Mysql, Oracle, and Java Data types _mysql

Mysql, Oracle, and Java Data types

Mysql	Oracle	Java
BIGINT	NUMBER (19,0)	Java. lang. Long
BIT	RAW	Byte []
BLOB	BLOB RAW	Byte []
CHAR	CHAR	Java. lang. String
DATE	DATE	Java. SQL. Date
DATETIME	DATE	Java. SQL. Timestamp
DECIMAL	FLOAT (24)	Java. math. BigDecimal
DOUBLE	FLOAT (24)	Java. lang. Double
DOUBLE PRECISION	FLOAT (24)	Java. lang. Double
ENUM	VARCHAR2	Java. lang. String
FLOAT	FLOAT	Java. lang. Float
INT	NUMBER (10, 0)	Java. lang. Integer
INTEGER	NUMBER (10, 0)	Java. lang. Integer
LONGBLOB	BLOB RAW	Byte []
LONGTEXT	CLOB RAW	Java. lang. String
MEDIUMBLOB	BLOB RAW	Byte []
MEDIUMINT	NUMBER (7,0)	Java. lang. Integer
MEDIUMTEXT	CLOB RAW	Java. lang. String
NUMERIC	NUMBER
REAL	FLOAT (24)
SET	VARCHAR2	Java. lang. String
SMALLINT	NUMBER (5, 0)	Java. lang. Integer
TEXT	VARCHAR2 CLOB	Java. lang. String
TIME	DATE	Java. SQL. Time
TIMESTAMP	DATE	Java. SQL. Timestamp
TINYBLOB	RAW	Byte []
TINYINT	NUMBER (3, 0)	Java. lang. Boolean
TINYTEXT	VARCHAR2	Java. lang. String
VARCHAR	VARCHAR2 CLOB	Java. lang. String
YEAR	NUMBER	Java. SQL. Date (Date is set to, January 1, February 1)

// Relationship between the number of bytes

Java byte count

Data type size (binary digits) range default value byte (byte) 8-128-127 0 shot (short integer) 16-32768-32768 0int (integer) 32-2147483648-2147483648 0 long (long integer) 64-9233372036854477808-9233372036854477808 0 float (float type) 32-3.40292824e + 38-3.40292824e + 38 0.0 fdouble (double precision) 64-1.79769313486231570E + 308-1.79769313486231570E + 308 0.0 dchar (character type) 16'/u0000-u/ffff ''/u000000'

Boolean (boolean) 1 true/false

What are the basic JAVA data types in bytes? Byte1 byte short2 byte int4 byte long8 byte char2 byte (1 byte in C) can store a Chinese character float4 byte double8 byte booleanfalse/true (theoretically occupies 1 bit, 1/8 bytes, 1 byte for actual processing)

                                   
JAVA adopts Unicode encoding. Each byte occupies 8 bits. Your computer system should be a 32-bit system, so each int is 4 bytes
               

One byte consists of eight binary digits.

Java has a total of eight basic data types (original data types): type storage requirements range (inclusive) default packaging class integer int 4 bytes (32-bit)-231 ~ 231-1 0 Integer number short 2 bytes (16 bits)-215 ~ 215-1 0 Short class long 8 bytes (64-bit)-263 ~ 263-1 0 Long byte 1 byte (8 bits)-27 ~ 27-1 0 Byte floating point float 4 bytes (32 bits)-3.4e + 38 ~ 3.4e + 38 0.0f Float type double 8 bytes (64-bit)-1.7e + 308 ~ 1.7e + 308 0 Double character char 2 byte (16 bits) u0000 ~ UFFFF (''~ '? ') '0' Character (0 ~ 216-1 (65535) boolean Boolean 1/8 bytes (1 bit) true, false FALSE boolean

In mobile development, due to the limitations of the memory of mobile devices, you must consider the number of bytes occupied by the data type. The following describes several basic data types in Java to deepen the memory.
There are a total of eight basic data types in Java, including four integer types and two floating point types, one character type is used to represent the character units of Unicode encoding and one boolean type used to represent the true value. (One byte equals eight bits)

1. integer
Remarks on the value range of bits required for type storage
Int 4-byte 4*8
Short 2-byte 2*8-32768 ~ 32767
Long 8-byte 8*8
Byte 1 byte 1x8-128 ~ 127

2. Floating point type
Remarks on the value range of bits required for type storage
Float 4-byte 4*8 float type value has a suffix F (for example, 3.14F)
Double 8 byte 8*8 floating point value without suffix F (for example, 3.14) the default value is double type

3. char type
Remarks on the value range of bits required for type storage
Char 2 bytes 2*8

4. boolean type
Remarks on the value range of bits required for type storage
Boolean 1 byte 1*8 false, true

Supplement: Java has a computation bag that can represent any precision. it is usually called "big number ). Although it is called a big value, it is not a Java type, but a Java object.

If the precision of the basic integer and floating point cannot meet the requirements, you can use java. two useful classes in the math package: BigIntegerBigDecimal (the Android SDK also contains java. math package and these two classes) these two classes can process values that contain numbers of any length. The BigInteger class implements integer operations with any precision, while the BigDecimal class implements floating point operations with any precision. For specific usage, see Java API.