SQL and Oracle and Mysql Data Types

Structured Query Language (Structured Query Language), also known as structured query language, is a standard language for defining and querying and manipulating data in relational databases. It is an interface for communication between users and databases, almost all databases such as Oracle, MySQL, and SQL server support SQL queries. The SQL language has a simple structure, powerful functions, and is easy to learn. Therefore, since its launch, the SQL language has been widely used.

The SQL language consists of the following five sub-languages:

DDL-Data Definition Language );

Data Query Language (selete-query statements );

DML-datat manipulation language );

Transaction Control Language (TC-transaction control statements );

Data Control Language (DCL-datat control language );

Data Type

Oracle and MySQL are two important types of data. The following describes their basic data types.

Data Type	Data Type	Description
		Oracle	MySQL
Value Type	Number (P, S)	Stores numeric data types, such as floating point, integer, score, and dual-precision. Where p is the precision, indicating the total number of digits (1 <= P <= 38); s is the range, indicating the number of digits on the right of the decimal point, which is between-84 and 127. The default value is 38 characters.
	Tinyint		Tiny integer, 1 byte
	Smallint		Small integer, 2 bytes
	Mediumint		Medium integer, 3 bytes
	Int or integer	Integer Data Type	Integer, 4 bytes
	Bigint		Big integer, 8 bytes
	Float	Floating Point Data Type	Single-precision floating point value, 4 bytes
	Double		Double-precision floating point value, 8 bytes
	Decimal		For decimal (M, d), if M> D is m + 2, otherwise d + 2
String type	Char (N)	N = 1to2000 bytes, fixed length string, n Bytes long. If no length is specified, the default value is 1 byte long (one Chinese character is 2 bytes)	Fixed-length string, 0-bytes
	Nchar (N)	NLS (National Language Support, international language support) data types can only store UNICODE character sets defined by the database NLS character set. Oracle can store up to 2000 bytes
	Varchar (N)	A maximum of B can be stored in a variable length. Therefore, no space is required to fill in.	Variable-length string, 0-255 bytes
	Nvarchar (N)	N = 1to4000 bytes. A maximum of B bytes can be stored in a variable length. Therefore, no space is required for Supplement.	NLS (National Language Support, international language support) data types can only store UNICODE character sets defined by the database NLS character set.
	Varchar2 (N)	Varchar2 is more suitable for use than varchar. Due to compatibility, varchar remains in the Oracle database.
	Nvarchar2	The data type of NLS is equivalent to that of varchar2. This data type can be stored at most B.
	Clob	Stores a large amount of single-byte character data and multi-byte character data. The maximum storage capacity is 4 GB.
	Nclob	It stores variable-length Unicode Character Set character data with a maximum storage capacity of 4 GB.
	Blob	Stores large binary objects. Example: graphics, video, audio, etc.
	Bfile	Bfile: Specifies the file locator. It points to a binary file located in the file system of the server (storing a file path)
	Long	Storage of variable-length character data, up to 2 GB.
	Raw	Stores byte-based data. A maximum of 2000 bytes can be stored. The size must be specified. Raw data can be indexed.
	Long raw	Stores binary data of variable length. The maximum storage capacity is 2 GB. Cannot be indexed.
	Tinyblob		A binary string of no more than 255 characters, ranging from 0 to bytes.
	Tinytext		Short text string, 0-255 bytes
	Blob		Long text data in binary format, 0-65 535 bytes
	Text		Long text data, 0-65 535 bytes
	Mediumblob		Moderate-length text data in binary format
	Mediumtext		Medium-length text data, 0-16 777 215 bytes
	Logngblob		Extremely large text data in binary format, 0-4 294 967 295 bytes
	Longtext		Large text data, 0-4 294 967 295 bytes
Date and Time	Date	The date and time data of the table are stored in seven bytes. Each byte is stored in Century, year, month, day, hour, minute, and second. The value ranges from January 1, 4712 BC to December 31, 9999 AD. The sysdate function in Oracle returns the current date and time.	Date, YYYY-MM-DD
	Timestamp	The hour, minute, and second values of the year, month, day, and time of the storage date. The second value is accurate to the last six digits of the decimal point and contains the time zone information. The imestamp function in Oracle returns the current date, time, and time zone.
	Time		Time Value or duration, HH: mm: SS
	Year		Year Value, yyyy
	Datetime		Mixed date and time, YYYY-MM-DD hh: mm: SS
	Timestamp		Mixed Date and Time Value, timestamp, yyyymmdd hhmmss
Composite Type	Enum		An Enum type can contain a maximum of 65536 elements, one of which is retained by MySQL and used to store error information. This error value is represented by index 0 or an empty string.
	Set		Container type. A set type can contain up to 64 elements and cannot contain two identical elements.