Practical sql: a beginner’s Guide to Storytelling with Data pdfdrive com
EXTRACTING INFORMATION BY GROUPING AND
tải về 5.77 Mb. Chế độ xem pdf
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EXTRACTING INFORMATION BY GROUPING AND SUMMARIZING Creating the Library Survey Tables Creating the 2014 Library Data Table Creating the 2009 Library Data Table Exploring the Library Data Using Aggregate Functions Counting Rows and Values Using count() Finding Maximum and Minimum Values Using max() and min() Aggregating Data Using GROUP BY Wrapping Up Try It Yourself 9 INSPECTING AND MODIFYING DATA Importing Data on Meat, Poultry, and Egg Producers Interviewing the Data Set Checking for Missing Values Checking for Inconsistent Data Values Checking for Malformed Values Using length() Modifying Tables, Columns, and Data Modifying Tables with ALTER TABLE Modifying Values with UPDATE Creating Backup Tables Restoring Missing Column Values Updating Values for Consistency Repairing ZIP Codes Using Concatenation Updating Values Across Tables Deleting Unnecessary Data Deleting Rows from a Table Deleting a Column from a Table Deleting a Table from a Database Using Transaction Blocks to Save or Revert Changes Improving Performance When Updating Large Tables Wrapping Up Try It Yourself 10 STATISTICAL FUNCTIONS IN SQL Creating a Census Stats Table Measuring Correlation with corr(Y, X) Checking Additional Correlations Predicting Values with Regression Analysis Finding the Effect of an Independent Variable with r-squared Creating Rankings with SQL Ranking with rank() and dense_rank() Ranking Within Subgroups with PARTITION BY Calculating Rates for Meaningful Comparisons Wrapping Up Try It Yourself 11 WORKING WITH DATES AND TIMES Data Types and Functions for Dates and Times Manipulating Dates and Times Extracting the Components of a timestamp Value Creating Datetime Values from timestamp Components Retrieving the Current Date and Time Working with Time Zones Finding Your Time Zone Setting Setting the Time Zone Calculations with Dates and Times Finding Patterns in New York City Taxi Data Finding Patterns in Amtrak Data Wrapping Up Try It Yourself tải về 5.77 Mb. Chia sẻ với bạn bè của bạn:
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