达式(相同查询作用域中)中将 TOP 与 OFFSET 和FETCH 结合使用。

基本语法

本节中的示例说明了使用最低要求的语法的 ORDER BY 子句的基本功能。

A.指定在选择列表中定义的单个列

以下示例按数值 ProductID 列对结果集进行顺序。由于未指定特定的排序顺序,将使用默认顺序(升序)。

USE AdventureWorks2012;

GO

SELECT ProductID, Name FROM Production.Product

WHERE Name LIKE 'Lock Washer%'

ORDER BY ProductID;

B.指定未在选择列表中定义的列

以下示例按未包含在选择列表中的列对结果集进行排序,但 FROM 子句中指定的表中定义了该列。

USE AdventureWorks2012;

GO

SELECT ProductID, Name, Color

FROM Production.Product

ORDER BY ListPrice;

C.将别名指定为排序列

以下示例将列别名 SchemaName 指定为排序顺序列。

GO

SELECT name, SCHEMA_NAME(schema_id) AS SchemaName

FROM sys.objects

WHERE type = 'U'

ORDER BY SchemaName;

D.将表达式指定为排序列

以下示例将表达式作为排序列。表达式是使用 DATEPART 函数定义的,以便按员工的雇用年份对结果集进行排序。

USE AdventureWorks2012;

Go

SELECT BusinessEntityID, JobTitle, HireDate

FROM HumanResources.Employee

ORDER BY DATEPART(year, HireDate);

指定升序和降序排序顺序

A.指定降序

以下示例按 ProductID 数值列降序对结果集进行排序。

USE AdventureWorks2012;

GO

SELECT ProductID, Name FROM Production.Product

WHERE Name LIKE 'Lock Washer%'

ORDER BY ProductID DESC;

B.指定升序

以下示例按 Name 列升序对结果集进行排序。请注意,字符按字母顺序排序,而不是数值顺序。也就是说,10 排在 2 之前。

GO

SELECT ProductID, Name FROM Production.Product

WHERE Name LIKE 'Lock Washer%'

ORDER BY Name ASC ;

C.同时指定升序和降序

以下示例按两个列对结果集进行排序。先按 FirstName 列升序对查询结果集进行排序,然后按 LastName 列降序进行排序。

USE AdventureWorks2012;

GO

SELECT LastName, FirstName FROM Person.Person

WHERE LastName LIKE 'R%'

ORDER BY FirstName ASC, LastName DESC ;

指定排序规则

以下示例说明如何在 ORDER BY 子句中指定排序规则以更改查询结果的返回顺序。将创建一个表,其中包含一个使用不区分大小写和重音的排序规则定义的列。插入一些具有不同大小写和重音的值。由于未在 ORDER BY 子句中指定排序规则,在对值进行排序时,第一个查询将使用列排序规则。在第二个查询中,在 ORDER BY 子句中指定了区分大小写和重音的排序规则,这将改变行的返回顺序。

USE tempdb;

GO

CREATE TABLE #t1 (name nvarchar(15) COLLATE Latin1_General_CI_AI)

GO

INSERT INTO #t1 V ALUES(N'Sánchez'),(N'Sanchez'),(N'sánchez'),(N'sanchez');

-- This query uses the collation specified for the column 'name' for sorting.

SELECT name

FROM #t1

ORDER BY name;

-- This query uses the collation specified in the ORDER BY clause for sorting.

