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Nashville Housing DataCleaning.sql
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Nashville Housing DataCleaning.sql
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/*
----------------------------------------------------------------------------------------------------------------------------------------------------------
-------------------------------------------------------Cleaning Data-------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------------------------------------------------------
*/
------------Standardize Date Format--------------------------
Select * from portfolioproject.dbo.NashvilleHousing
Select SaleDate, convert(date,saledate)
from portfolioproject.dbo.NashvilleHousing
Update NashvilleHousing
Set SaleDate = convert(date,saledate)
Alter Table NashvilleHousing
Add SaleDateConverted Date;
Update NashvilleHousing
Set SaleDateConverted = convert(date,saledate)
Select SaleDateConverted
from portfolioproject.dbo.NashvilleHousing
----------------------------------------------------------------------------------
-- -------------------Populate Property Address Data------------------------------
Select *
From portfolioproject.dbo.NashvilleHousing
Where PropertyAddress is null
order by ParceliD
Select a.ParcelID, a.PropertyAddress, b.PArcelID, b.PropertyAddress, ISNULL(a.propertyaddress,b.propertyAddress)
From portfolioproject.dbo.NashvilleHousing a
Join portfolioproject.dbo.NashvilleHousing b
on a.ParcelID = b.parcelID
and a.[UniqueID] <> b.[UniqueID]
Where a.PropertyAddress is null
Update a
SET propertyAddress = ISNULL(a.propertyaddress,b.propertyAddress)
From portfolioproject.dbo.NashvilleHousing a
Join portfolioproject.dbo.NashvilleHousing b
on a.ParcelID = b.parcelID
and a.[UniqueID] <> b.[UniqueID]
Where a.PropertyAddress is null
----------------------------------------------------------------------------------
-------- Breaking out Address into Individual Columns ( Address, City, State)
Select *
From portfolioproject.dbo.NashvilleHousing
--Where PropertyAddress is null
--order by ParceliD
Select
SUBSTRING(PropertyAddress, 1, CHARINDEX(',', PropertyAddress)-1) as Address,
SUBSTRING(PropertyAddress, CHARINDEX(',', PropertyAddress) +1, Len(PropertyAddress)) as Address
From portfolioproject.dbo.NashvilleHousing
Alter Table portfolioproject.dbo.NashvilleHousing
Add PropertySplitAddress Nvarchar(255);
Update portfolioproject.dbo.NashvilleHousing
Set PropertySplitAddress = SUBSTRING(PropertyAddress, 1, CHARINDEX(',', PropertyAddress)-1)
Alter Table portfolioproject.dbo.NashvilleHousing
Add PropertySplitCity Nvarchar(255);
Update portfolioproject.dbo.NashvilleHousing
Set PropertySplitCity = SUBSTRING(PropertyAddress, CHARINDEX(',', PropertyAddress) +1, Len(PropertyAddress))
Select *
From portfolioproject.dbo.NashvilleHousing
Select OwnerAddress
From portfolioproject.dbo.NashvilleHousing
Select
PARSENAME(Replace(OwnerAddress,',','.'), 3),
PARSENAME(Replace(OwnerAddress,',','.'), 2),
PARSENAME(Replace(OwnerAddress,',','.'), 1)
From portfolioproject.dbo.NashvilleHousing
----------------------------------------------------------------------
Alter Table portfolioproject.dbo.NashvilleHousing
Add OwnerSplitAddress Nvarchar(255);
Update portfolioproject.dbo.NashvilleHousing
Set OwnerSplitAddress = PARSENAME(Replace(OwnerAddress,',','.'), 3)
-------------------------------------------------------------------------------
Alter Table portfolioproject.dbo.NashvilleHousing
Add OwnerSplitCity Nvarchar(255);
Update portfolioproject.dbo.NashvilleHousing
Set OwnerSplitCity = PARSENAME(Replace(OwnerAddress,',','.'), 2)
-------------------------------------------------------------------------------------
Alter Table portfolioproject.dbo.NashvilleHousing
Add OwnerSplitState Nvarchar(255);
Update portfolioproject.dbo.NashvilleHousing
Set OwnerSplitState =PARSENAME(Replace(OwnerAddress,',','.'), 1)
------------------------------------------------------------------------------------
Select *
From portfolioproject.dbo.NashvilleHousing
--------------------------------------------------------------------------------------------------------------------------------------------------
--------------------------------------------------------------------------------------------------------------------------------------------------
---- Change Y and N to Yes and No in "Sold as Vacant" field
Select Distinct(SoldAsVacant), Count(SoldAsVacant)
From portfolioproject.dbo.NashvilleHousing
Group by SoldAsVacant
Order by 2
Select SoldAsVacant,
Case When SoldAsVacant = 'Y' Then 'Yes'
When SoldAsVacant = 'N' Then 'No'
ELSE SoldAsVacant
END
From portfolioproject.dbo.NashvilleHousing
Update portfolioproject.dbo.NashvilleHousing
Set SoldAsVacant = Case When SoldAsVacant = 'Y' Then 'Yes'
When SoldAsVacant = 'N' Then 'No'
ELSE SoldAsVacant
END
------------------------------------------------------------------------------------------------------------------------------------------------------
-------------------------------------------------Remove Duplicates-------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------------------------------------------------------------
With RowNumCTE As(
Select * ,
ROW_NUMBER() OVER (
PARTITION BY ParcelID,
PropertyAddress,
SalePrice,
SaleDate,
LegalReference
ORDER BY
UniqueID
) as row_num
From portfolioproject.dbo.NashvilleHousing
--Order By ParcelID
)
DELETE
From RowNumCTE
Where row_num >1
Order by PropertyAddress
------------------------------------------------------------------------------------------------------------------------------------------------------
-------------------------------------------------Delete Unused Columns-------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------------------------------------------------------------
Select *
From portfolioproject.dbo.NashvilleHousing
ALTER TABLE portfolioproject.dbo.NashvilleHousing
DROP COLUMN OwnerAddress, TaxDistrict, PropertyAddress, Sale_Date