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XLeratorDB/math Documentation

SQL Server ROW function


Updated: 31 January 2012

Use the scalar function MROW to return a row from the string representation of a matrix.
MROW expects a string representation of the matrix, with columns separated by commas and rows separated by semi-colons.
SELECT [wctMath].[wct].[MROW](
  <@Matrix, nvarchar(max),>
 ,<@m, int,>)
a string representation of a matrix.
The row number. Row number is a 1-based index.
Return Types
·         The string representations of @Matrix must only contain numbers, commas (to separate the columns), and semi-colons to separate the rows.
·         Consecutive commas will generate an error.
·         Consecutive semi-colons will generate an error.
·         Non-numeric data between commas will generate an error
·         Non-number data between semi-colons will generate an error
·         To convert non-normalized data to a string format, use the Matrix2String or the Matrix2String_q function.
·         To convert normalized data to a string format, use the NMatrix2String or the NMatrix2String_q function.
·         @m must be greater than or equal to 1.
·         If @m is greater than the number of rows an error message will be generated.
·         To determine the number of columns in the matrix, use the MROWS function.
Let’s assume that we had the following matrix, A, and we want to return the fifth row.
A = [-79,-45,9,9,-91,-5;68,46,9,81,-61,35;83,-25,80,-67,-22,-38;77,40,-24,69,73,-20;-17,-72,-9,-72,-6,-34;64,-47,48,-54,18,11;-4,-36,7,-56,-34,-3;-41,90,78,-43,38,64;-60,-85,-31,-83,-96,-36;-40,31,-93,-62,64,10]
We could enter the following SQL to perform the calculation.
DECLARE @A as varchar(max)
SET @A = '-79,-45,9,9,-91,-5;68,46,9,81,-61,35;83,-25,80,-67,-22,-38;77,40,-24,69,73,-20;-17,-72,-9,-72,-6,-34;64,-47,48,-54,18,11;-4,-36,7,-56,-34,-3;-41,90,78,-43,38,64;-60,-85,-31,-83,-96,-36;-40,31,-93,-62,64,10'
SELECT wct.MROW(@A, 5) as [Row]
This produces the following result.
The matrix does not have to be assigned to a variable before passed into the MROW function; the string can be passed in directly.
SELECT wct.MROW('-79,-45,9,9,-91,-5;68,46,9,81,-61,35;83,-25,80,-67,-22,-38;77,40,-24,69,73,-20;-17,-72,-9,-72,-6,-34;64,-47,48,-54,18,11;-4,-36,7,-56,-34,-3;-41,90,78,-43,38,64;-60,-85,-31,-83,-96,-36;-40,31,-93,-62,64,10', 5) as [Row]
This produces the following result.

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