SELECT name

FROM #t1

ORDER BY name COLLATE Latin1_General_CS_AS;

指定条件顺序

以下示例在 ORDER BY 子句中使用 CASE 表达式,以根据给定的列值有条件地确定行的排序顺序。在第一个示例中,会计算 HumanResources.Employee 表中SalariedFlag 列的值。 SalariedFlag 设置为 1 的员工将按BusinessEntityID 以降序顺序返回。 SalariedFlag 设置为 0 的员工将按BusinessEntityID 以升序顺序返回。在第二个示例中,当 CountryRegionName 列等于“United States”时,结果集会按 TerritoryName 列排序,对于所有其他行则按 CountryRegionName 排序。

SELECT BusinessEntityID, SalariedFlag

FROM HumanResources.Employee

ORDER BY CASE SalariedFlag WHEN 1 THEN BusinessEntityID END DESC

,CASE WHEN SalariedFlag = 0 THEN BusinessEntityID END;

GO

SELECT BusinessEntityID, LastName, TerritoryName, CountryRegionName

FROM Sales.vSalesPerson

WHERE TerritoryName IS NOT NULL

ORDER BY CASE CountryRegionName WHEN 'United States' THEN TerritoryName ELSE CountryRegionName END;

by的用法总结

by的用法小结: 1、介词prep. 在…旁;靠近 · Our teacher was sitting by the window. 我们的老师正坐在窗户旁边。 · Stand by me! 站到我的身旁来! · We spent our holiday by the sea. 我们在海边度假。 2、介词prep. 经过 · He walked by me without speaking. 他走过我的身旁,没有说话。 · My brother goes by the building every day. 我弟弟每天从这楼旁走过。 3、介词prep. 用;靠;通过 using (showing who or what did something) · I know it by heart. 我把它记在心头。 · They can read by touch. 他们可以通过手摸来阅读。 · By getting up early, I can have an hour for reading English in the morning. 靠起得早,我每天早晨有一小时时间阅读英语。 4、介词prep. 不迟于 not later than · I shall be back by 5 o'clock. 最迟五点我一定回来。 · How many English parties had you had by the end of last term? 到上学期末,你们举行了几次英语晚会? 5、介词prep. 通过;沿着 through; along; over

· We came through the fields, not by the road. 我们是穿过田野而不是沿那条路来的。· to send a letter by post 通过邮局寄信 6、介词prep. (表示作者)被;由 word that shows the author, painter, etc. · Thirty divided by two is fifteen. 三十除以二得十五。 · The child was saved by a PLA man. 这孩子是由一位解放军战士救活的。 · This bridge was built by the soldiers. 这座桥是士兵们造的。 7、介词prep. (指交通等)乘;用 word that shows what kind of transport, etc. · The man came by bus. 那人是坐公共汽车来的。 · They went to Shanghai by air. 他们坐飞机去上海。 8、介词prep. 在…情况下;在…时间during · Do you prefer travelling by day or by night? 你喜欢在白天还是在夜晚旅行? 9、介词prep. (表示部分)在…部位word that shows which part · She led the child by the hand. 她拉着孩子的手往前走。 10、副词adv. 在旁边

order的过去式

order的过去式 那么你知道order的过去式怎么写吗?下面是为你整理的order的过去式,希望大家喜欢!order的过去式过去式:orderedorder的过去式ordered造句1. He ordered them to stack up pillows behind his back.他命令他们把几个枕头叠放在自己的背后。 2. President Garcia has ordered an airlift of food, medicines and blankets.加西亚总统已经下令空运食品、药物和毛毯。 3. The president ordered a review of US economic aid to Jordan.总统下令对美国向约旦提供的经济援助进行审查。 4. The government ordered an independent inquiry into the affair.政府下令对该事件进行独立调查。 5. Felicity Maxwell stood by the bar and ordered a glass of wine.费利西蒂·马克斯韦尔站在吧台旁,要了一杯红酒。 6. He watched the barman prepare the beer he had ordered.他看着酒吧招待员备好他点的啤酒。 7. The colonel ordered, "I want two good engines down here asap."上校命令道:“尽快给我找两台性能好的发动机来。 8. Magistrates ordered his dog Samson to be put down immediately.治安官们勒令立即将他的狗萨姆森杀掉。 9. He was given a conditional discharge and ordered to pay compensation.他被有条件地释放了,被责令支付赔偿款。

