2 thoughts on “emart wholesale jewelry Cai Da VF short answer questions”

  1. wholesale alabama crimson tide jewelry Answer questions: (1 to 3 chapters)
    1, what is data? What is information? What is the relationship between the two?
    : Data (data) is a symbol set used to record or mark physical things. Including text, images, graphics, value, characters, etc., it contains two aspects: one is the data content describing the characteristics of things; the other is the data type.
    In information () is valuable data formed after processing.
    The relationship between the two is: data is the basis of information, information is the result of data processing, effective data can process useful information, and useful information can guide people to make scientific predictions and decisions.

    2, what are the main characteristics of the database system?
    : The database system is a computer system that guides the database technology. It is an organized and dynamic data set. Its main characteristics are:
    (1) Realize data sharing to reduce data redundancy;
    (2) data independence;
    (3) use specific data models;
    (4) Unified management and control;

    3, what functions and functions of the project manager are?
    : The project manager is the main organization tool for processing data and objects, and is the control center of VFP. It integrates some related files, data, documents, etc., and manages it with graphics and classification. Visual FoxPro projects are stored in files with .pjx as an extension. Its functions and functions are:
    (1) Double -click the application component (form, menu, program) to modify it; (2), tables, or fields can be dragged directly from the "project manager" into " Form designer "or" class designer ";
    (3) can be dragged between class libraries;
    (4) can be easily viewed and modified its own table;
    (((((((((
    5) Can be dragged and dropped between the projects;
    4, briefly describe the writing format of the VFP command and the writing rules of the command?
    : The writing format of the vfp command: command verb [from u003Csource file>] [to u003Ctarget file>] [record range] [for/while u003Ccondition>] n Writing rules of commands
    (1) Start with command verbs;
    (2) separate spaces between parts;
    (3) commands, clauses, function names Can be briefed as the first four characters, large, lowercase equivalent;
    (4) A line can only write one command, the total length does not exceed 8192 characters, and the continuation symbol is used when the width is exceeded. n (5) Variable names, field names, and file names should avoid the same name as command verbs, keywords or function names to avoid confusion during runtime.

    5, what is constant? What is a variable? And briefly describe its basic type?
    : The constant refers to the amount that the value of the program does not change during the running of the program. Variables refer to the amount where the value of the program is changed.
    The basic types of the constant mainly include: numerical type, character type, logic, date type, date time type, currency type;
    basic types of variables mainly include: field variables and memory variables.

    6. How is the priority of the operation determined in an expression containing various operators?
    : The operating symbols commonly used in the expression include arithmetic operator, relationship operator, and logical operator. The priority of the operation is an arithmetic operator-> Relationship operator-> logical operator.
    Tlabing operator: ()->^->*or/-> or-
    Relationship operator:>> =, u003C, u003C=, =, u003C> according to the order of writing Priority
    Logical operators: Not-> AND-> OR

    7, what are the basic processes of analyzing the design database?
    : The basic process of designing the database is:
    (1) Analyze data requirements;
    (2) determine the required data table;
    (3) determine the required field;
    (4) Determine the inter -table connection;
    (5) perfect design

    8, comparative analysis logic deletion and physical deletion? And what is the relationship between them?
    : Logic deletion: refers to the deletion mark "*" to the data table, which is effective when set deleted on; physical deletion: the recorded in the data table is truly removed.
    The relationship between logic deletion and physical deletion is: when you need to delete the records in the data table, first delete the mark "*" to achieve logic deletion. At this time The "*" record is really removed by the delete mark, and the recovery of the recalted instruction cannot be recovered.

    9. What principles should be followed by trying to determine that the field in the data table should follow?
    Answer: What principles should be followed to determine what fields should be followed include:
    (1) field uniqueness;
    (2) field irrelevant;
    (3) use the main keywords of the main keywords ;
    (4) External keywords;
    (5) All information required for receivables;
    (6) Storage information with the smallest logical unit.

