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Function coalesce(column_1, column_2, ...) takes two or more arguments (columns or other values like strings, numbers) and return first non-NULL argument. Principle of work: check if first argument is NULL. if yes, go to the next step, otherwise return the argument
* 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
1 maj 2023 · That’s all in this list of Free SQL books for beginners and experienced developers. You can download these books as free PDF or read them online as well.
Learning SQL eBook (PDF) Download this eBook for free. Chapters. Chapter 1: Getting started with SQL. Chapter 2: ALTER TABLE. Chapter 3: AND & OR Operators. Chapter 4: Cascading Delete. Chapter 5: CASE. Chapter 6: Clean Code in SQL.
1 cze 2021 · Standard SQL Functions Cheat Sheet. TEXT FUNCTIONS. CONCATENATION. Use the || operator to concatenate two strings: SELECT 'Hi ' || 'there!'; -- result: Hi there! Remember that you can concatenate only character strings using. ||. Use this trick for numbers: SELECT '' || 4 || 2;
Fetch all names that start with any letter followed by 'atherine': SELECT name FROM names WHERE name LIKE '_atherine'; Fetch all names that end with 'a': SELECT name FROM names WHERE name LIKE '%a'; USEFUL FUNCTIONS. Get the count of characters in a string: SELECT LENGTH('LearnSQL.com');-- result: 12 Convert all letters to lowercase: SELECT ...
this book demonstrates many of the SQL schema statements, the main focus of this book is on programming features. With only a handful of commands, the SQL data statements look deceptively simple.
