Eliminate duplicate rows with DISTINCT operator

Very often we might retrieve duplicate values from our records. In order to "see" only distinct records we can use the DISTINCT operator. The basic syntax for DISTINCT op...

How to test range of specified data by using then BETWEEN operator?

The BETWEEN operator is used to specify a range of data you want to test your result set against. The BETWEEN operator is frequently used with the

Usage of LIKE operator for searching database and similar queries

How to search through database? A simple way of creating searching queries is by using the LIKE operators. In broader terminology, the LIKE operators are used to...

Filtering data with IN operators

The IN operator is used to determine if a specified value matches any values returned by the query. The IN operator may be used with all main statements such as

How to use ANY (SOME) and ALL operators to filter queries?

The ANY and ALL operators allow you to perform a comparison between a single column value and a range of other values. In particular, the ANY operator will return a result if the o...

Sub-queries written with EXISTS or NOT EXISTS operators

Data sub-queries using EXISTS or

Testing retrieved values with IS NULL and IS NOT NULL

The IS NULL and IS NOT NULL operators are very useful in verifying if the returned value is a NULL type, or a valid one. Sometimes these NULL values will result in errors if not filtered properly a...