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SQL Cookbook
You know the rudiments of the SQL query language, yet you
feel you aren't taking full advantage of SQL's expressive
power. You'd like to learn how to do more work with SQL
inside the database before pushing data across the network
to your applications. You'd like to take your SQL skills to
the next level.
Let's face
it, SQL is a deceptively simple language to
learn, and many database developers never go far beyond the
simple statement: SELECT <columns> FROM <table>
WHERE <conditions>. But there is so much more you can
do with the language. In the SQL Cookbook, experienced SQL
developer Anthony Molinaro shares his favorite SQL
techniques and features. You'll learn about:
Window functions, arguably the most significant enhancement
to SQL in the past decade. If you're not using these, you're
missing out
Powerful, database-specific features such as SQL Server's
PIVOT and UNPIVOT operators, Oracle's MODEL clause, and
PostgreSQL's very useful GENERATE_SERIES function
Pivoting rows into columns, reverse-pivoting columns into
rows, using pivoting to facilitate inter-row calculations,
and double-pivoting a result set
Bucketization, and why you should never use that term in
Brooklyn.
How to create histograms, summarize data into buckets,
perform aggregations over a moving range of values, generate
running-totals and subtotals, and other advanced, data
warehousing techniques
The technique of walking a string, which allows you to use
SQL to parse through the characters, words, or delimited
elements of a string
Written in O'Reilly's popular Problem/Solution/Discussion
style, the SQL Cookbook is sure to please. Anthony's credo
is: "When it comes down to it, we all go to work, we all
have bills to pay, and we all want to go home at a
reasonable time and enjoy what's still available of our
days." The SQL Cookbook moves quickly from problem to
solution, saving you time each step of the way.
CONTENTS:
Preface
1. Retrieving Records
Retrieving All Rows and Columns from a Table
Retrieving a Subset of Rows from a Table
Finding Rows That Satisfy Multiple Conditions
Retrieving a Subset of Columns from a Table
Providing Meaningful Names for Columns
Referencing an Aliased Column in the WHERE Clause
Concatenating Column Values
Using Conditional Logic in a SELECT Statement
Limiting the Number of Rows Returned
Returning n Random Records from a Table
Finding Null Values
Transforming Nulls into Real Values
Searching for Patterns
2. Sorting Query Results
Returning Query Results in a Specified Order
Sorting by Multiple Fields
Sorting by Substrings
Sorting Mixed Alphanumeric Data
Dealing with Nulls when Sorting
Sorting on a Data Dependent Key
3. Working with Multiple Tables
Stacking One Rowset atop Another
Combining Related Rows
Finding Rows in Common Between Two Tables
Retrieving Values from One Table That Do Not Exist in Another
Retrieving Rows from One Table That Do Not Correspondto Rows in Another
Adding Joins to a Query Without Interfering with Other Joins
Determining Whether Two Tables Have the Same Data
Identifying and Avoiding Cartesian Products
Performing Joins when Using Aggregates
Performing Outer Joins when Using Aggregates
Returning Missing Data from Multiple Tables
Using NULLs in Operations and Comparisons
4. Inserting, Updating, Deleting
Inserting a New Record
Inserting Default Values
Overriding a Default Value with NULL
Copying Rows from One Table into Another
Copying a Table Definition
Inserting into Multiple Tables at Once
Blocking Inserts to Certain Columns
Modifying Records in a Table
Updating when Corresponding Rows Exist
Updating with Values from Another Table
Merging Records
Deleting All Records from a Table
Deleting Specific Records
Deleting a Single Record
Deleting Referential Integrity Violations
Deleting Duplicate Records
Deleting Records Referenced from Another Table
5. Metadata Queries
Listing Tables in a Schema
Listing a Table's Columns
Listing Indexed Columns for a Table
Listing Constraints on a Table
Listing Foreign Keys Without Corresponding Indexes
Using SQL to Generate SQL
Describing the Data Dictionary Views in an Oracle Database
6. Working with Strings
Walking a String
Embedding Quotes Within String Literals
Counting the Occurrences of a Character in a String
Removing Unwanted Characters from a String
Separating Numeric and Character Data
Determining Whether a String Is Alphanumeric
Extracting Initials from a Name
