Database Management - Lecture 2 - SQL select, insert, update and delete

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PRESENTATORS
MD. AL-MAMUN SARKAR

Why SQL
Execute queries against a database
Retrieve data from a database
Insert records in a database
Update records in a database
Delete records from a database
Create new databases
Create new tables in a database
Create views in a database

Important SQL Commands
 SELECT - extracts data from a database
 UPDATE - updates data in a database
 DELETE - deletes data from a database
 INSERT INTO - inserts new data into a database
 CREATE DATABASE - creates a new database
 ALTER DATABASE - modifies a database
 CREATE TABLE - creates a new table
 ALTER TABLE - modifies a table
 DROP TABLE - deletes a table
 CREATE INDEX - creates an index (search key)
 DROP INDEX - deletes an index

Select
SELECT * FROM table_name;
SELECT column1, column2, ...
FROM table_name;

SELECT DISTINCT
SELECT DISTINCT column_name FROM
table_name;

WHERE Clause
FROM table_name
WHERE condition;
Example:
SELECT * FROM students
WHERE age='15';

Operators
 = Equal
 <> Not equal. Note: ( != )
 > Greater than
 < Less than
 >= Greater than or equal
 <= Less than or equal
 BETWEEN Between an inclusive range
 LIKE Search for a pattern
 IN To specify multiple possible values for a column

AND, OR and NOT
AND
SELECT * FROM table_name
WHERE condition1 AND condition2 AND condition3;
OR
WHERE condition1 OR condition2 OR condition3 ;
NOT
WHERE NOT condition;

ORDER BY
FROM table_name
ORDER BY column ASC/DESC;
Example:
SELECT * FROM students ORDER BY id;
SELECT * FROM students ORDER BY id ASC;
SELECT * FROM students ORDER BY id DESC;

NULL
SELECT column_names
FROM table_name
WHERE column_name IS NULL;
SELECT column_names
FROM table_name
WHERE column_name IS NOT NULL;

INSERT
INSERT INTO table_name (column1, column2,
column3, ...)
VALUES (value1, value2, value3, ...);
INSERT INTO table_name
VALUES (value1, value2, value3, ...);

UPDATE
UPDATE table_name
SET column1 = value1, column2 = value2, ...
WHERE condition;

DELETE
DELETE FROM table_name
WHERE condition;
DELETE FROM table_name;
DELETE * FROM table_name;

Database Management - Lecture 2 - SQL select, insert, update and delete

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