英语 花费 四种用法的区别

spend的主语必须是人,常用于以下结构: (1)sb. spend time /money on sth. 在……上花费时间(金钱)。 (2) sb.spend time / money (in) doing sth.花费时间(金钱)做某事。 例:I spent fifty yuan on the coat. = I spent fifty yuan (in) buying the coat. 我花50元买了这件大衣。 He spent three days on the work. = He spend three days (in) doing the work. 我干这项工作用了3天。 (3). spend money for sth. 花钱买 例如: His money was spent for books. 他的钱用来买书了。 cost的主语是物或某种活动,还可以表示"值",常见用法如下: (1)sth. costs (sb.) +金钱,某物花了(某人)多少钱。 例:A new computer costs a lot of money. 买一台新电脑要花一大笔钱。 (2) (doing) sth. costs (sb.) +时间,某物(做某事)花了(某人)多少时间。 例:Remembering these new words cost him a lot of time. 他花了大量时间才记住了这些单词。 注意:cost的过去式及过去分词都是cost,并且不能用于被动句。 take后面常跟双宾语,常见用法有以下几种: (1) It takes sb. +时间+to do sth. 做某事花了某人多少时间。 例:It took them three years to build this road. 他们用了三年时间修完了这条路。 (2)doing sth. takes sb. +时间,做某事花了某人多少时间。 例:Repairing this car took him the whole afternoon. 他花了一下午修车。 pay的基本用法是: (1) pay (sb.) money for sth. 付钱(给某人)买……。 例:I have to pay them 20 pounds for this room each month. 我每个月要付20英磅的房租。 (2)pay for sth. 付……的钱。 例:I have to pay for the book lost. 我不得不赔丢失的书款。 (3)pay for sb.替某人付钱。 例:Don‘t worry!I'll pay for you. 别担心,我会给你付钱的。 (4)pay sb.付钱给某人。 例: They pay us every month.他们每月给我们报酬。 (5)pay money back 还钱。(6)pay off one's money还清钱。 例:May I borrow 12 yuan from you? I'll pay it back next week. 你能借给我12块钱吗?下周还你。

(完整版)by的用法总结.doc

by 的用法小: 1、介prep. 在?旁;靠近 ·Our teacher was sitting by the window. 我的老正坐在窗旁。 ·Stand by me! 站到我的身旁来! ·We spent our holiday by the sea. 我在海度假。 2、介prep. ·He walked by me without speaking. 他走我的身旁,没有。 ·My brother goes by the building every day. 我弟弟每天从楼旁走。 3、介prep. 用;靠;通 using (showing who or what did something) ·I know it by heart. 我把它在心。 ·They can read by touch. 他可以通手摸来。 ·By getting up early, I can have an hour for reading English in the morning. 靠起得早,我每天早晨有一小英。 4、介prep. 不于 not later than ·I shall be back by 5 o'clock. 最五点我一定回来。 ·How many English parties had you had by the end of last term? 到上学期末,你行了几次英晚会? 5、介prep. 通;沿着 through; along; over ·We came through the fields, not by the road. 我是穿田野而不是沿那条路来的。 ·to send a letter by post 通局寄信 6、介prep. (表示作者)被;由

in order to 的用法

in order to [观察] 1. He got up very early in order to / so as to catch the first bus. 2. In order to catch the first bus, he got up very early. 3. He works very hard in order to / so as to support his family. 4. Turn the volume down in order not to / so as not to wake the child. [归纳] in order to 意为“为了……”,表示目的;在用法和意义上相当于so as to 结构,但是in order to结构可以用于句首、句中,而so as to多用于句中。其否定式分别为:in order not to 和so as not to。 [拓展] in order to和so as to在句中表示目的时,常可以转化成in order that或so that引导的目的状语从句。如: We should work hard in order to / so as to pass the exam. → We should work hard in order that / so that we can pass the exam. 为了能通过考试,我们应该努力学习。 [小试] 翻译下面的句子。 1. He went there early so as to / in order to get a good seat. He went there early so that / in order that he could get a good seat. 2. In order not to wake the baby we went in quietly. Key: 1. 他去得早,以便找到个好座位。 2. 为了不惊醒小孩,我们轻轻地走了进去。

