Non-integer Numbers

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Synopsis

Floating-point and fixed-point numbers are used to specify non-integer numbers. Different floating point datatypes represent different precisions numbers.

Syntax

type_specification ::= { FLOAT | DOUBLE | DOUBLE PRECISION | DECIMAL }
non_integer_floating_point_literal ::= non_integer_fixed_point_literal | "NaN" | "Infinity" | "-Infinity"
non_integer_fixed_point_literal ::= [ + | - ] { digit [ digit ...] '.' [ digit ...] | '.' digit [ digit ...] }

Where

• Columns of type FLOAT, DOUBLE, DOUBLE PRECISION, or DECIMAL can be part of the PRIMARY KEY.
• DOUBLE and DOUBLE PRECISION are aliases.
• non_integer_floating_point_literal is used for values of FLOAT, DOUBLE and DOUBLE PRECISION types.
• non_integer_fixed_point_literal is used for values of DECIMAL type.

Semantics

• Values of different floating-point and fixed-point datatypes are comparable and convertible to one another.
  • Conversion from floating-point types into DECIMAL will raise an error for the special values NaN, Infinity, and -Infinity.
• Values of non-integer numeric datatypes are neither comparable nor convertible to integer although integers are convertible to them.
• The ordering for special floating-point values is defined as (in ascending order): -Infinity, all negative values in order, all positive values in order, Infinity, and NaN.

Examples

You can do this as shown below.

cqlsh:example> CREATE TABLE sensor_data (sensor_id INT PRIMARY KEY, float_val FLOAT, dbl_val DOUBLE, dec_val DECIMAL);

cqlsh:example> INSERT INTO sensor_data(sensor_id, float_val, dbl_val, dec_val) 
                  VALUES (1, 321.0456789, 321.0456789, 321.0456789);

Integers literals can also be used (Using upsert semantics to update a non-existent row).

cqlsh:example> UPDATE sensor_data SET float_val = 1, dbl_val = 1, dec_val = 1 WHERE sensor_id = 2;

cqlsh:example> SELECT * FROM sensor_data;

 sensor_id | float_val | dbl_val   | dec_val
-----------+-----------+-----------+-------------
         2 |         1 |         1 |           1
         1 | 321.04568 | 321.04568 | 321.0456789

See Also

Data Types