    10, what is index? What are the indexes in the database? What are the characteristics of each?
    : The index is a set of pointers to sort logically according to the value of the keyword. It provides a fast access to data, and can enforce the uniqueness of each line of the table.
    The indexes and main features in the database are:
    (1) Main index: It can ensure the uniqueness of the input value in the field and determine the order of processing records. Generally, the main key field is used to create a main index for each table. Do not build indexes for free tables.
    (2) Candidate index: It can also determine the uniqueness of the field value. Candidate indexes can be established in multi -free tables and database tables, and the main index in one table is unique, but the candidate index is not unique. The field outside the field is a candidate index.
    (3) Unique index: As far as the system only saves the first index value in the index file, that is, only the value of the same key value when the first key value appears.
    (4) Ordinary index: The values ​​and expressions in the allowable field can be repeated and can be used for sorting or search.
    This questions (chapters 4-6) Answer questions
    1. What is a view? Which method can VFP use to create views? Essence
    This: Views can be regarded as a virtual table from one or more basic tables or exported from other views. VFP can create views through various ways such as view wizard, view designer, and SQL command.
    2. What is a query? Which method can VFP use to create query?
    This: The main point: The query is to extract the records of the condition from one or more associated tables or views in the specified table or view, and then follow the direction of the direction of the direction of the direction of the output type. VFP can create views by querying wizards, query designers, and SQL commands.
    3. What are the foundations of query and view? What is the difference between query and view?
    This: Views and queries are an important means for the relationship database to provide user operating tables. They are based on the SQL Select statement and are a very useful tool. The main difference between viewing and query is: (1) The view generates a definition, which can be preserved in the database, and you can use the view like an operating table. In the presence, you can run the query file. (2) The view can be updated, and the update result can be sent back to the source table; the query cannot be updated. (3) The query results may set multiple directions as needed; and views cannot be.
    4. What is SQL language? What are the advantages of SQL language?
    This: SQL (Query Language structured query language) is a very common functional database standard language. The functions include query, definition, operation, and control. The main advantages of SQL language are: (1) non -processing language; (2) unified language; (3) simple language, easy to learn and easy to use; (4) the same language, two ways of use.
    5. What is Select-SQL query? How to use Select-SQL in VFP?
    This: SELECT-SQL query is a sentence query provided by the SQL language. It has powerful single-table and multi-table query functions. In VFP, you can customize and execute the inquiries through auxiliary tools such as "Query Designer" or "View Designer", or you can directly use the Select-SQL statement for query.
    6. Briefly describe the three basic logical structures of structured programming.
    This: Sequential structure, branch structure and circulating structure. The order structure is executed in order in order in order of the writing of the command; the branch structure can be selected in two or more program paths according to the current values ​​of the specified conditions; the circulatory structure is controlled by the current value of the specified condition to control the sentence sequence of the cycle body. Whether to perform repeatedly.
    7. Which three input commands can be used in the VFP program, what are the similarities between them?
    This: Answer points: You can use three input commands in the VFP program. The similarities and similarities of their differences are: (1) Accept can only accept character data, no boundary fabrics are required. Finish. (2) The WAIT command can only accept a single character, no boundary symbols, and no need to press Enter key after entering. (3) The INPUT command can accept the numerical, character, logic, date, and date timing data. If it is a character -type data, you need to use the boundary symbol and enter the near -return car key to end.
    8. Try the similarities and differences between the subroutine, custom function and process.
    This: Sub -program, custom functions, and processes are a program segment that can be named. It is a module with a function -related and independent independent. The formats defined by the three are different. The subroutines and processes are called through the Do command, and the custom function is mainly called in the expression.
    9. What is the purpose of program debugging? What are the common errors in the program?
    This: The purpose of the program debugging is to check and correct the errors in the program to ensure the reliable operation of the program. Common errors in programs are: grammatical errors, errors and logical errors beyond the scope allowed by the system.
    10. What is the target program? Try to write the extension of several VFP target programs.
    This: Compile the VFP program to obtain the target program. The target program is a compact non -text file with fast running speed and can play a role in encrypted the source program. The expansion names: .fxp, .qpx, .mp, etc. were all target programs.

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