四种花费和四种提供的用法

英语中“花费”的四种用法王朝红的工作室英语花费四种用法 spend的主语通常是人,往往用于以下句型: 1. (sb) spend some money/some time on sth。 2. (sb)spend some money/some time(in)doing sth。 例如: I spent fifty yuan on the coat。 = I spent fifty yuan (in) buying the coat. 我花50元买了这件大衣。 He spent three days on the work. = He spend three days (in) doing the work. 我干这项工作用了3天。 3.spend money for sth. 花钱买……。 例如:His money was spent for books. 他的钱用来买书了。 take常用于“占用、花费”时间,后面常跟双宾语,其主语通常为形式主语“it”或物。句式是: 1. It takes/took sb.some time to do sth 例如:It will take me two days to do the work. 这项工作花了2天时间。 2. Doing sth./Sth.takes sb.some time. 例如: The work will take me two days。这项工作花了2天时间。

Repairing this car took him the whole afternoon. 他花了一下午修车。 It took me three years to draw the beautiful horses。 =Drawing the beautiful horses took me three years。 画这些漂亮的马花费了我3年时间。 pay为“付款、赔偿”之意,主语通常是人,句型 1. sb. pays some money for sth 例如: I paid fifty yuan for the coat。我花50元买了这件大衣。 2. pay (sb。) money for sth. 付钱(给某人)买……。 例如:I have to pay them 20 pounds for this room each month. 我每个月要付20英磅的房租。 3. pay money back 还钱。 例如:May I borrow 12 yuan from you? I'll pay it back next week. 你能借给我12块钱吗?下周还你。 4. pay off one's money 还清钱。 cost的主语是物或某种活动,还可以表示“值”。句型 1. sth. costs (sb。) +money, 某物花了(某人)多少钱。

by用法的练习题

by用法的练习题 1. Come and sit _______ (我旁边). 2. There is a big tree _______ (在河边). 3. _______________ (到上星期日)I had finished the book . 4. Can you finish the work _____ (在五点之前). 5. Her mother goes to work ____ bus every morning. A.by B.at C.take D.o n 6.She came home _________ (乘飞机). 7.Did you make the desk ___________ (自己独自)? 8.She made a meal for her parents __________ (独自)for the first time. 9. _______________ (顺便问一下)how many people are there in your family? 10. You should know her ______________ (逐渐地). 11.Ice has been turned into water ___________ (受热). 12. ________________ (不久以后)more and more people bega n to study En glish . 13. he Great Wall was built ____________ (用手). 14. He makes a livi ng _________________ (通过教书). 15. -How do you lear n En glish? -I learn English ________________________ (通过向老师请教的方式). used to相关用法的练习题 一、翻译 1. 我妈妈习惯早起。 2. 王先生曾经是一位工人。 3. 他过去常常骑自行车上学。 二、用所给单词的适当形式填空: 1. We used to _ (go )swimming last year. 2.1 am used to ___ (run)every morning. 3. Bamboos are used to _(build) houses there. 4. They have bee n used to ___ (live ) in the coun tryside. 三、根据汉语意思完成句子: 1.1 ___________________ the food here.(我习惯于吃这儿的食物。)

