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Data Cleaning Project Queries.sql
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Data Cleaning Project Queries.sql
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-- Cleaning Data in SQL Queries
Select *
From [SQL Project].dbo.NashvilleHousing
-- Standardize Date Format
Select SaleDateConverted,CONVERT(Date,SaleDate)
From [SQL Project].dbo.NashvilleHousing
Update NashvilleHousing
SET SaleDate = CONVERT(Date,SaleDate)
-- -- If it doesn't Update properly
ALTER TABLE NashvilleHousing
Add SaleDateConverted Date;
Update NashvilleHousing
SET SaleDateConverted = CONVERT(Date,SaleDate)
--- Populate Property Address data
Select *
From [SQL Project].dbo.Nashvillehousing
--where PropertyAddress is null
order by ParcelID
Select a.ParcelID,a.PropertyAddress, b.ParcelID,b.PropertyAddress, ISNULL(a.propertyaddress,b.PropertyAddress)
From [SQL Project].dbo.Nashvillehousing a
JOIN [SQL Project].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 [SQL Project].dbo.NashvilleHousing a
JOIN [SQL Project].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 PropertyAddress
From [SQL Project].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 [SQL Project].dbo.NashvilleHousing
ALTER TABLE NashvilleHousing
Add PropertySplitAddress Nvarchar(255);
Update NashvilleHousing
SET PropertySplitAddress = SUBSTRING(PropertyAddress, 1, CHARINDEX(',', PropertyAddress) -1 )
ALTER TABLE NashvilleHousing
Add PropertySplitCity Nvarchar(255);
Update NashvilleHousing
SET PropertySplitCity = SUBSTRING(PropertyAddress, CHARINDEX(',', PropertyAddress) + 1 , LEN(PropertyAddress))
Select *
From [SQL Project].dbo.NashvilleHousing
Select OwnerAddress
From [SQL Project].dbo.NashvilleHousing
Select
PARSENAME(REPLACE(OwnerAddress, ',', '.') , 3)
,PARSENAME(REPLACE(OwnerAddress, ',', '.') , 2)
,PARSENAME(REPLACE(OwnerAddress, ',', '.') , 1)
From [SQL Project].dbo.NashvilleHousing
ALTER TABLE NashvilleHousing
Add OwnerSplitAddress Nvarchar(255);
Update NashvilleHousing
SET OwnerSplitAddress = PARSENAME(REPLACE(OwnerAddress, ',', '.') , 3)
ALTER TABLE NashvilleHousing
Add OwnerSplitCity Nvarchar(255);
Update NashvilleHousing
SET OwnerSplitCity = PARSENAME(REPLACE(OwnerAddress, ',', '.') , 2)
ALTER TABLE NashvilleHousing
Add OwnerSplitState Nvarchar(255);
Update NashvilleHousing
SET OwnerSplitState = PARSENAME(REPLACE(OwnerAddress, ',', '.') , 1)
Select *
From [SQL Project].dbo.NashvilleHousing
------ -- Change Y and N to Yes and No in "Sold as Vacant" field
Select Distinct(SoldAsVacant), Count(SoldAsVacant)
From [SQL Project].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 [SQL Project].dbo.NashvilleHousing
Update 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
) row_num
From [SQL Project].dbo.NashvilleHousing
--order by ParcelID
)
Select *
From RowNumCTE
Where row_num > 1
Order by PropertyAddress
Select *
From [SQL Project].dbo.NashvilleHousing
-- Delete Unused Columns
Select *
From [SQL Project].dbo.NashvilleHousing
ALTER TABLE [SQL Project].dbo.NashvilleHousing
DROP COLUMN TaxDistrict, PropertyAddress
-----------------------------------------------------------------------------------------------
-----------------------------------------------------------------------------------------------
--- Importing Data using OPENROWSET and BULK INSERT
-- More advanced and looks cooler, but have to configure server appropriately to do correctly
-- Wanted to provide this in case you wanted to try it
--sp_configure 'show advanced options', 1;
--RECONFIGURE;
--GO
--sp_configure 'Ad Hoc Distributed Queries', 1;
--RECONFIGURE;
--GO