sql command

FROM BOOK

SQL important commands

1) .

1)	database command
s.no.	want to use	command syntax	command means type these in sql	output
i)	CREATE DATABASE	create database [databasename] ex ;	CREATE DATABASE EMP1;	Query OK, 1 rows affected (0.05 sec)
ii)	SHOW DATABASE	SHOW [database name];	SHOW DATABASES;	+--------------------+ | Database | +--------------------+ | information_schema | | emp | | emp1 | | emp3 | | estdatabase | | junkdb | | mysql | | performance_schema | | raj | | students | | test | | testdatabase | | testdb | +--------------------+ 13 rows in set (0.84 sec)
iii)	USE OR SELECT or Switch to a database	use [db name];	USE EMP1;	mysql> USE EMP1; Database changed
iv)	To delete database	drop database [database name];	drop database emp1;	Query OK, 2 rows affected (0.23 sec)
v)	Add a new column to database
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2)	table command
s.no.	want to use	command syntax	command means type these in sql	output
(i)	Create Table or make table in database	CREATE TABLE [table name] (firstname VARCHAR(20));	CREATE TABLE employee (fname VARCHAR(20),lname VARCHAR(35));	Query OK, 0 rows affected (0.78 sec)
ii)	see all the tables in the db database		show tables;	+----------------+ | Tables_in_emp1 | +----------------+ | employee | | employee1 | +----------------+ 2 rows in set (0.02 sec)
(iii)	Manipulating Tables	totaly remove table from database	DROP TABLE EMPLOYEE;	Query OK, 0 rows affected (0.06 sec)
iv)	To remove a column from a table		ALTER TABLE EMPLOYEE DROP fname;	Query OK, 0 rows affected (0.33 sec) Records: 0 Duplicates: 0 Warnings: 0
11)	To see tables field formats	describe [table name];	describe EMPLOYEE;	+-------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------+-------------+------+-----+---------+-------+ | lname | varchar(35) | YES | | NULL | | +-------+-------------+------+-----+---------+-------+ 1 row in set (0.03 sec)
6)	To delete a table’s contents without removing the table completely		DELETE FROM EMPLOYEE;
7)	one statement to delete the same row from more than one table:		DELETE FROM EMPLOYEE, CONFIDENTIAL WHERE empno='00201';
8)	To retrieve a complete table		SELECT * FROM EMPLOYEE;
9)	all command insert one time store in a file		source books.sql
10)	To login (from unix shell) use -h only if needed.		# [mysql dir]/bin/mysql -h hostname -u root -p
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				h	Query OK, 0 rows affected (0.05 sec)

CREATE DATABASE EMP1

dropping, or removing, a table from a database

DROP TABLE EMPLOYEE

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