SQL Cheatsheet - SELECT FROM WHERE clauses with examples

SQL Cheat sheet for beginners, SELECT clause, FROM clause, WHERE clause explained with examples.

 

 SELECT ... FROM ... WHERE clauses in SQL - Cheat sheet

Querying data using SELECT…FROM...WHERE clauses in SQL
Commands/Clauses	Examples
SELECT 👈 To view required data from one or more tables.   Syntax: SELECT parameters FROM tablename;   Parameters for SELECT: *, list of attributes, functions, arithmetic operations are the parameters for the command (clause) SELECT.	Parameters examples for SELECT clause Simple: SELECT * FROM student; Result: Displays all columns of all records of student table. List of attributes: SELECT name, phone FROM student; Result: Displays only name and phone of all students; Function: SELECT MAX(salary) FROM employee; Result: Displays the maximum of all salary values stored in employee table. Operations: SELECT Basic + HRA FROM employee; Result: Displays the sum of the values stored in Basic and HRA columns (attributes) of all employee records.
FROM 👈 To specify the name of the table/view from which we want to view the data.   Syntax: SELECT parameters FROM tablename; Parameters for FROM: Table name or table names separated with comma.	Parameters examples for FROM clause Single table: SELECT * FROM employee; Result: Displays all records from employee table. Multiple tables: SELECT * FROM employee, dept; Result: It is a special case. It performs join. Displays columns of tables, employee and dept with every record of table employee combined with every record of dept.
WHERE 👈 To specify one or more conditions to filter the data to view/get required data only.   Syntax: SELECT parameters FROM tablename WHERE condition;   Parameters for WHERE: WHERE clause accepts the conditions (predicates) of the following format; Attribute_name OP value; Attribute_name OP attribute_name; Here, OP refers to OPERATOR that can be one of =, <>, >, <, >=, and <=   More conditions can be mentioned in WHERE clause. In that case, the conditions should be connected using logical connectives AND, OR, NOT.	Parameter examples for WHERE clause attribute_name OP value: SELECT * FROM employee WHERE gender = ‘male’; Result: Displays all records of employee who are MALE.   SELECT * FROM employee WHERE salary > 10000; Result: Displays all records of employees who earn more than 10000.   SELECT name, age FROM employee WHERE salary = 25000; Result: Displays only name and ages of all employees who earn 25000. attribute_name OP attribute_name: SELECT * FROM employee, dept WHERE emp_dno = dept_dno;

 

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