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dbms_排名前50位的DBMS面试问答

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1) What are the drawbacks of the file system which is overcome on the database management system?

1)在數(shù)據(jù)庫管理系統(tǒng)上克服的文件系統(tǒng)有哪些缺點？

Ans: Data redundancy & isolation, difficulty in accessing data, data isolation, and integrity problem these are drawbacks of the file system.

答案：數(shù)據(jù)冗余和隔離，訪問數(shù)據(jù)困難，數(shù)據(jù)隔離以及完整性問題是文件系統(tǒng)的缺點。

2) What is database system?

2)什么是數(shù)據(jù)庫系統(tǒng)？

Ans: The database which is the collection of information and DBMS software together is called database system.

回答：作為信息和DBMS軟件的集合的數(shù)據(jù)庫稱為數(shù)據(jù)庫系統(tǒng)。

3) Which level of abstraction describes what data are stored in the database?

3)哪個抽象級別描述了數(shù)據(jù)庫中存儲了哪些數(shù)據(jù)？

Ans: Logical level describes what data are stored in the database.

回答：邏輯級別描述了哪些數(shù)據(jù)存儲在數(shù)據(jù)庫中。

4) What is view level or external level data hiding?

4)什么是視圖級別或外部級別數(shù)據(jù)隱藏？

Ans: It is the highest level of abstraction that describes only part of the entire database this part implies the interaction of users with the system.

回答：它是最高的抽象級別，僅描述了整個數(shù)據(jù)庫的一部分，這部分意味著用戶與系統(tǒng)的交互。

5) Why is the entity set called weak entity set?

5)為什么將實體集稱為弱實體集？

Ans: The entity set is called weak entity set because it does not have the primary key.

回答：實體集稱為弱實體集，因為它沒有主鍵。

6) What are the extended features of ER diagram?

6)ER圖的擴展功能是什么？

Ans: Specialization, generalization, aggregation are the extended features of ER diagram.

回答：專業(yè)化，通用化，聚合是ER圖的擴展功能。

7) How many types of relationship exist in database designing?

7)數(shù)據(jù)庫設(shè)計中存在幾種類型的關(guān)系？

Ans: There are three major relationship models,

答：有三種主要的關(guān)系模型，

One- to- one

一對一

One- to- many

一對多

Many- to- many

多對多

8) What is the minimum cardinality of zero specifies?

8)零的最小基數(shù)是多少？

Ans: Partial participation is the minimum cardinality of zero specifies.

回答：部分參與是指定的最小基數(shù)為零。

9) When the fan trap may exist in ER model.

9)ER模型中可能存在風扇陷阱。

Ans: When two or more one to more relationships fan out from the same entity set then the fan trap may exist in ER model.

回答：當兩個或多個一對一關(guān)系從同一實體集中散開時，則扇形陷阱可能存在于ER模型中。

10) What is RAT axioms in DBMS?

10)DBMS中的RAT公理是什么？

Reflexivity, argumentation, transitivity these are the Armstrong rule which is sufficient enough to find closure set.

自反性，論據(jù)，傳遞性是阿姆斯特朗規(guī)則，足以找到閉合集。

11) What are database languages?

11)什么是數(shù)據(jù)庫語言？

Ans: These are the special purpose languages in DBMS. It is of three types of DDL (data definition language), DML (data manipulation language, a query language.

回答：這些是DBMS中的專用語言。它具有DDL(數(shù)據(jù)定義語言)，DML(數(shù)據(jù)操作語言，查詢語言)三種類型。

12) What is meant by index cardinality?

12)索引基數(shù)是什么意思？

Ans: Index cardinality is the total number of distinct key values for each index.

答案：索引基數(shù)是每個索引的不同鍵值的總數(shù)。

13) What is the foreign key?

13)什么是外鍵？

The attribute of one table which is referencing the primary key of other table is called foreign key.

一個表的屬性引用另一個表的主鍵稱為外鍵。

14) What is prime attribute of the relational schema?

