, which is associated with a specific storage format, constraints, and a valid range of values.
When you create a table, you must specify a datatype for each of its columns.
Client sessions can use client character sets that are different from the database character set.
Consider the size of characters when you specify the column length for character datatypes.
You must consider this issue when estimating space for tables with columns that contain character data.
The length semantics of character datatypes can be measured in bytes or characters.
For single byte character sets, columns defined in character semantics are basically the same as those defined in byte semantics.
Character semantics are useful for defining varying-width multibyte strings; it reduces the complexity when defining the actual length requirements for data storage.
For example, in a Unicode database ( column that can store up to five Chinese characters together with five English characters.
Examples of character sets are 7-bit ASCII (American Standard Code for Information Interchange), EBCDIC (Extended Binary Coded Decimal Interchange Code), Code Page 500, Japan Extended UNIX, and Unicode UTF-8.
Oracle supports both single-byte and multibyte encoding schemes. For each row, Oracle Database stores each value in the column as a variable-length field unless a value exceeds the column's maximum length, in which case Oracle Database returns an error.