CN105653277A - Method for querying appointed field data of data table under simplified JAVA program, multi-table conjunctive query method under simplified JAVA program and statistical query method under simplified JAVA program - Google Patents

Abstract

The invention discloses a method for querying the appointed field data of a data table under a simplified JAVA program. The method comprises the following steps: creating a data entity class corresponding to a table field one by one; describing a field name to be queried by a character string array; creating a corresponding sql (Structured Query Language) query statement, and initiating and obtaining a result; utilizing reflection to map the result data to each attribute of a corresponding data entity object; and during data operation, directly utilizing a "get" method in the object to read a certain value.

Description

A kind of simplify under JAVA program inquire about tables of data designated field data, multilist conjunctive query, statistical query method

Technical field

The invention belongs to computer programming field, particularly to a kind of method simplifying and inquiring about tables of data designated field data, multilist conjunctive query, statistical query under JAVA program.

Background technology

Under existing JAVA program, it will usually have following several " out-of-date methods " that a query portion field data can be accomplished, but be required for writing the code of extra bulk redundancy, wherein:

1. it is likely to write the building method of multiple correspondent entity class for various inquiry fields.

Example: if " name " field in inquiry UserInfo table

PublicUserInfo (Stringname) { this.name=name; }

Or inquire about " name " " age " " address " in table

Then when writing inquiry, the actual building method writing certain needs of use

Stringhql=" selectnewUserInfo (name) fromUserInfo ";

......

The shortcoming of this mode is first to create corresponding building method for different query demands, it is impossible to the pure exploitation being absorbed in service logic.

2. it is that the inquiry field that each is possible creates mapping entity class, during inquiry, calls correspondent entity class. Its essence is consistent with method 1, only replaces building method by a new class. To be created that the entity class of correspondence when shortcoming is still that exploitation for business demand, then have and process the logic development calling these classes, the logic that different types of result data is processed, it is impossible to be absorbed in real service logic exploitation.

3. inquire about by pure SQL statement. Can accomplish relatively to be absorbed in the exploitation in service logic, however it is necessary that developer understands SQL syntax, and correctly write. The code major part of exploitation is the SQL statement with character string forms, it may occur that cacography in character string, the composition error between character string and parameter; Mistake investigation, later stage revise difficult in maintenance; Code Core is not object-oriented, couples closely with actually used type of database

4. utilize the method that third party's framework provides, it is possible to accomplishing to be absorbed in service logic exploitation, need not write SQL statement, code complies fully with the thought of object-oriented. Shortcoming be it should be understood that framework mechanism it is known that and grasp use its offer method; Needing also exist for writing more, step is various and a certain amount of redundant code. To use " Hibernate ", simplest it is accomplished by

// 1. query object DetachedCriteria being created that the table entity class with inquiry

// 2. object set ProjectionList creating inquiry field definition

// 3. create each field object Projections to inquire about and it are put into one by one in ProjectionList

ProjectionList object value is given to DetachedCriteria query object by // 4.

The result data of return is put in certain data carrier type by // 5. definition

// 6. perform, with the DetachedCriteria querying method being parameter, to obtain result

Summary of the invention

It is an object of the invention to provide a kind of method inquiring about tables of data designated field data, multilist conjunctive query, statistical query under JAVA program, to simplify existing written in code.

The technical scheme is that, a kind of simplify under JAVA program inquire about tables of data designated field data method, including step:

Create and literary name section classes of data entities one to one;

The field name to inquire about is described with character string dimension;

It is created that the sql query statement of correspondence, initiates inquiry and obtain result;

Reflection is utilized to be mapped to by result data in each attribute of data entity object of correspondence;

Then directly some value is read by " get " method in object during operation data.

A kind of simplify the method for multilist conjunctive query under JAVA program, including step:

The method pole adopting above-mentioned inquiry tables of data designated field data joins the inquiry of multiple contingency tables;

By the form of " some attribute-name in type object name the type " of association in character string dimension during definition conjunctive query;

Adopt " innerjoin " mode to associate between acquiescence multilist, time specifically used, specify " right/leftjoin ".

A kind of simplify the method for statistical query under JAVA program, adopt the method for above-mentioned inquiry tables of data designated field data and the method for multilist conjunctive query, and take following steps:

Create the object of statistics that specifically to use, including statistics field name and the pattern (utilizing the several statistical model of enumeration type definition " max, min, sum, avg, count ") of statistics;

The field name of " groupby " is described with character string dimension.

The beneficial effect comprise that

SQL statement need not be write;

Multiple entity class need not be created in advance and define multiple building methods;

It is simple method by various and redundancy the code wrap of step that originally to write, substantially reduce the number size of code;

Amendment when inquiry is changed has only to the inquiry word name section character string dimension of amendment definition;

It is consistent that basic query writes mode with conjunctive query, it is not necessary to extra size of code, and can infinitely join pole;

Type and the method for those specific functions in framework need not be paid close attention to.