14)關(guān)系模式的主要屬性是什么？

Ans: An attribute is called prime attribute when it is the part of any candidate key in the relational schema.

回答：當屬性是關(guān)系模式中任何候選鍵的一部分時，該屬性稱為主要屬性。

15) How many types of normal form in normalization?

15)規(guī)范化中有幾種類型的規(guī)范形式？

There are mainly four types of normal form,

范式主要有四種類型，

1 NF (first normal form)

1 NF(第一個范式)

2 NF (second normal form)

2 NF(第二范式)

3 NF (third normal form)

3 NF(第三范式)

BCNF (Boyee-Codd normal form)

BCNF(Boyee-Codd正常形式)

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16) What is the full form of PGNF?

16)PGNF的完整形式是什么？

The full form of PGNF has projected join normal form it is the 5 the normal form and it cannot have a lossless decomposition into any number of smaller tables.

PGNF的完整形式已預測聯(lián)接普通形式，它是普通形式的5，并且不能無損地分解成任意數(shù)量的較小表。

17) What is RDBMS?

17)什么是RDBMS？

Relational database management system (RDBMS) is the database management system that maintains data records and indices in tables

關(guān)系數(shù)據(jù)庫管理系統(tǒng)(RDBMS)是一種數(shù)據(jù)庫管理系統(tǒng)，用于維護表中的數(shù)據(jù)記錄和索引

18) What is chasm trap?

18)什么是陷阱？

Ans: When the two relations are interconnected through partial participation by another relation then it is called chasm trap.

回答：當兩個關(guān)系通過另一個關(guān)系的部分參與而相互連接時，則稱為鴻溝陷阱。

19) What is a transaction in DBMS?

19)什么是DBMS中的事務(wù)？

Ans: A transaction is a logical unit of database processing that includes one or more database access operations.

回答：事務(wù)是數(shù)據(jù)庫處理的邏輯單元，包括一個或多個數(shù)據(jù)庫訪問操作。

20) Which property makes transaction consistent?

20)哪個屬性可使交易保持一致？

Ans: The transaction should possess several properties called ACID property,

回答：交易應(yīng)具有幾個稱為ACID屬性的屬性，

A- Atomicity

A-原子性

C – Consistency

C –一致性

I – isolation

我–隔離

D – Durability

D –耐久性

21) What are the different phases of the transaction?

21)交易有哪些不同階段？

Ans: There are three different phases of the transaction. Analysis phase, Redo phase, Undo phase.

回答：交易分為三個不同階段。分析階段，重做階段，撤消階段。

22) What are the Transaction states?

22)什么是交易狀態(tài)？

Ans: A transaction moves from one state to the other as it entries the system to be executed. There are many states like active, partially committed, failed, Aborted, committed.

答：事務(wù)在進入要執(zhí)行的系統(tǒng)時會從一種狀態(tài)轉(zhuǎn)移到另一種狀態(tài)。有許多狀態(tài)，例如活躍，部分承諾，失敗，中止，承諾。

23) What is concurrency?

23)什么是并發(fā)？

Ans: Concurrency is the ability of the database system to handle simultaneously a number of transactions by overlapping or interleaving parts of their actions.

回答：并發(fā)是數(shù)據(jù)庫系統(tǒng)通過重疊或交錯部分操作來同時處理多個事務(wù)的能力。

24) What is the common problem that happens due to concurrency?

24)由于并發(fā)發(fā)生的常見問題是什么？

Ans: There are many common problems,

答：有很多常見問題，

Dirty read problem
臟讀問題
Loss update problem
損失更新問題
Unrepeatable read problem
不可重復的閱讀問題
Phantom read problem
幻影讀取問題

25) What is read timestamp?

25)什么是讀取時間戳？

Ans: It is the timestamp of the transaction that has performed latest read operations.

回答：是執(zhí)行最新讀取操作的事務(wù)的時間戳。

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26) What is SQL?

26)什么是SQL？

Ans: SQL stands for (structured query language). It is a standard computer language for accessing and manipulating database systems. It is also used to retrieve and update data in a database.

