SQL (Structured Query Language) – TRUNCATE TABLE Command
The SQL TRUNCATE TABLE command is used to delete complete data from an existing table. You can also use DROP TABLE command to delete complete table but …
SQL (Structured Query Language) – ALTER TABLE Command
The SQL ALTER TABLE command is used to add, delete or modify columns in an existing table. You should also use the ALTER TABLE command to …
SQL (Structured Query Language) – Indexes
Indexes are special lookup tables that the database search engine can use to speed up data retrieval. Simply put, an index is a pointer to data in …
SQL (Structured Query Language) – Alias Syntax
You can rename a table or a column temporarily by giving another name known as Alias. The use of table aliases is to rename a table …
SQL (Structured Query Language) – NULL Values
The SQL NULL is the term used to represent a missing value. A NULL value in a table is a value in a field that appears to …
SQL (Structured Query Language) – UNIONS CLAUSE
The SQL UNION clause/operator is used to combine the results of two or more SELECT statements without returning any duplicate rows. To use this UNION …
SQL (Structured Query Language) – Using Joins
The SQL Joins clause is used to combine records from two or more tables in a database. A JOIN is a means for combining fields from two …