“四个花费”spend,cost,take, pay讲解及对应中考练习

“四个花费”讲解及对应中考练习 spend,cost,take, pay spend,cost,take和pay的区别是历年考试的必考内容之一,虽然它们都可以表示"花费",但用法却不尽相同,讲解如下: spend的主语必须是人,常用于以下结构: (1) spend time /money on sth. 在……上花费时间(金钱)。 例:I spent two hours on this maths problem. 这道数学题花了我两个小时。 (2) spend time /money (in) doing sth. 花费时间(金钱)做某事。 例:They spent two years (in) building this bridge. 造这座桥花了他们两年时间。 (3)spend money for sth. 花钱买……。 例:His money was spent for books. 他的钱用来买书了。 cost的主语是物或某种活动,还可以表示"值",常见用法如下: (1)sth. costs (sb.) +金钱,某物花了(某人)多少钱。 例:A new computer costs a lot of money. 买一台新电脑要花一大笔钱。 (2) (doing) sth. costs (sb.) +时间,某物(做某事)花了(某人)多少时间。 例:Remembering these new words cost him a lot of time. 他花了大量时间才记住了这些单词。 注意:cost的过去式及过去分词都是cost,并且不能用于被动句。 take后面常跟双宾语,常见用法有以下几种: (1) It takes sb. +时间+to do sth. 做某事花了某人多少时间。 例:It took them three years to build this road. 他们用了三年时间修完了这条路。 (2)doing sth. takes sb. +时间,做某事花了某人多少时间。 例:Repairing this car took him the whole afternoon. 他花了一下午修车。 pay的基本用法是: (1) pay (sb.) money for sth. 付钱(给某人)买……。 例:I have to pay them 20 pounds for this room each month. 我每个月要付20英磅的房租。 (2)pay for sth. 付……的钱。 例:I have to pay for the book lost. 我不得不赔丢失的书款。 (3)pay for sb. 替某人付钱。 例:Don‘t worry!I'll pay for you. 别担心,我会给你付钱的。 (4)pay sb. 付钱给某人。 例: They pay us every month.他们每月给我们报酬。 (5)pay money back 还钱。 例:May I borrow 12 yuan from you? I'll pay it back next week. 你能借给我12块钱吗?下周还你。 (6)pay off one's money还清钱。 【真题对应练习】 1.(广州某校2015期中)--- How much does your new bike ___________ ?

介词by用法归纳-九年级

页脚.

. . 教学过程 一、课堂导入 本堂知识是初中最常见的介词by的一个整理与总结,让学生对这个词的用法有一个系统的认识。页脚.

. . 二、复习预习 复习上一单元的知识点之后,以达到复习的效果。然后给学生一些相关的单选或其他类型题目,再老师没有讲解的情况下,让学生独立思考,给出答案与解释,促进学生发现问题,同时老师也能发现学生的盲点,并能有针对性地进行后面的讲课。 页脚.

. . 三、知识讲解 知识点1: by + v.-ing结构是一个重点,该结构意思是“通过……,以……的方式”,后面常接v.-ing形式,表示“通过某种方式得到某种结果”,即表示行为的方式或手段。 I practice speaking English by joining an English-language club. 我通过加入一个英语语言俱乐部来练习讲英语。 Mr Li makes a living by driving taxis.先生靠开出租车为生。 页脚.

. . 页脚. 介词by + v.-ing 结构常用来回答How do you...?或How can I...?之类的问题。 —How do you learn English? 你怎样学习英语呢? —I learn English by reading aloud. 我通过大声朗读来学英语。 —How can I turn on the computer? 我怎样才能打开电脑呢? —By pressing this button. 按这个按钮。 知识点2:by 是个常用介词,其他用法还有: 1【考查点】表示位置,意思是“在……旁边”,“靠近……”,有时可与beside互换。 The girls are playing by (beside) the lake. 女孩们正在湖边玩。 此时要注意它与介词near有所不同,即by 表示的距离更“近”。比较: He lives by the sea. 他住在海滨。 He lives near the sea. 他住在离海不远处。

SQL中order by 、group by 、having的用法区别

order by 、group by 、having的用法区别 order by 从英文里理解就是行的排序方式,默认的为升序。order by 后面必须列出排序的字段名,可以是多个字段名。 group by 从英文里理解就是分组。必须有“聚合函数”来配合才能使用,使用时至少需要一个分组标志字段。 什么是“聚合函数”? 像sum()、count()、avg()等都是“聚合函数” 使用group by 的目的就是要将数据分类汇总。 一般如: select 单位名称,count(职工id),sum(职工工资) form [某表] group by 单位名称 这样的运行结果就是以“单位名称”为分类标志统计各单位的职工人数和工资总额。 在sql命令格式使用的先后顺序上,group by 先于order by。select 命令的标准格式如下: SELECT select_list [ INTO new_table ] FROM table_source [ WHERE search_condition ] [ GROUP BY group_by_expression ] [ HA VING search_condition ] 1. GROUP BY 是分组查询, 一般GROUP BY 是和聚合函数配合使

