1.1 This chapter describes some of the major advantages of the database system. What it has two shortcomings?
Establish a database system requires more knowledge and skills, as well as more time and money
database complexity of the system may result in poor performance
1.2 List language like Java or C ++ type description in the data definition language (DDL) system and the database system using five different from
a DDL will add a specific implementation in a database; contrast, execution type Description language is only a simple statement of abstract object
database DDL matter must meet the definition of consistency, include domain constraints, and referential integrity constraints; and the need to maintain consistency type Description language
DDL support authorization for administering different for different authority; and type description language does not support direct authorization
type description language richer than many types of DDL. Most databases support only a few basic types and strings, some will support the array and object types
DDL focus on the relationship between attributes, and Type Description Language focuses on object creation and manipulation
1.3 lists six major steps to establish a database for the enterprise
comprehensive characterization data requirements database users, develop user requirements specification document
conceptual design: data describing the relationship between them and
the logical design phase: the conceptual model is mapped to the data model on the development of the data attribute constraints between
the physical design phase: the specified database particle characteristics, including the form of file organization, and the interior of the storage structure
for the function required by the user, such as CRUD etc., to develop and implement their corresponding interface
1.4 In addition to section 1.6.2 already listed, please list the university to be maintained in at least three different types of information
the school maintains a list of published papers, details include: title, journal name, first author, Corresponding author
study published in various journals, including: Journal name, the year before IF, last IF, this year IF, nearly three years IF, the number of published papers.
Published papers by various authors, including: name of the author, published several articles, the total number of citations, H factor, belongs faculties
1.5 If you want to build a similar YouTube video node, and consider the various shortcomings of the data listed in Section 1.2 are stored in the file system, and discuss each one drawback with the actual storage of video data and metadata about the video (such as a title upload to its users, tags, viewing its users) associated
storage method: a file storage video ID, video title, video content, video upload time duration of a video, the uploader; file 2 for storing video corresponding number tag; 3 stores the video file numbers corresponding to the user viewing it; evaluation 4 stores the video file corresponding number
of redundant and inconsistent data: correlation of video data in a small site, and update the same properties involving less plurality of tables, Therefore disadvantages less affected
data access difficulties: complex search conditions difficult to meet the
data in isolation: the "data redundancy and inconsistent", was less affected
integrity problem: fewer cases of data video sites need to be constrained, and therefore little effect
atomicity problem: when the video update time corresponding to the video, and other information required duration When updating, loss of atomicity, the video may not be consistent with their attribute information
concurrent access exceptions: video information is rarely updated multiple users, it is less affected
security issues: ordinary users can not modify the video content, video upload and Webmasters it can, it will affect