The difference between varchar2 and char in oracle

Key differences between VARCHAR2 and CHAR data types in Oracle: VARCHAR2: variable length, stores the actual string length; CHAR: fixed length, padded with spaces. VARCHAR2: high storage and retrieval efficiency; CHAR: fast retrieval, low storage and update efficiency. VARCHAR2: comparison is based on actual content; CHAR: comparison is based on padding length. VARCHAR2: stores variable-length strings; CHAR: stores fixed-length strings.

The difference between VARCHAR2 and CHAR in Oracle

In Oracle database, VARCHAR2 and CHAR are both used to store There are two data types of string data, and there are some key differences between them:

1. Storage length

• VARCHAR2: Variable length data type , the length of the stored string can be changed as needed. Maximum length is 4000 bytes.
• CHAR: Fixed-length data type, the length of the stored string is fixed. Maximum length is 2000 bytes.

2. Storage method

• VARCHAR2: Only the actual length of the string and the string itself are stored.
• CHAR: Always store the string as a fixed length, and fill the missing part with spaces.

3. Performance

• VARCHAR2: Due to its variable length, it is generally more efficient than CHAR when storing and retrieving data, because it Only store the space actually needed.
• CHAR: Because of its fixed length, retrieving data is faster, but may be less efficient when storing and updating data.

4. Comparison

• VARCHAR2: String comparisons are based on their actual contents.
• CHAR: String comparisons are based on their padding length, which means that even if the contents of the strings are the same, different lengths will result in different comparison results.

5. Usage scenarios

• VARCHAR2: Usually used to store variable length and long strings, such as comments, descriptions or text field.
• CHAR: Typically used to store strings of fixed length that must remain consistent, such as usernames, passwords, or codes.

Summary:

In short, VARCHAR2 is a variable-length data type suitable for storing variable-length strings, while CHAR is Fixed-length data type, suitable for storing fixed-length and consistent strings.

The above is the detailed content of The difference between varchar2 and char in oracle. For more information, please follow other related articles on the PHP Chinese website!