Accompanying drawing explanation

Fig. 1 is that in the present invention, class and Property Name thereof and tables of data and field thereof map.

Fig. 2 is user message table in the embodiment of the present invention.

Fig. 3 is inquiry user data procedure chart in the embodiment of the present invention.

Fig. 4 is blog table in the embodiment of the present invention.

Fig. 5 is the procedure chart inquiring about blog data in the embodiment of the present invention.

Fig. 6 is the procedure chart inquiring about many sections of blog data in the embodiment of the present invention.

Detailed description of the invention

The operating principle that the method for the present invention relates to includes:

A. class is created, defined attribute, writes the get/set method of attribute, and class and Property Name thereof and tables of data and field thereof is mapped, as it is shown in figure 1, be created that this object of query object can define all of settings that can inquire about such as the wheregroupby of inquiry based on this;

B. will inquire about some field corresponding generic attribute title mode putting character string dimension into represent;

C. circulate character string dimension, each Property Name is set in query object, the field that inquire about is set;

D. the data of the data acquisition system got are put in entity class by write method, and this entity class is generally the class mapped with table, it is also possible to being other classes other, such must provide for get/set method;

E. the inquiry of multilist conjunctive query, polymerization calculating can be expanded based on method described above.

Wherein, basic methods is:

1. create and literary name section classes of data entities one to one;

2. the field name to inquire about is described with character string dimension;

3. method can be created that the sql query statement of correspondence, initiate inquiry and obtain result;

4. utilize reflection to be mapped to by result data in each attribute of data entity object of correspondence;

5. then directly read some value by " get " method in object during operation data.

It is exemplified below:

1. assuming there is a user message table " UserInfo ", as in figure 2 it is shown, wherein, " address " and " remarks " field there may be bigger data volume to list structure, does not generally directly inquire about acquisition

2. perform the process of inquiry user data, as it is shown on figure 3, wherein,

Actual queries " id, name, age, gender " field of table

Finally directly obtain the data set of " List<UserInfo>" type to operate data

Multilist conjunctive query method is:

1. infinitely can open the inquiry of contingency table by connection n in pole on basic methods principle;

2. Method And Principle is consistent with basic methods with step;

3. character string dimension is used during definition conjunctive query the form of " some attribute-name in type object name the type " of association;

4. adopt " innerjoin " mode to associate between acquiescence multilist, time specifically used, may specify " right/leftjoin ". It is exemplified below:

1. assuming there is a blog table " Blog ", associate with " UserInfo ", list structure is as shown in Figure 4. Article content is big text data type, and userId associates " id " of user's table " UserInfo ".

2. the title inquiring about blog inquires owning user name simultaneously, performs process as shown in Figure 5. " id, time, the timeFlag " field of actual queries " Blog " table and " name " field of " UserInfo " table; Finally directly obtain the data set of " List<Blog>" type to operate data.

Statistical query method is:

1. create the object of statistics specifically used, including

1) add up field name;

2) pattern (utilizing the several statistical model of enumeration type definition " max, min, sum, avg, count ") added up;

2. the field name of " groupby " is described with character string dimension;

3. other to realize principle consistent with multilist conjunctive query with basic methods principle.

It is exemplified below:

Inquire about each user and have several sections of blogs, perform process as shown in Figure 6. Wherein, owing to the result of statistical query return is generally inconsistent with the classes of data entities form being queried statistics, it is necessary to defining an object " BlogCount " for carrying result data, this object does not map with any tables of data.

Claims (3)

1. one kind simplifies the method inquiring about tables of data designated field data under JAVA program, it is characterised in that include step:

Create and literary name section classes of data entities one to one;

The field name to inquire about is described with character string dimension;

It is created that the sql query statement of correspondence, initiates inquiry and obtain result;

Reflection is utilized to be mapped to by result data in each attribute of data entity object of correspondence;

Then directly some value is read by " get " method in object during operation data.

2. one kind simplifies the method for multilist conjunctive query under JAVA program, it is characterised in that include step:

The method of claim 1 pole is adopted to join the inquiry of multiple contingency tables;

By the form of " some attribute-name in type object name the type " of association in character string dimension during definition conjunctive query;

Adopt " innerjoin " mode to associate between acquiescence multilist, time specifically used, specify " right/leftjoin ".

3. one kind simplifies the method for statistical query under JAVA program, it is characterised in that adopts the method as described in claim 1 and claim 2, and takes following steps:

Create the object of statistics that specifically to use, including statistics field name and the pattern (utilizing the several statistical model of enumeration type definition " max, min, sum, avg, count ") of statistics;

The field name of " groupby " is described with character string dimension.