Introduces a C ++ ORM tool ODB

Source: http://blog.csdn.net/CAICHAO1234/article/details/8997051

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I learned about ORM (Object link ing) some time ago, and then I found the C ++ ORM framework. I found that there are very few such frameworks:

Name	Open Source	License	Requires support from specific frameworks	Supports QT	Boost supported	Support for MySQL	Support for PostgreSQL	SQLite supported	Supports XML	Support for Oracle	Support for MSSQL Server	Supports ODBC	Support for IBM DB2
Litesql	Yes	BSD	No	Yes		Yes	Yes	Yes
ODB	Yes	GPL/Other	No	Yes	Yes	Yes	Yes	Yes		Yes
Qxorm	Yes	Lgpl	Yes, QT	Yes	Yes	Yes	Yes	Yes		Yes	Yes	Yes	Yes
Wt: DBO	Yes	GPL/commercial	Yes, WT	No	Yes	Yes	Yes	Yes	No	No	No	No	No

Litesql uses XML to define the form, and it seems that it writes the support of all databases to a dynamic link library, so it is relatively large, qxqrm, wt :: DBO depends on a specific framework. Therefore, we feel that ODB is the most suitable for development. Official website portal

ODB support features

• Automatically generate code supported by the database (cross-database)
• Ability to process any standard C ++ code (no development platform restrictions)
• Compile and generate database forms based on class definitions (you can configure compilation commands in Visual Studio)
• A form exists in the form of an independent SQL file or an SQL code embedded in C ++.
• Supports object-oriented persistence models and database APIs (provides easy-to-use database operation methods)
• Supports expressions or Type-safe object query languages
• ODB uses Version Control
• Supports local SQL Execution
• Supports SQL tracking (the output window can output the currently executed SQL statements in real time)
• Cross-platform connection pool to ensure thread security

About ing

• By default, all basic C ++ types and STD: string are mapped.
• Automatically maps the C ++ enumerated object to the enum type or Integer type of the database.
• Supports blob ing blob to STD: vector <char>
• Supports merging value types (automatically parsed into multiple fields)
• Supports null semantic ing to smart pointers, such as ODB: nullable or boost: Optional.
• Allows you to allocate table names to persistent classes.
• Field names can be allocated to data members.
• Supports ing c ++ type to Database Type
• ID of an object that supports automatic assignment
• Supports persistence classes without IDs
• Support read-only/constant data members
• Allows you to use custom smart pointers as pointers to objects, views, and values.
• Support for Cache Technology (using session)

For more information, see the ODB manual.

I wrote a small example to fully understand the ODB (version 1.7.0 ). In general, it is good, but the problem is still relatively large when applied to actual projects.

First, the Union primary key is not supported, and there are no check and unique constraints. This is officially recognized.

Although lazyload is provided to improve efficiency, it is not convenient to use it.

The query is not flexible. You can only set the query conditions in the part after the WHERE clause. For example, you must define a view for the existence of a query (select exists) and the number of queries (select count). This is really troublesome.

Batch deletion is slow and inflexible. At the advanced level, only deletion based on query conditions is provided, but this is far from enough. Although the SQL Execution interface is opened, the original design of the ORM tool is damaged, it also brings trouble for future maintenance.

Has the function (software implementation) corresponding to the trigger, provides callback, supports common events of the trigger, before and after deletion, and new before and after addition. However, I tried to add a deletion to trigger another table's data deletion and compilation failed. Why?

No software implementation for stored procedures and cursors

 

The following is the running result of the source code of the Attachment:

Attachment download:

Http://dl.dbank.com/c07l5w5k7x

(You need to download the ODB compilation on the official website and add it to the VC directory. We recommend that you use the IDE of vs2008sp1 or later or the boost library because smart pointers are required)