SQL Server | Have you ever gave length in the Float data type declaration? | SQL Interview Question

19 Thursday Jul 2018

Posted by Pawan Kumar Khowal in Download SQL Interview Q's, SQL Concepts, SQL Performance Tuning, SQL Puzzles, SQL SERVER, SQL Server Interview Questions

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SQL Server Question | Have you ever gave length in the Float data type declaration? | SQL Interview Question

Well yes we can provide the length while declaring a Float data type, al though it is not compulsory. If you do not specify the length then SQL Server by default take that as FLOAT(53).

Syntax

--

float [ (n) ]

--

n – Where n is the number of bits that are used to store the mantissa of the float number in scientific notation
and, therefore, dictates the precision and storage size. If n is specified, it must be a value between 1 and 53.

Notes –

1. If you specify any value between 1-24 than SQL Server treats n as 24.
2. If you specify any value between 25-53 than SQL Server treats n as 53.
3. If you don’t specify any value than SQL Server treats n as 53.
4. If you specify n then it must be a value between 1 and 53.

N & the Storage Bytes

n value	Precision	Storage size
1-24	7 digits	4 bytes
25-53	15 digits	8 bytes

Range

Data type	Range
float	– 1.79E+308 to -2.23E-308, 0 and 2.23E-308 to 1.79E+308

Note

Conversion of float values that use scientific notation to decimal or numeric is restricted to values of precision 17 digits only. Any value < 5E-18 rounds down to 0.

Sample Example – 1 | Float without N

--

CREATE TABLE TestFloat
(
	 Id INT
	,Vals FLOAT
)
GO

OUTPUT
--
Commands completed successfully.

--

Here we have not specified any value so Prec should be 53

Sample Example – 2 | Float with N between 1 – 24

--

CREATE TABLE TestFloat1
(
	 Id INT
	,Vals FLOAT(10)
)
GO


OUTPUT
--
Commands completed successfully.


--

Here we have specified n value between 1-24 so Prec will be 24.

Sample Example – 3 | Float with N between 25-53

--

CREATE TABLE TestFloat2
(
	 Id INT
	,Vals FLOAT(49)
)
GO

OUTPUT
--
Commands completed successfully.


--

Here we have specified n value between 25-53 so Prec will be 53.

Sample Example – 4 | Float with N > 53

--

CREATE TABLE TestFloat3
(
	 Id INT
	,Vals FLOAT(54)
)
GO

--

In this case we shall get the below Error Message.

Msg 2750, Level 16, State 1, Line 34 Column or parameter #2: Specified column precision 54 is greater than the maximum precision of 53.

Enjoy 🙂

Please add comment(s) if you have one or multiple solutions in mind. Thank You.

Pawan Khowal

Pawan is a SQL Server Developer. If you need any help in writing code/puzzle or training please email at – pawankkmr”AT”gmail.com. Meanwhile please go throgh the top pages from his blog.

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SQL Puzzle | Remove trailing zeros puzzle – The DOUBLE PRECISION/FLOAT(53) data type | Advanced SQL

19 Thursday Jul 2018

Posted by Pawan Kumar Khowal in Download SQL Interview Q's, SQL Concepts, SQL Puzzles, SQL SERVER, SQL Server Interview Questions, SQL SERVER Puzzles, T SQL Puzzles, Tricky SQL Queries

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SQL Puzzle | Remove trailing zeros puzzle – The DOUBLE PRECISION/FLOAT(53) data type | Advanced SQL

In this puzzle you have to create a new columns from the vals column. In that column you need to remove the training zeros. So if a value is 13.90 then it should be 13.9 in the final output. For more details please refer the sample input data and the expected output.

Have you ever heard of DOUBLE PRECISION data type?

Well It is a floating point data type. Basically double precision is equivalent to float(53). I shall write one more post on Float[{n}] to explain this in detail.

Sample Input

Id	Vals
1	10.000
1	10.000
1	10.300
1	10.900
1	10.897
1	10.017
1	0.000

Expected Output

Id	Vals	NewVals
1	10.000	10
1	10.000	10
1	10.300	10.3
1	10.900	10.9
1	10.897	10.897
1	10.017	10.017
1	0.000	0

Script – DDL and INSERT Sample Data

--

CREATE TABLE RemoveTrailingZeros
(
	 Id SmallINT
	,Vals DECIMAL(10,3)
)
GO

INSERT INTO RemoveTrailingZeros VALUES
(1,10),
(1,10.00),
(1,10.3),
(1,10.9000),
(1,10.897),
(1,10.01700),
(1,0.000)
GO

SELECT * FROM RemoveTrailingZeros
GO

--

SOLUTION 1

--

SELECT * , CAST(Vals AS FLOAT) NewVals
FROM RemoveTrailingZeros


--

OUTPUT – 1

--

Id     Vals                                    NewVals
------ --------------------------------------- ----------------------
1      10.000                                  10
1      10.000                                  10
1      10.300                                  10.3
1      10.900                                  10.9
1      10.897                                  10.897
1      10.017                                  10.017
1      0.000                                   0

(7 rows affected)


--

SOLUTION 2

--

SELECT * , CAST(Vals AS FLOAT(53)) NewVals
FROM RemoveTrailingZeros


--

OUTPUT – 2

--

Id     Vals                                    NewVals
------ --------------------------------------- ----------------------
1      10.000                                  10
1      10.000                                  10
1      10.300                                  10.3
1      10.900                                  10.9
1      10.897                                  10.897
1      10.017                                  10.017
1      0.000                                   0

(7 rows affected)


--

SOLUTION 3

--

SELECT * , CAST(Vals AS DOUBLE PRECISION) NewVals
FROM RemoveTrailingZeros


--

OUTPUT – 3

--

Id     Vals                                    NewVals
------ --------------------------------------- ----------------------
1      10.000                                  10
1      10.000                                  10
1      10.300                                  10.3
1      10.900                                  10.9
1      10.897                                  10.897
1      10.017                                  10.017
1      0.000                                   0

(7 rows affected)


--

SOLUTION 4

--

SELECT * , CONVERT(DOUBLE PRECISION, Vals) NewVals
FROM RemoveTrailingZeros

--

OUTPUT – 4

--

Id     Vals                                    NewVals
------ --------------------------------------- ----------------------
1      10.000                                  10
1      10.000                                  10
1      10.300                                  10.3
1      10.900                                  10.9
1      10.897                                  10.897
1      10.017                                  10.017
1      0.000                                   0

(7 rows affected)

--

You can also use REAL. REAL = FLOAT(24)
The ISO synonym for real is float(24).

SOLUTION 5

--

SELECT * , CONVERT(REAL, Vals) NewVals
FROM RemoveTrailingZeros

--

OUTPUT – 5

--

Id     Vals                                    NewVals
------ --------------------------------------- ----------------------
1      10.000                                  10
1      10.000                                  10
1      10.300                                  10.3
1      10.900                                  10.9
1      10.897                                  10.897
1      10.017                                  10.017
1      0.000                                   0

(7 rows affected)

--