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SQL for beginners. Introduction. SQL is a language to query data. In most cases it is used to retrieve data from databases. Because SQL is so convenient, it may be used to query data that lives outside of databases (for example, you can use it with plain files). In day-to-day work of Data Engineers it plays a very important role.
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 · 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 ...
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.
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; -- result: 42.
This book is divided into 15 chapters and 3 appendixes: Chapter 1, A Little Background, explores the history of computerized databases, including the rise of the relational model and the SQL language. Chapter 2, Creating and Populating a Database, demonstrates how to create a
Let's Get Started Week 1 introduces SQL from a historical and theoretical perspective. The first statement you learn about is the SELECT statement, which enables you to retrieve data from the database based on various user-specified options. Also during Week 1 you study SQL functions, query joins, and SQL subqueries (a query within a query).
