我整理了一个简单的存储过程,其中传递了两个参数以使其更具动态性。我在“前两位数和记录计数”部分中使用了一个准备好的语句来完成此操作。
我不确定是否也可以SET vTotalFT
使用准备好的语句使该部分动态化。
目前我必须对表名和字段进行硬编码。我希望vTotalFT
根据准备好的动态 SQL 语句分配我的变量,但我不确定语法。这个想法是,当我调用我的过程时,我可以告诉它使用哪个表和哪个字段进行分析。
CREATE PROCEDURE `sp_benfords_ft_digits_analysis`(vTable varchar(255), vField varchar(255))
SQL SECURITY INVOKER
BEGIN
-- Variables
DECLARE vTotalFT int(11);
-- Removes existing table
DROP TABLE IF EXISTS analysis_benfords_ft_digits;
-- Builds base analysis table
CREATE TABLE analysis_benfords_ft_digits
(
ID int(11) NOT NULL AUTO_INCREMENT,
FT_Digits int(11),
Count_of_Records int(11),
Actual decimal(18,3),
Benfords decimal(18,3),
Difference Decimal(18,3),
AbsDiff decimal(18,3),
Zstat decimal(18,3),
PRIMARY KEY (ID),
KEY id_id (ID)
);
-- First Two Digits and Count of Records
SET @s = concat('INSERT INTO analysis_benfords_ft_digits
(FT_Digits,Count_of_Records)
select substring(cast(',vField,' as char(50)),1,2) as FT_Digits, count(*) as Count_of_Records
from ',vTable,'
where ',vField,' >= 10
group by 1');
prepare stmt from @s;
execute stmt;
deallocate prepare stmt;
SET vTotalFT = (select sum(Count_of_Records) from
(select substring(cast(Gross_Amount as char(50)),1,2) as FT_Digits, count(*) as Count_of_Records
from supplier_invoice_headers
where Gross_Amount >= 10
group by 1) a);
-- Actual
UPDATE analysis_benfords_ft_digits
SET Actual = Count_of_Records / vTotalFT;
-- Benfords
UPDATE analysis_benfords_ft_digits
SET Benfords = Log(1 + (1 / FT_Digits)) / Log(10);
-- Difference
UPDATE analysis_benfords_ft_digits
SET Difference = Actual - Benfords;
-- AbsDiff
UPDATE analysis_benfords_ft_digits
SET AbsDiff = abs(Difference);
-- ZStat
UPDATE analysis_benfords_ft_digits
SET ZStat = cast((ABS(Actual-Benfords)-IF((1/(2*vTotalFT))<ABS(Actual-Benfords),(1/(2*vTotalFT)),0))/(SQRT(Benfords*(1-Benfords)/vTotalFT)) as decimal(18,3));