NEXJ
Tasks Done
Grace Links to read
About NexJ
Java
Tools
- Eclipse
- CodeBeamer Quick Tour[5]
- Installing process of CodeBeamer on Eclipse [6]
- Connect to the CodeBeamer Grace's account [7]
Mercurial
- Mercurial Version Control
- Installing in windows[8]
- Mozilla Mercurial [9]
- The Definitive Guide (book) [10]
- compare version controls [11]
- Understanding Mercurial [12]
- Tutorial-wiki [13]
- TortoiseHg Documentation[14]
- Eclipse-Mercurial [15]
- More about installation [16]
- Eclipse-Mercurial Video [17]-Demo
- Documentation for Eclipse-Mercurial [18]
Mercurial Documentation
- Some Basic Terms
- The .hg directory is the “real” repository, and all of the files and directories that coexist with it are said to live in the working directory. An easy way to remember the distinction is that the repository contains the history of your project, while the working directory contains a snapshot of your project at a particular point in history.
- The hg log command gives us a view of the history of changes in the repository. By default, this command prints a brief paragraph of output for each change to the project that was recorded. Each of these recorded events are called a changeset, because it can contain a record of changes to several files. Changeset is also referred to as change, cset, revision or rev.
- Changeset field has the format of a number, followed by a colon, followed by a hexadecimal (or hex) string. These are identifiers for the changeset. The hex string is a unique identifier: the same hex string will always refer to the same changeset in every copy of this repository. The number is shorter and easier to type than the hex string, but it isn't unique: the same number in two different clones of a repository may identify different changesets. changeset: 0:0a04b987be5a
- Some changesets, have a tag field. A tag is another way to identify a changeset, by giving it an easy-to-remember name. tag: tip
Database / Persistence
- JDBC [19]
- Relational database Management System[20]
- JDBC Driver [21]
- Drivers table[22]
- XML/Object Binding and Object Persistence = XStream + XBird
- Trigger
- A trigger is a specification that the database should automatically execute a particular function whenever a certain type of operation is performed. Triggers can be defined to execute either before or after any INSERT, UPDATE, orDELETE operation, either once per modified row, or once per SQL statement. If a trigger event occurs, the trigger's function is called at the appropriate time to handle the event.[23]
- Wiki
- Oracle Server Manual
- MySQL - Syntax [24]
- PostgreSQL- Syntax [25]
- Stored Procedures
- Transactions
Compare PostgreSQL and MySQL
- Postgre
- MySQL
- The current versions are MySQL 5.1 and PostgreSQL 8.4.
- PostgreSQL is a unified database server with a single storage engine. MySQL has two layers, an upper SQL layer and a set of storage engines. [26]
- MySQL began development with a focus on speed while PostgreSQL began development with a focus on features and standards. Thus, MySQL was often regarded as the faster of the two.
- Both PostgreSQL and MySQL support Not-Null, Unique, Primary Key and Foreign Key constraints. However MySQL silently ignores the CHECK constraint
- MySQL supports stored procedures, per se; PostgreSQL supports stored functions, which are in practice very similar.
- Trigger - Both PostgreSQL and MySQL support triggers. A PostgreSQL trigger can execute any user-defined function from any of its procedural languages, not just PL/pgsql.MySQL triggers are activated by SQL statements only. They are not activated by changes in tables made by APIs that do not transmit SQL statements to the MySQL Server; in particular, they are not activated by updates made using the NDB API. PostgreSQL has always been strict about making sure data is valid before allowing it into the database, and there is no way for a client to bypass those checks.
- DataTypes - PostgreSQL does not have an unsigned integer data type, but it has a much richer data type support in several aspects: standards compliance, the logically fundamental data type BOOLEAN, user-defined data types mechanism, built-in and contributed data types. PostgreSQL allows columns of a table to be defined as variable-length multidimensional arrays. Arrays of any built-in or user-defined base type, enum type, or composite type can be created. Arrays of domains are not yet supported. MySQL does not have network IP address data types that PostgreSQL has but does provide INET_ATON() and INET_NTOA() functions to convert IPv4 addresses to and from easily stored integers. Postgres does very good job supporting referential integrity, has transactions and rollbacks, foreign keys ON DELETE CASCADE and ON UPDATE CASCADE.
- Security - MySQL has exceptionally good fine-grained access control. You can GRANT and REVOKE whatever rights you want, based on user name, table name and client host name.
- Alter table - Postgres supports ALTER TABLE to some extent. You can ADD COLUMN, RENAME COLUMN and RENAME TABLE. MySQL has all options in ALTER TABLE - you can ADD column, DROP it, RENAME or CHANGE its type on the fly - very good feature for busy servers, when you don't want to lock the entire database to dump it, change definition and reload it back.
- Diagnostic Log - By default, PostgreSQL logs to stderr, meaning that it's highly installation specific where the dianostic information is put; on this author's system, the default ends up in /var/lib/pgsql/pgstartup.log. The default can be set to something more reasonable (such as syslog on unix, eventlog on Windows) by adjusting thelog_destination configuration parameter.
- Automatic key generation -
- PostgreSQL doesn't support the standard's IDENTITY attribute. PostgreSQL's best offering for a column with auto-generated values is to declare a column of 'type' SERIAL:
CREATE TABLE tablename (
tablename_id SERIAL,
...
)- MySQL doesn't support the standard's IDENTITY attribute. As an alternative, an integer column may be assigned the non-standard AUTO_INCREMENT attribute:
CREATE TABLE tablename (
tablename_id INTEGER AUTO_INCREMENT PRIMARY KEY,
...
)