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The PRIMARY KEY constraint uniquely identifies each record in a table. Primary keys must contain UNIQUE values, and cannot contain NULL values. A table can have only ONE primary key; and in the table, this primary key can consist of single or multiple columns (fields).
SQL (Structured Query Language) is a standard database programming language used for accessing and manipulating data in a database. This SQL tutorial series will help you learn SQL from the basics.
The SQL cheat sheet provides you with the most commonly used SQL statements for your reference. You can download the SQL cheat sheet as follows: Download 3-page SQL cheat sheet in PDF format. Querying data from a table. Query data in columns c1, c2 from a table. SELECT c1, c2 FROM t; Code language:SQL (Structured Query Language)(sql)
17 Φεβ 2021 · What can you do with SQL? Here's a reference guide to the most commonly-used SQL commands, with code examples you can copy-paste.
25 Σεπ 2020 · Aggregate functions. Example queries. Subqueries. Single value. Multiple values. Correlated. Set operations. UNION. INTERSECT. EXCEPT. Download this 2-page SQL Basics Cheat Sheet in PDF or PNG format, print it out, and stick to your desk.
Using the SQL CREATE TABLE statement, learn how to create a new table in a Relational Database Management System (RDBMS). Discover the basic syntax and options for creating tables, such as defining columns and their data types.
29 Αυγ 2024 · Unlock the power of SQL commands: DDL, DML, DCL, TCL, DQL with syntax. Explore this comprehensive guide to become proficient in SQL commands.
