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This article mainly introduces which five types of MySQL data types, the article is very detailed, has a certain reference value, interested friends must read it!

1. The data type of MySQL

It mainly includes the following five categories:

Integer types: BIT, BOOL, TINY INT, SMALL INT, MEDIUM INT, INT, BIG INT

Floating point type: FLOAT, DOUBLE, DECIMAL

String types: CHAR, VARCHAR, TINY TEXT, TEXT, MEDIUM TEXT, LONGTEXT, TINY BLOB, BLOB, MEDIUM BLOB, LONG BLOB

Date type: Date, DateTime, TimeStamp, Time, Year

Other data types: BINARY, VARBINARY, ENUM, SET, Geometry, Point, MultiPoint, LineString, MultiLineString, Polygon, GeometryCollection, etc.

1. Integer

MySQL data type meaning (signed) tinyint (m) 1 byte range (- 128 '127) smallint (m) 2 byte range (- 32768' 32767) mediumint (m) 3 byte range (- 8388608 '8388607) int (m) 4 byte range (- 2147483648' 2147483647) bigint (m) 8 byte range (+-9.22'10 to the power of 18)

If the value range is added with unsigned, the maximum value is doubled, for example, the value range of tinyint unsigned is (0,256).

The m in int (m) represents the display width of the SELECT query result set, does not affect the actual range of values, does not affect the display width, I do not know what the use of this m.

2. Floating point type (float and double)

MySQL data type meaning float (m) single precision floating point precision (4 bytes) m total number, d decimal places double (m gravity d) double precision floating point precision (8 bytes) m total number, d decimal places

Let a field be defined as float (6p3). If you insert a number of 123.45678, what is actually stored in the database is 123.457, but the total number is still based on the actual number, that is, 6 digits. The maximum integer part is 3 digits, if the insertion number is 12.123456, the storage is 12.1234, and if the insertion is 12.12, the storage is 12.1200.

3. Fixed point number

Floating-point types store approximate values in the database, while fixed-point types store exact values in the database.

Decimal (m _ m _ d) parameter m

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