Ordering by Parts of a String
Ordering by a Number in a String
Creating a Delimited List from Table Rows
Converting Delimited Data into a Multi-Valued IN-List
Alphabetizing a String
Identifying Strings That Can Be Treated as Numbers
Extracting the nth Delimited Substring
Parsing an IP Address
7. Working with Numbers
Computing an Average
Finding the Min/Max Value in a Column
Summing the Values in a Column
Counting Rows in a Table
Counting Values in a Column
Generating a Running Total
Generating a Running Product
Calculating a Running Difference
Calculating a Mode
Calculating a Median
Determining the Percentage of a Total
Aggregating Nullable Columns
Computing Averages Without High and Low Values
Converting Alphanumeric Strings into Numbers
Changing Values in a Running Total
8. Date Arithmetic
Adding and Subtracting Days, Months, and Years
Determining the Number of Days Between Two Dates
Determining the Number of Business Days Between Two Dates
Determining the Number of Months or Years Between Two Dates
Determining the Number of Seconds, Minutes, or HoursBetween Two Dates
Counting the Occurrences of Weekdays in a Year
Determining the Date Difference Between the Current Recordand the Next Record
9. Date Manipulation
Determining if a Year Is a Leap Year
Determining the Number of Days in a Year
Extracting Units of Time from a Date
Determining the First and Last Day of a Month
Determining All Dates for a Particular Weekday Throughout a Year
Determining the Date of the First and Last Occurrence ofa Specific Weekday in a Month
Creating a Calendar
Listing Quarter Start and End Dates for the Year
Determining Quarter Start and End Dates for a Given Quarter
Filling in Missing Dates
Searching on Specific Units of Time
Comparing Records Using Specific Parts of a Date
Identifying Overlapping Date Ranges
10. Working with Ranges
Locating a Range of Consecutive Values
Finding Differences Between Rows in the Same Group or Partition
Locating the Beginning and End of a Range of Consecutive Values
Filling in Missing Values in a Range of Values
Generating Consecutive Numeric Values
11. Advanced Searching
Paginating Through a Result Set
Skipping n Rows from a Table
Incorporating OR Logic when Using Outer Joins
Determining Which Rows Are Reciprocals
Selecting the Top n Records
Finding Records with the Highest and Lowest Values
Investigating Future Rows
Shifting Row Values
Ranking Results
Suppressing Duplicates
Finding Knight Values
Generating Simple Forecasts
12. Reporting and Warehousing
Pivoting a Result Set into One Row
Pivoting a Result Set into Multiple Rows
Reverse Pivoting a Result Set
Reverse Pivoting a Result Set into One Column
Suppressing Repeating Values from a Result Set
Pivoting a Result Set to Facilitate Inter-Row Calculations
Creating Buckets of Data, of a Fixed Size
Creating a Predefined Number of Buckets
Creating Horizontal Histograms
Creating Vertical Histograms
Returning Non-GROUP BY Columns
Calculating Simple Subtotals
Calculating Subtotals for All Possible Expression Combinations
Identifying Rows That Are Not Subtotals
Using Case Expressions to Flag Rows
Creating a Sparse Matrix
Grouping Rows by Units of Time
Performing Aggregations over Different Groups/Partitions Simultaneously
Performing Aggregations over a Moving Range of Values
Pivoting a Result Set with Subtotals
13. Hierarchical Queries
Expressing a Parent-Child Relationship
Expressing a Child-Parent-Grandparent Relationship
Creating a Hierarchical View of a Table
Finding All Child Rows for a Given Parent Row
Determining Which Rows Are Leaf, Branch, or Root Nodes
14. Odds `n' Ends
Creating Cross-Tab Reports Using SQL Server's PIVOT Operator
Unpivoting a Cross-Tab Report Using SQL Server's UNPIVOT Operator
Transposing a Result Set Using Oracle's MODEL Clause
Extracting Elements of a String from Unfixed Locations
Finding the Number of Days in a Year (an Alternate Solution for Oracle)
Searching for Mixed Alphanumeric Strings
Converting Whole Numbers to Binary Using Oracle
Pivoting a Ranked Result Set
Adding a Column Header into a Double Pivoted Result Set
Converting a Scalar Subquery to a Composite Subquery in Oracle
Parsing Serialized Data into Rows
Calculating Percent Relative to Total
Creating CSV Output from Oracle
Finding Text Not Matching a Pattern (Oracle)
Transforming Data with an Inline View
Testing for Existence of a Value Within a Group
A. Window Function Refresher
B. Rozenshtein Revisited
Index
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