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SQL Handwritten Notes Repository: A collection of PDF notes covering SQL concepts with concise definitions and examples. Explore fundamental commands, date/time functions, joins, and more. Contributions welcome!
SQL Notes: Basics. Our SQL Basics Resource offers a comprehensive overview of essential SQL concepts and commands—crucial for anyone looking to master database management and manipulation. Download our free SQL PDF and get started with SQL notes to help you understand the core of this essential query language.
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;
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.
Mobile-friendly 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; -- result: 42.
Formatting and manipulating the data SQL Script Notes SELECT UPPER(first_name) FROM table_name; Function to display all data in upper case SELECT LOWER(first_name) FROM table_name; Function to display all data in lower case
In SQL, NULL is the value of an empty entry. This is di erent from the empty string ‘’ and the integer 0, both of which are not considered NULL. To check if an entry is NULL, use IS and IS NOT instead of = and !=. What if we don’t know which columns are NULL-free? Worse still, what if none of the columns are NULL-free? The solution is ...