用 group by 有一个原则,就是select 后面的所有列中,没有使用聚合函数的列,必须出现在group by 后面(重要) 例如,有如下数据库表: A B 1 abc 1 bcd 1 asdfg 如果有如下查询语句(该语句是错误的,原因见前面的原则)select A,B from table group by A 该查询语句的意图是想得到如下结果(当然只是一相情愿) A B abc 1 bcd asdfg 右边3条如何变成一条,所以需要用到聚合函数,如下(下面是正确的写法): select A,count(B) as 数量from table group by A 这样的结果就是 A 数量 1 3 2. Having

by用法的练习题

by用法的练习题 by用法的练习题 https://www.doczj.com/doc/5d8336622.html,e and sit ____ (我旁边). 2.There is a big tree (在河边). 3. (到上星期日)I had finished the book. 4.Can you finish the work (在五点之前). 5.Her mother goes to work bus every morning. A.by B.at C.take D.on 6.She came home _____ (乘飞机). 7.Did you make the desk (自己独自)? 8.She made a meal for her parents (独自)for the first time. 9. (顺便问一下)how many people are there in your family? 10.You should know her (逐渐地). 11.Ice has been turned into water (受热). 12. (不久以后)more and more people began to study English . 13.he Great Wall was built (用手). 14. He makes a living (通过教书). 15.-How do you learn English? -I learn English (通过向老师请教的方式). used to 相关用法的练习题 一、翻译 1.我妈妈习惯早起。 2.王先生曾经是一位工人。 3.他过去常常骑自行车上学。 二、用所给单词的适当形式填空: 1.We used to ___ (go )swimming last year. 2.I am used to ____(run)every morning. 3.Bamboos are used to ___(build) houses there. 4.They have been used to ______(live ) in the countryside. 三、根据汉语意思完成句子: 1.I _________________the food here.(我习惯于吃这儿的食物。) 2.Tom_____________here.(汤姆曾在这儿住过。) 3.I ___________in the river when I was a child.(我小时候常常去河里游泳。) 4.Wood _____________paper. (木头可以用来造纸。) 1.Chinese people keep pig for food , but now some people keep them as pets. https://www.doczj.com/doc/5d8336622.html,ed to B.has to C had better 2. 1 / 1

四种花费和四种提供的用法

四种花费和四种提供的 用法 公司内部编号:(GOOD-TMMT-MMUT-UUPTY-UUYY-DTTI-

英语中“花费”的四种用法王朝红的工作室英语花费四种用法 spend的主语通常是人,往往用于以下句型: 1. (sb) spend some money/some time on sth。 2. (sb)spend some money/some time(in)doing sth。 例如: I spent fifty yuan on the coat。 = I spent fifty yuan (in) buying the coat. 我花50元买了这件大衣。 He spent three days on the work. = He spend three days (in) doing the work. 我干这项工作用了3天。 3.spend money for sth. 花钱买……。 例如:His money was spent for books. 他的钱用来买书了。 take常用于“占用、花费”时间,后面常跟双宾语,其主语通常为形式主语“it”或物。句式是: 1. It takes/took sb.some time to do sth

