delphi对数据库的支持是非常强大的.一般我们对数据库的访问可以通过BDE,ADO或是其它的一些引擎,像现在比较高效的dbExpress就也是非常不错的.不过,一般对于桌面或是个人开发,我们还是用BDE,但是BDE实在是做的太差了,存在许多的问题,如客户端的配置就是很麻烦的一件事情.这里介绍的absolute database实在是再好不过的数据库了.不像其它数据库,absolute不但是个数据库,也是一款数据库引擎.安装完后,可以在BCB或delphi环境下生成控件,像BDE一样直接调用就可以了.但是更棒的一点是,在客户端中我们不需要太多的配置.甚至直接可以把数据库打包到可执行文件,真是太棒了.
absolute database有许多版本,对于简单开发,个人版就够了.其它的版本都是要付费的.在单用户模式(也就是一个数据库)下运行时数据库没有任何限制,不过在DELPHI环境启动时,也会出现他的启动屏幕,另外,在多用户模式下,也就是指在文件服务器模式下,运行状态,他的启动屏幕也会闪现的.所以,在使用的时候要注意这个问题.
下面是他的一些英文说明,不翻译了,大家自己看吧.
要了解详细情况,可以在 看到.
Absolute Database is a BDE alternative database system.With Absolute Database you will not need special installation and configuration, it compiles right into your application.
Some of Absolute DB key features are listed below:
Ease of Deployment
?No BDE, no DLLs, No OCXs
?No special installation or configuration required
?Database engine compiles right into EXE
?Single-file database format
?Database file could be merged with the application EXE file
High Speed
?Advanced cache management and buffering architecture
?Sophisticated SQL query and filter optimizer
?Special optimized database engine for temporary results of SQL queries
?Fast B*-Tree indexes with high-speed on thousands and on millions of records
?Buffered transactions for batch inserts, updates and deletes
?In-memory tables for fast operations with data loaded into memory
?Optimization for read-only databases, such as databases on CD
?High-concurrency design for multi-threaded applications
Multi-User
?Zero-admin file-server
?Automatic record and table locking
?Automatic detection of changes made by other users
?Configurable limit of concurrent connections
?Easy switching between single-user and multi-user mode
?Full transactions support with ReadCommited isolation level
SQL Support
?SELECT with DISTINCT, INNER LEFT, RIGHT, FULL and OUTER JOIN, GROUP BY and ORDER BY clauses
?CREATE TABLE, DROP TABLE, ALTER TABLE statements
?CREATE INDEX, DROP INDEX statements
?INSERT, UPDATE, DELETE statements
?BETWEEN, IN, LIKE, IS NULL, EXISTS operators
?Aggregate functions COUNT,SUM,MIN,MAX,AVG
?Most of all SQL'92 arithmetic, logical, date-time and string functions and operators
?Data types conversion by function CAST
?SQL scripts (multiple statements separated by ';')
?Parameters in queries
?SELECT from several databases in one query
?Correlated and non-correlated subqueries
Compactness
?Small size of code added into the application by the database engine units
?Small database file size achieved by customizable page size, compression of table metadata and other special means
?Automatic free space recycling for data records, index pages, and BLOB blocks
?Fast BLOB data compression
?Short indexes for string fields
?Low memory consumption
Compatibility
?Support of most of TTable field data types, including BLOB fields
?Full compatibility with standard DB-aware visual controls such as QuickReport, DBGrid, DBNavigator, DBImage, DBMemo, DBRichEdit and others
?Calculated and lookup fields
?Most of TTable functions including Key and Range methods
?Support for the IProvider interface (TClientDataSet)
Functionality
?Unicode support in String and Memo fields
?Multiple-fields indexes with descending, ascending, case-sensitive and insensitive options
?Shareable tables
?Default values support
?Min, max and not null constraints on field values
?Export to SQL script (reverse engineering)
Security
?Strong encryption of database file
?Variety of supported encryption algorithms: Rijndael, the Advanced Encryption Standard (AES) winner 128 bit key, Rijndael 256 bit key, Blowfish 448 bit key, Twofish 128 bit key, Twofish 256 bit key, Square, Single DES and Triple DES
Reliability
?Repair database in case of hardware failure or operating system error caused by another application
?Auto-detect of database corruption and automatic repair of database file
Convenience
?Table restructuring being performed in the easiest way keeping all the existing data
?Data importing from and exporting to any dataset
?Internationalization / localization support by use of current system locale
?Displaying progress during potentially slow operations with the tables and databases
Utilities
?DBImportExport utility to transfer your existing tables from database systems with BDE driver, such as Paradox, Interbase, Access, Oracle, SQL Server to Absolute Database format and vice versa.
?Absolute Database Manager to manage a database easily and to perform all supported operations with tables and database file
?With Absolute Database Manager you could also easily execute SQL queries
?All utilities come with the full source code and can be used as an advanced examples
Ease of Development
?Full compatibility with TTable, TQuery, TSession and TDatabase components
?Extensive Developer's Manual covering every development issue.
?Large number of demos illustrating wide range of use cases
?Prompt and responsive technical support
Cost-Effectiveness
?100% royalty-free, i.e. there is no additional licensing fees no matter how many times you deploy the application
?Flexible licensing: source code and no source code versions, multi-developers licenses
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