What is the length limit for Oracle table name, field name, constraint name, respectively?

Article Source: http://blog.csdn.net/haiross/article/details/38379615

1 Oracle: Table name, field name, constraint name are limited in length2 3 naming rules for Oracle:41, to start with a letter52, contains letters and numbers, and # $63, cannot exceed 30 characters7 8 This is the limitation of Oracle! 9 Ten database table name length limit problem One Modify the database table name today, feel the existing definition column names have no meaning ... After the change was told by colleagues, the column name is a bit long, afraid of some database does not support.  A  - The first time I heard about database table name and column name length limit, so search under.  -  the Table name names -  -MySQL 64 64 -  +Oracle 30 30 -  +DB2 128 128 A  atAccess 64 64 -  -MSSQL 128 128 -  - are online looking for, do not know, there is no time to find their documents to see. It seems that Oracle can modify the maximum limit ... I hope some crossing can treatise -  in What is the length limit for Oracle table name, field name, constraint name, respectively?  -Any object in Oracle that needs to be named must have no more than 30 characters in its identifier, because the data type of the data dictionary table that is related to the system table that records information about these database objects has already been defined such size. You can look up the data dictionary, which has a definition, followed by user_tables,user_tab_columns,user_constraints. For example, the data type defined for the table name in this system table view is VARCHAR2 (30), which means that the field can be up to 30 bytes in User_tables.

What is the length limit for Oracle table name, field name, constraint name, respectively?