例如:It will take me two days to do the work. 这项工作花 了2天时间。 2. Doing sth./Sth.takes sb.some time. 例如: The work will take me two days。这项工作花了2天时间。 Repairing this car took him the whole afternoon. 他花了一下午修车。 It took me three years to draw the beautiful horses。 =Drawing the beautiful horses took me three years。 画这些漂亮的马花费了我3年时间。 pay为“付款、赔偿”之意,主语通常是人,句型 1. sb. pays some money for sth 例如: I paid fifty yuan for the coat。我花50元买了这件大衣。 2. pay (sb。) money for sth. 付钱(给某人)买……。 例如:I have to pay them 20 pounds for this room each month.我每个月要付20英磅的房租。

in order to用法

in order to可以用在句首或句末,但so as to只能用在句末。 如: He got up very early in order to/so as to catch the first bus. In order to catch the first bus,he got up very early.(此时不能用so as to)so as to 和in order to的汉语意思应该是一样的“为的是,为了”。它们的英语功能也是一样的,都可以用来引导目的状语。它们的不同之处就在于so as to 不能用于句子的开头,在句子开头只能用in order to. 另外, 1.in order to 一般用in order that加从句来替换;而so as to 一般用so that加从句来替换。in order that 可以在句首,so that和so as to 一样不能在句首。 2.当这两个短语后的不定式动词的逻辑主语和句子的主语一致时,“in order to , so as to +不定式”可以简化为“不定式” In order to get to school on time,he got up earlier.这个句子可以表达为下列几种方式:In order that he could get to school on time,.... He got up earlier in order to get to school on time. He got up earlier in order that he could get to school on time. He got up earlier so as to get to school on time. He got up earlier so that he could get to school on time. To get to school on time, he got up earlier. (这种不定式有时可以表示目的以外的状语) 1.so that表目的。在非正式语体中,so可以代替so that,引出目的状语从句。例如:He is going to the lecture early so (that) he will get a good seat. 2.so that表结果。so是so that 的省略形式,引导结果状语从句,主要用在口语中。 3.in order that与虚拟式 They removed the prisoner in order that he not disturb the procceedings any f urther.句子中he not disturb符合语法吗?是否应该改成he does not disturb? 在正式语体中,in order that引导的状语从句有时也采用现在虚拟式,上句中的he not disturb也可以用he should not disturb来替换。 4.in order that与情态动词 在in order that从句中可以使用can,could,may,might,should,would等情态动词。 5.in order to in order to+动词不定式用来表目的,它所引导的是目的状语。 6.so that与in order that的关系 in order that用于相当正式的语体中,表示经过精心策划的目的,有时可与so t hat互换。

四种花费用法讲解

Take\spend\pay\cost表示花费的时候用法1、It takes sb some time to do sth. 该句型只表示花费时间,it是形式主语,真正的主语是动词不定式。sb是宾格形式,some time 是一段时间。 Eg: a.It took the boys two weeks to plant the trees last spring. b.It takes me ten minutes to walk to school every day. c.It will take us about 30 minutes to finish listening the story. 2. Sb spends some time/money (in) doing sth. Sb spends some time/money on sth. 该句型可表示花费时间,也可以表示花费金钱。主语必定是人,做某事可以用动词表示,也可用名词表示。 d.We spent the whole day going hiking in Mount Tai last summer. e.Did you spend ten yuan on the pen? f.All the boys spent about five minutes

remembering the ten English words. 除此之外,还有pay和cost也可以表示花费金钱。 Pay 常用for连用,构成pay for 意思是赔尝、付款。主语必须是人。 I paid for the book yesterday. 昨天我买了这本书。 I paid ten yuan for the book yesterday. 昨天我花了十元钱买了这本书。 You should pay for the book if you lose it. 如果你丢了这本书,你就应该赔偿。 Cost 表示值多少钱,也表示花费。 The magazine costs twenty yuan. The bicycle cost me eight hundred and fifty yuan.

