Converting MSSQL function to MySQL function - mysql

Question

I am trying to convert this user defined function (taken from a MSSQL) and tweak it so that I can run it MYSQL. I have made several attempts but all seem to error on the declare variable.
I am running the following version: 5.6.11-log - MySQL Community Server (GPL)
USE [DataGB]
GO
/****** Object: UserDefinedFunction [dbo].[FullPostCodeFix] Script Date: 11/20/2013 16:10:44 ******/
SET ANSI_NULLS OFF
GO
SET QUOTED_IDENTIFIER OFF
GO
CREATE FUNCTION [dbo].[FullPostCodeFix] (#Postcode VARCHAR(20))
RETURNS VARCHAR(20)
BEGIN
/*
Puts postcode into correct format if it is currently in any of the below formats
AB12AA
AB 12AA
AB1 2AA
AB 1 2AA
Returns #Postcode
*/
DECL ARE #District Varchar(50)
DECLARE #Remainder Varchar(50)
DECLARE #Sector Varchar(50)
SET #District= CASE
WHEN LEN(#Postcode) - CHARINDEX(' ', REVERSE(#Postcode)) = len(#Postcode) THEN SUBSTRING(#Postcode,1,(len(#Postcode) - 3))
WHEN LEN(#Postcode) - CHARINDEX(' ', REVERSE(#Postcode)) < 3 THEN SUBSTRING(#Postcode,1,(len(#Postcode) - 3))
ELSE SUBSTRING(#Postcode, 0, LEN(#Postcode) - CHARINDEX(' ', REVERSE(#Postcode)) + 1)
END
SET #District = dbo.PostcodeFix(#District)
SET #Remainder= RIGHT(#Postcode,3)
SET #Sector = #District + ' ' + LEFT(#Remainder,1)
SET #Postcode = #District + ' ' + #Remainder
RETURN #Postcode
END
My attempt at creating a MYSQL version is below:
CREATE FUNCTION FullPostCodeFix (Postcode VARCHAR(20))
RETURNS VARCHAR(20)
BEGIN
DECLARE District Varchar(50)
DECLARE Remainder Varchar(50)
DECLARE Sector Varchar(50)
SET District= CASE
WHEN LEN(Postcode) - CHARINDEX(' ', REVERSE(Postcode)) = len(Postcode) THEN SUBSTRING(Postcode,1,(len(Postcode) - 3))
WHEN LEN(Postcode) - CHARINDEX(' ', REVERSE(Postcode)) < 3 THEN SUBSTRING(Postcode,1,(len(Postcode) - 3))
ELSE SUBSTRING(Postcode, 0, LEN(Postcode) - CHARINDEX(' ', REVERSE(Postcode)) + 1)
END
SET District = dbo.PostcodeFix(District)
SET Remainder= RIGHT(Postcode,3)
SET Sector = District + ' ' + LEFT(Remainder,1)
SET Postcode = District + ' ' + Remainder
RETURN Postcode
END
The error that I get is as follows:
Error Code: 1064. You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'DECLARE Remainder Varchar(50) DECLARE Sector Varchar(50)
There is another function called from within the function "FullPostCodeFix". This is my attempt:
DELIMITER $$
CREATE FUNCTION PostCodeFix (strDistrict VARCHAR(20))
RETURNS VARCHAR(20)
DETERMINISTIC
BEGIN
DECLARE intASCII INTEGER;
SET strDistrict = LTRIM(strDistrict);
SET strDistrict = RTRIM(strDistrict);
IF LENGTH(strDistrict) > 4 OR LENGTH(strDistrict) = 0 THEN RETURN 'ERROR: ' + strDistrict;
ELSE
BEGIN
SET intASCII = ASCII(LEFT(strDistrict, 1));
IF ( intASCII > 47 AND intASCII < 58 ) THEN RETURN 'ERROR: ' + strDistrict;
ELSE
BEGIN
SET intASCII = ASCII(SUBSTRING(strDistrict, 2, 1));
IF ( intASCII > 47 AND intASCII < 58 ) THEN SET strDistrict = LEFT(strDistrict, 1) + ' ' + RIGHT(strDistrict, LENGTH(strDistrict)-1);
SET intASCII = ASCII(SUBSTRING(strDistrict, 3, 1));
IF ( intASCII < 48 OR intASCII > 57 ) AND (intASCII <> 32) THEN RETURN 'ERROR: ' + strDistrict;
ELSE IF LENGTH(strDistrict) < 4 THEN SET strDistrict = LEFT(strDistrict, 2) + ' ' + RIGHT(strDistrict, LENGTH(strDistrict)-2);
END IF;
END IF;
RETURN strDistrict;
END IF;

Answer 1

Ok lets start, replace MS-SQL functions with MySQL equivalent functions.
MSSQL MySQL
LEN() LENGTH()
SUBTRING() SUBSTR()
CHARINDEX() INSTR()
below is documentation and list of all MySQL String functions
http://dev.mysql.com/doc/refman/5.0/en/string-functions.html
Here is correct MySQL Syntax that I have verified.
CREATE FUNCTION FullPostCodeFix (Postcode VARCHAR(20)) RETURNS VARCHAR(20)
BEGIN
DECLARE district VARCHAR(50);
DECLARE remainder VARCHAR(50);
DECLARE sector VARCHAR(50);
IF LENGTH(Postcode) - INSTR(' ', REVERSE(Postcode)) = LENGTH(Postcode) THEN SET district = SUBSTR(Postcode,1,(LENGTH(Postcode) - 3));
ELSEIF LENGTH(Postcode) - INSTR(' ', REVERSE(Postcode)) < 3 THEN SET district = SUBSTR(Postcode,1,(LENGTH(Postcode) - 3));
ELSE SET district = SUBSTR(Postcode, 0, LENGTH(Postcode) - INSTR(' ', REVERSE(Postcode)) + 1);
END IF;
SET District = dbo.PostcodeFix(District);
SET Remainder= RIGHT(Postcode,3);
SET Sector = CONCAT(District,' ',LEFT(Remainder,1));
SET Postcode = CONCAT(District,' ',Remainder);
RETURN Postcode;
END
Here is your second function
CREATE FUNCTION PostCodeFix (strDistrict VARCHAR(20))
RETURNS VARCHAR(20)
DETERMINISTIC
BEGIN
DECLARE intASCII INTEGER;
SET strDistrict = LTRIM(strDistrict);
SET strDistrict = RTRIM(strDistrict);
IF LENGTH(strDistrict) > 4 OR LENGTH(strDistrict) = 0 THEN RETURN 'ERROR: ' + strDistrict;
ELSE
SET intASCII = ASCII(LEFT(strDistrict, 1));
IF ( intASCII > 47 AND intASCII < 58 ) THEN RETURN 'ERROR: ' + strDistrict;
ELSE
SET intASCII = ASCII(SUBSTRING(strDistrict, 2, 1));
IF ( intASCII > 47 AND intASCII < 58 ) THEN SET strDistrict = LEFT(strDistrict, 1) + ' ' + RIGHT(strDistrict, LENGTH(strDistrict)-1);
END IF;
SET intASCII = ASCII(SUBSTRING(strDistrict, 3, 1));
IF ( intASCII < 48 OR intASCII > 57 ) AND (intASCII <> 32) THEN RETURN 'ERROR: ' + strDistrict;
ELSEIF LENGTH(strDistrict) < 4 THEN SET strDistrict = LEFT(strDistrict, 2) + ' ' + RIGHT(strDistrict, LENGTH(strDistrict)-2);
END IF;
END IF;
RETURN strDistrict;
END IF;
END