回答： SQL代表(結(jié)構(gòu)化查詢語言)。它是用于訪問和操縱數(shù)據(jù)庫系統(tǒng)的標準計算機語言。它還用于檢索和更新數(shù)據(jù)庫中的數(shù)據(jù)。

27) What is scheduling?

27)什么是排程？

Ans: A schedule contains two or more transactions executed together or one after another.

回答：計劃包含兩個或多個一起執(zhí)行的事務(wù)或一個接一個地執(zhí)行。

28) How can the schedule be classified?

28)時間表如何分類？

Ans: A schedule can be classified in mainly two ways,

回答：時間表主要可以通過兩種方式分類：

On the basis of serializability

基于可序列化

On the basis of recoverability

基于可恢復性

29) What are blind writes?

29)什么是盲寫？

Ans: When the update occurs without knowing or accessing previous value of data items are called blind updation or blind writes.

回答：如果在不知道或無法訪問數(shù)據(jù)項先前值的情況下進行更新，則稱為盲更新或盲寫。

30) What are the various methods of concurrency control?

30)并發(fā)控制有哪些各種方法？

Ans: There are various concurrency control techniques like Time stamping protocol, Locked based protocol, Optimistic concurrency.

回答：有多種并發(fā)控制技術(shù)，例如時間戳協(xié)議，基于鎖定的協(xié)議，樂觀并發(fā)。

31) What is the trigger?

31)觸發(fā)因素是什么？

Ans: A trigger is a SQL procedure that initiates an action when an event (INSERT, DELETE, or UPDATE) occurs.

回答：觸發(fā)器是一個SQL過程，當事件(INSERT，DELETE或UPDATE)發(fā)生時，該觸發(fā)器將啟動操作。

32) Which level of locking provides more concurrency in a relational database?

32)哪種級別的鎖定可在關(guān)系數(shù)據(jù)庫中提供更多的并發(fā)性？

Ans: Row-level provides the highest degree of concurrency in a relational database.

回答：行級在關(guān)系數(shù)據(jù)庫中提供了最高的并發(fā)度。

33) What is VDL?

33)什么是VDL？

Ans: VDL is view definition language which specifies user’s views and their mapping to the conceptual schema.

回答： VDL是視圖定義語言，它指定用戶的視圖及其到概念架構(gòu)的映射。

34) What is a checkpoint?

34)什么是檢查站？

Ans: A checkpoint is like a snapshot of the DBMS state. By taking checkpoint the DBMS can reduce the amount of work to be done during restart.

回答：檢查點就像是DBMS狀態(tài)的快照。通過使用檢查點，DBMS可以減少重新啟動期間要完成的工作量。

35) What is Deadlock?

35)什么是死鎖？

Ans: Deadlock occurs when two transactions are each waiting on a resource that the other transaction holds.

回答：當兩個事務(wù)都在等待另一個事務(wù)所擁有的資源時，就會發(fā)生死鎖。

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36) What is the use of DBCC Command?

36)DBCC命令的用途是什么？

Ans: DBCC stands for database consistency checker. We use these commands to check the consistency of the database.

回答： DBCC代表數(shù)據(jù)庫一致性檢查器。我們使用這些命令來檢查數(shù)據(jù)庫的一致性。

37) What is Thomas write rule?

37)什么是托馬斯寫規(guī)則？

Ans: In Thomas write rule we suggest a modification in time stamping protocol when the attempt writes request.

回答：在Thomas寫規(guī)則中，我們建議在嘗試寫請求時修改時間戳協(xié)議。

38) What is the recoverable schedule?

38)什么是可恢復時間表？

Ans: A schedule is said to be recoverable if in case of failure the dependent schedule has a chance of rollback.

回答：如果從屬日程表有回退的機會，則日程表可以恢復。

39) What is cascading rollback?

39)什么是級聯(lián)回滾？

Ans: It is the phenomenon in which a single transaction failure leads to a series of transaction rollbacks it is called cascading rollback.

