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 Tutorials
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 …
SQL (Structured Query Language) – Constraints
Constraints are the rules enforced on the data columns of a table. These are used to limit the type of data that can go into …
SQL (Structured Query Language) – SORTING Results
The SQL ORDER BY clause is used to sort the data in ascending or descending order, based on one or more columns. Some databases sort the query …