by的用法小结

by的用法小结 1.用于被动语态的句子中,表示动作的执行者,意为“被;由”。 He was praised by the teacher.他受到了老师的表扬。 The book was written by Lu Xun.这本书是鲁迅写的。 2.表示方式、方法、手段等,后常接无冠词的名词或动名词,意为“通过;靠;用”。 Don't judge a person by appearances. 勿以貌取人。 He made a living by teaching.他以教书为生。 3.表示时间,意为“到……时(为止”或“不迟于……”。 He ought to be here by now.他现在应该在这儿了。 By the time he was ten, he had learnt about 1,000 English words.到十岁时,他已学了约一千个英语单词。 4.表示(增减)程度,尺寸数量等,意为“至……的程度”。 the bullet missed me by two inches.那子弹以两英寸之差未击中我。 the rope needs to be longer by two feet.这绳子需要再长两英尺。 5.表示交通路线或工具,后接名词不用冠词,意为“乘;坐”。 go by bus / plane / train 乘汽车(飞机、火车)去 travel by land / sea / air 陆上(海上、空中)旅行 6.表示位置,意为“在近旁;在……旁边”。 There is a pumping station by the river.河边有个抽水站。

so that和in order that等 用法区别

so that和in order that I hurried _____ I wouldn't be late for class.这里为什么用so that不用in order that?麻烦详细解析,谢谢! 你好,这里要用so that因为固定词组是in order to,如果用in order that本身词组有问题了,可以查一查词组字典所以可以说I hurried in order to not be late for class,这样才对。你只要记牢so that后面跟的是一个长句子,而in order to 后面跟的是一个短语,这道题很明显空格后面是一个长句子,自然要用so that 了 2、so that:有两种用法——①【为的是,以便】,引导目的状语从句,此时意义上等同于in order that。但是,区别在于【in order that】可以【放在句首】,而【so that】则【不能放在句首】。例如:We started early 【so that/in order that 】we could get the first bus.【In order that】the workers can work hard,they have been given higher bonus.2.【以至于;结果】,引导【结果状语从句】,一般【用逗号与主句隔开】。例如:They ran to the station, 【so that】they caught the train for Beijing in time. 3、so...that,【以至于;结果】,引导【结果状语从句】。例如:Li Lei studied【so 】hard 【that】he was admitted into Fudan University last year. 4、in order to,so as to 这两个短语都是【以便;为了】,表示目的,但是,他们都是【不定式】形式,不能引导从句。还有,在位置上,【so as to】【不能位于句首】;而【in order to】则【可以放在句首】。例如:A large number of college students prefer to working 【in order to/so as to】make money for their education. 【In order to】help great numbers of senior students realise their dreams of going to college, our government have taken lots of measures . so that、in order that、so as 、in order to 各自的用途与它们之间的区别 so that 是以至于的意思,他和so ...that也不一样,(省略出是个形容词)1.so that表目的。在非正式语体中,so可以代替so that,引出目的状语从句。例如:He is going to the lecture early so (that) he will get a good seat. 2.so that表结果。so是so that 的省略形式,引导结果状语从句,主要用在口语中。 3.in order that与虚拟式They removed the prisoner in order that he not disturb the procceedings any further.句子中he not disturb符合语法吗?是否应该改成he does not disturb? 在正式语体中,in order that引导的状语从句有时也采用现在虚拟式,上句中的he not disturb也可以用he should not disturb来替换。4.in order that与情态动词在in order that从句中可以使用can,could,may,might,should,would等情态动词。5.in order to in order to+动词不定式用来表目的,它所引导的是目的状语。6.so that与in order that的关系in order that 用于相当正式的语体中,表示经过精心策划的目的,有时可与so that互换。7。so as和to 搭配。构成固定搭配so as to ,它和in order to 的意思是一样的,没有什么具体的区别 so that与so ... that ...的用法在近几年来全国各省市的中考试题中出现率较高,一直是历年来中考试题的重要考点。下面结合近几年来的中考试题,将so that与so ... that ... 的用法归纳如下: 一、so that引导目的状语从句时,表示“以便;为了”,从句中常使用can /could /may /might /will /would /should等情态动词或助动词;引导结果状语从句时,从句中一般不用can和may 等词,在so that前可以用逗号,意思是“因此;所以”。如: 1. The little boy saved every coin_________ __________he could buy his mother a present on Mother's day.(用所给的短语填空,每个短语只能用一次)(2003大连市) (答案为so that。)

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