Using the where clause in SQL

Returns only the values of rows that meet the conditions specified in the WHERE clause.

Example:

SELECT customer_name FROM table_customers WHERE gender = "M"

 

Operators

Description

Equal

Not Equal

Different

Greater

Less

No Minor

No greater

Greater Than or Equal

Less Than or Equal

Each of them can be used in search conditions to form the relational predicates.

BETWEEN - AND: Specifies data included in a certain range.

Can be used with numbers as with dates:

SELECT CustomerID, Name FROM Customer WHERE table_customers DateNasc BETWEEN "1997-01-01" AND "04/31/1997"

SELECT CustomerID, Name FROM Customer WHERE table_customers suppliersID BETWEEN 1 AND 9


IS NUL: Allows you to select rows where the contents of the field is null (BLANK).

SELECT CustomerID FROM WHERE table_Requests DateRequests IS NULL

LIKE: Allows you to use masking characters to compare data in a search condition on text values. We use two characters

 

Mask

Replace a single character:  _ or ;
Replace a sequence of characters: % or *.
SELECT FROM table_customers WHERE nameCustomers  LIKE "RIC%";
SELECT FROM table_customers WHERE nameCustomers  LIKE "J_A_";
 

IN: Allows you to select data that fit a set or more list of values


SELECT CustomerID, customer-name FROM table_nameCustomers WHERE CustomerID IN ("ABCDE", "ZXED", "WW3CD")