MySQL Tutorials - Herong's Tutorial Examples - v4.46, by Herong Yang
Table Column Types for Approximate Numbers
Describes 3 types of table columns to store approximate numbers: FLOAT, REAL and DOUBLE PRECISION.
There are 3 types of table columns to store approximate numbers: FLOAT, REAL and DOUBLE PRECISION.
"FLOAT(precision)" - Approximate numeric value with specified precision or higher. No scale is specified for FLOAT.
"REAL" - Approximate numeric value with no scale. Precision is defined by the implementation.
"DOUBLE PRECISION" - Approximate numeric value with no scale. Precision is defined by the implementation and should be higher than REAL.
Examples of approximate number column types, ApproximateNumberColumns.sql:
-- ApproximateNumberColumns.sql -- Copyright (c) 1999 HerongYang.com. All Rights Reserved. -- CREATE TABLE ApproximateNumber ( Line VARCHAR(8), X FLOAT(8), -- (precision) Y REAL, Z DOUBLE PRECISION ); INSERT INTO ApproximateNumber VALUES ( '1', 1.11, 2.22, 3.33 ); INSERT INTO ApproximateNumber VALUES ( '2', 11.1111, 22.2222, 33.3333 ); INSERT INTO ApproximateNumber VALUES ( '3', 111.111111, 222.222222, 333.333333 ); INSERT INTO ApproximateNumber VALUES ( '4', 2/3, 2/3, 2/3 ); SELECT * FROM ApproximateNumber; DROP TABLE ApproximateNumber;
Output:
Line X Y Z 1 1.11 2.22 3.33 2 11.1111 22.2222 33.3333 3 111.111 222.222222 333.333333 4 0.666667 0.666666666666667 0.666666666666667
Note that:
Table of Contents
MySQL Introduction and Installation
Introduction of MySQL Programs
Perl Programs and MySQL Servers
Java Programs and MySQL Servers
Character Strings and Bit Strings
►Table Column Types for Different Types of Values
Table Column Types for Character Strings
Table Column Types for Byte Strings
Table Column Types for Bit Strings
Table Column Types for Exact Numbers
►Table Column Types for Approximate Numbers
Table Column Types for Date and Time Values
Table Column Types for LOB (Large OBject)
Table Column Types for Look Up Values
Table Column Types for JSON Documents
Table Column Types for Spatial Geometry Data
Using DDL to Create Tables and Indexes
Using DML to Insert, Update and Delete Records
Using SELECT to Query Database
Window Functions for Statistical Analysis
Use Index for Better Performance
Transaction Management and Isolation Levels
Defining and Calling Stored Procedures
Variables, Loops and Cursors Used in Stored Procedures
System, User-Defined and Stored Procedure Variables
Storage Engines in MySQL Server
InnoDB Storage Engine - Primary and Secondary Indexes
Performance Tuning and Optimization
Installing MySQL Server on Linux