SQL query Statements

1.

SELECT * FROM table name

Select DISTINCT query list from table name//Redo Query

2. Conditional query

Select query list from table name where filter criteria;

SELECT * FROM Employees where salary>12000;

Select Last_Name, department_id from Emplyees where department_id!=90;

Select last_name,salary,commission_pct from Emplyees where salary>=10000 and salary<=20000;

SELECT * FROM employees where last_name like '%a% ';

SELECT * FROM employees where last_name like ' ___e_a% ';

SELECT * FROM employees where last_name like ' _\_% '; The 2nd character is _, which requires the function escape character \.

SELECT * FROM employees where last_name like ' _$_% ' escape ' $ ';

Filter by conditional expression:

Conditional operator:> < =! = <> >= <=

Filter by logical expression:

Function: Used to join conditional expressions

&& and: Two conditions are true, the result is true, and vice versa is False

|| And OR:

Logical operators: && | | 　　 ！ And Or not

Fuzzy query:

Like (with wildcard character with% 0 or any number of characters, _ any single character) between and in are NULL is NOT NULL

SQL query Statement