MySQL Most Common Commands!
MySQL Database Conrtrol Commands
I was using the database command of MySQL, I thought I should share these to help the world with a collection of the most common command of MySQL. Let’s get started. If you would like my collection let me know in the comment box so I can work more to impove my blog to help you guys.
01 Create and Delete Database!
Creating Database:
Syntax:
CREATE SCHEMA DatabaseName;
create database DatabaseName;
Example:
CREATE SCHEMA School;
create database school;
DROP DATABASE
This command is used to delete a database along with the whole data present in the database that you have added.
Syntax:
DROP SCHEMA DataBaseName; –OR DROP DATABASE DatabaseName;
Example:
DROP SCHEMA School; -Or DROP DATABASE School;
How to select database as default?
If there is one database or many, then you will have make one as default to start work. So you will have to use command “USE”. Its syntax is USE DataBaseName;
For Example database name is College, then you will have to write this command. “USE”
USE College;
How to make comment in SQL?
If you have used a SQL command then you do not want to use that command, make it into comment.
Use this command. “–“
–use college;
02 Commands Related Table of Database
1. SELECT is used to extract data from a database
SELECT column_name
FROM table_name;
SELECT statements fetch data from a table of a database. It is very common command to check the data of table from a database.
There is one common patron to select all columns records. “*” star mean select all columns.
select * from school;
select all columns from table school
2. CREATE TABLE — creates a new table
CREATE TABLE table_name (
column_1 datatype,
column_2 datatype,
column_3 datatype
);
CREATE TABLE statements create a new table in the database of MySQl or SQL.
3. ALTER TABLE — modifies a table
ALTER TABLE table_name
ADD column_name datatype;
ALTER TABLE statements add, delete, or modify columns in an existing table of MySQL.
4. DROP TABLE — deletes a table
DROP TABLE table_name;
DROP TABLE statements drop an existing table in a database of MySQL.
5. UPDATE — updates data in a database
UPDATE table_name
SET some_column = some_value
WHERE some_column = some_value
UPDATE statements allow us to edit rows in a table of database. If “where” condition is not used then whole data will be updated. So be careful.
6. INSERT INTO — inserts new data into a database
INSERT INTO table_name (column_1, column_2, column_3)
VALUES (value_1, ‘value_2’, value_3);
INSERT statements add a new row or multiple rows to a table of database.
7. DELETE — deletes data from a database
DELETE FROM table_name
WHERE some_column = some_value;
DELETE statements remove rows from a table of database. If it “where” condition is not used then whole data will be deleted.
8. CREATE INDEX — creates an index
CREATE INDEX index_name
ON table_name (column_name1, column_name2…);
Index statements create on existing tables to retrieve the rows quickly and easily.
9. DROP INDEX — deletes an index
ALTER TABLE table_name
DROP INDEX index_name;
DROP INDEX statements delete an index in a table. very helpful
