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Aug 17, 2023 · It has 129 interactive exercises on querying one or more tables, aggregating and grouping data, JOINs, subqueries, and set operations. Even with the 20 upcoming examples, we won’t show all the details or even all the basic-level queries.
- Ranking Rows Based on a Specific Ordering Criteria. Sometimes we need to create a SQL query to show a ranking of rows based on a specific order criteria.
- List The First 5 Rows of a Result Set. The next SQL query creates a report with the employee data for the top 5 salaries in the company. This kind of report must be ordered based on a given criteria; in our example, the order criteria will again be salary DESC
- List the Last 5 Rows of a Result Set. This query is similar to the top 5 query, but we want the last 5 rows. We only need to introduce a change in the type of order, i.e.
- List The Second Highest Row of a Result Set. Let’s suppose we’d like to obtain the data of the employee with the second highest salary in the company.
- Table of Contents. Introduction to JOIN. INNER JOIN. Example #1: Showing books and their authors. Example #2: Showing books and their translators. LEFT JOIN. Example #3: Showing all books alongside their authors and translators, if they exist.
- Introduction to JOIN. With relational databases, the information you want is often stored in several tables. In such scenarios, you’ll need to join these tables.
- INNER JOIN. We’ll start with a basic INNER JOIN, or simply, JOIN. This join type is used when we want to display matching records from two tables. Example #1: Showing books and their authors.
- LEFT JOIN. We’ll start our overview of OUTER joins with the LEFT JOIN. You should apply this SQL JOIN type when you want to keep all records from the left table and only the matched records from the right table.
An SQL query is a statement built by putting together various SQL commands. These SQL commands together perform a specific task to access, manage, modify, update, control, and organize your data stored in a database and managed via a DBMS. Why use SQL?
Home Tutorials SQL. SQL Tutorial: How To Write Better Queries. Learn about anti-patterns, execution plans, time complexity, query tuning, and optimization in SQL. Updated Dec 2022 · 35 min read.
Jan 1, 2024 · SQL provides much in-build function to perform operation of table data, these functions can be with-in SQL statements or queries, and can also be used within the programming environment provided by the SQL Server (Transact-SQL) database, such as stored procedures, functions, triggers, etc.
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Nov 9, 2022 · Introduction. When working with relational databases and Structured Query Language (SQL), you can store, manage, and retrieve data from the relational database management system. SQL can retrieve data intact, as stored within the database. SQL can also perform calculations and manipulate data through the use of functions.
