कोर्स परिचय

SQL Server में फंक्शंस और स्टोरड प्रोसीजर्स लिखना

Meghan Kwartler

IT Consultant

कोर्स उद्देश्यों

SQL date functions से temporal exploratory data analysis (EDA) करें
User-Defined Functions बनाएँ, अपडेट करें, चलाएँ
Stored Procedures बनाएँ, अपडेट करें, चलाएँ
पूर्व-आवश्यकताएँ
- Introduction to SQL Server
- Joining Data in SQL
- Intermediate SQL Server

Temporal EDA

Transactional datasets
- CapitalBikeShare
- YellowTripTaxi
Exploratory Data Analysis (EDA) प्रक्रिया
- Iterative
- EDA प्रश्नों की कोई तय चेकलिस्ट नहीं
- जिज्ञासु बनिए!
- दोबारा काम कम होता है

EDA विज़ुअल

EDA के लिए SQL functions

-- CONVERT Syntax:  
CONVERT ( data_type [ ( length ) ] , expression [ , style ] )  
-- Returns expression based on data_type

-- DATEPART Syntax
DATEPART ( datepart , date ) 
-- Returns int

-- DATENAME Syntax
DATENAME ( datepart , date ) 
-- Returns nvarchar

-- DATEDIFF Syntax
DATEDIFF ( datepart , startdate , enddate ) 
-- Returns int; can't use datepart weekday value

-- datepart values = year, quarter, month, dayofyear, day, week, weekday, hour, 
-- minute, second, microsecond, nanosecond

-- CONVERT
SELECT 
  TOP 1 PickupDate, 
  CONVERT (DATE, PickupDate) AS DateOnly 
FROM YellowTripData

+-----------------------------+------------+
| PickupDate                  | DateOnly   |
|-----------------------------+------------|
| 2017-01-09 11:52:13.0000000 | 2017-01-09 |
+-----------------------------+------------+

-- DATEPART
SELECT 
  TOP 3 COUNT(ID) AS NumberofRides, 
  DATEPART(HOUR, PickupDate) AS Hour 
FROM YellowTripData 
GROUP BY DATEPART(HOUR, PickupDate) 
ORDER BY COUNT(ID) DESC

+----------------------+
| NumberOfRides | Hour |
|----------------------+
| 616281        | 18   |
| 616281        | 19   |
| 540629        | 17   |
+---------------+------+

--DATENAME
SELECT 
  TOP 3 ROUND(
    SUM(FareAmount), 
    0
  ) as TotalFareAmt, 
  DATENAME(WEEKDAY, PickupDate) AS DayofWeek 
FROM YellowTripData 
GROUP BY DATENAME (WEEKDAY, PickupDate) 
ORDER BY SUM(FareAmount) DESC;

+--------------------------+
| TotalFareAmt | DayofWeek |
|--------------------------+
| 19026645     | Sunday    |
| 18749482     | Tuesday   |
| 17213351     | Thursday  |
+--------------+-----------+

--DATEDIFF
SELECT 
  AVG(
    DATEDIFF(SECOND, PickupDate, DropOffDate)/ 60
  ) AS AvgRideLengthInMin 
FROM YellowTripData 
WHERE DATENAME(WEEKDAY, PickupDate) = 'Sunday';

+--------------------+
| AvgRideLengthInMin |
|--------------------+
| 13                 |
+--------------------+

अभ्यास करते हैं!

SQL Server में फंक्शंस और स्टोरड प्रोसीजर्स लिखना