回答：這種現(xiàn)象是單個事務(wù)失敗導致一系列事務(wù)回滾，稱為級聯(lián)回滾。

40) What are instances?

40)什么是實例？

Ans: The collection of information stored in the database at a particular moment is called instances.

回答：在特定時刻存儲在數(shù)據(jù)庫中的信息集合稱為實例。

41) In which fields the clustered index is built?

41)聚集索引在哪些字段中構(gòu)建？

Ans: A clustered index is built on the Ordering non-key field.

回答：聚集索引建立在“訂購非關(guān)鍵”字段上。

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42) Why the DBMS uses B and B+ trees for searching?

42)為什么DBMS使用B和B +樹進行搜索？

Ans: B and B+ tree keep the height of the tree smaller thus reduce searching time. These trees grow horizontally while other AVL, Red black trees grow vertically.

答案： B和B +樹使樹的高度變小，從而減少了搜索時間。這些樹水平生長，而其他AVL，紅黑樹垂直生長。

43) Why are B+ trees preferred over B tree?

43)為什么B +樹比B樹更受青睞？

Ans: The B+ tree is suitable for sequential and direct access. B+ tree height is less than that of B tree and all leaf nodes are at same level.

答案： B +樹適用于順序訪問和直接訪問。 B +樹的高度小于B樹的高度，并且所有葉節(jié)點處于同一水平。

44) What is view?

44)什么是視圖？

Ans: A view may be a subset of a database or it may contain virtual data that is stored in the database files but is not explicitly stored.

回答：視圖可能是數(shù)據(jù)庫的子集，或者它可能包含存儲在數(shù)據(jù)庫文件中但未明確存儲的虛擬數(shù)據(jù)。

45) What are important pieces of RDBMS architecture?

45)RDBMS體系結(jié)構(gòu)的重要部分是什么？

Ans: There are two important pieces of RDBMS first is kernel which is the software and other is data directory which consists of system level data structure.

回答： RDBMS有兩個重要的部分，首先是內(nèi)核，這是軟件，而另一個是數(shù)據(jù)目錄，它由系統(tǒng)級數(shù)據(jù)結(jié)構(gòu)組成。

46) How can we communicate with an RDBMS?

46)我們?nèi)绾闻cRDBMS通信？

Ans: We can communicate with an RDBMS using SQL (structured query language).

回答：我們可以使用SQL(結(jié)構(gòu)化查詢語言)與RDBMS進行通信。

47) What is a catalog?

47)什么是目錄？

Ans: A catalog is a table that consists the information such as the structure of each file, type, and storage format for each data item. The information stored in the catalog is called Metadata.

回答：目錄是一個表，包含諸如每個數(shù)據(jù)項的每個文件的結(jié)構(gòu)，類型和存儲格式之類的信息。目錄中存儲的信息稱為元數(shù)據(jù)。

48) What is the order of clause?

48)子句的順序是什么？

Ans: ORDER by clause helps us to sort the data by ascending order or descending order.

回答： ORDER by子句可幫助我們按升序或降序?qū)?shù)據(jù)進行排序。

49) What is Phantom read problem?

49)什么是幻影讀取問題？

Ans: In phantom read problem, a transaction cannot repeat its read instruction because that variable is deleted by some other instruction.

回答：在幻像讀取問題中，事務(wù)無法重復其讀取指令，因為該變量已被其他指令刪除。

50) What is join?

50)什么是加入？

Ans: Joins helps in explaining the relationship between different tables. There are of two types – INNER JOIN and OUTER JOIN.

答案：聯(lián)接有助于解釋不同表之間的關(guān)系。有兩種類型-INNER JOIN和OUTER JOIN。

I hope you will like these DBMS Interview questions and answers, if you feel any difficulty in any question please write in the comment box.

我希望您會喜歡這些DBMS面試問題和答案，如果您對任何問題有任何困難，請在評論框中寫下。

翻譯自: https://www.includehelp.com/dbms/top-50-dbms-interview-questions-and-answers.aspx

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