Friday, December 28, 2012

MySQL- basic commands in Mysql

To login from unix shell.
[mysql dir]/bin/mysql -h hostname -u root -p

*Note: use -h only if needed.
Create, List, Use and Delete Databases Commands

create database
This command is used to create a Database on the sql server..
Syntax: create [db name];

Eg:
create employees;

show databases
This command id used to list all databases on the sql server.
Syntax: show databases;

use database
This command is used to switch to a database.
Syntax: use [db name];

drop database
This command is used to delete a database.
Syntax: drop [db name];
Creating tables and working with MySQL

create tabe
This command is used to create tables in a database.

Eg:
CREATE TABLE [table name] (firstname VARCHAR(20), middleinitial VARCHAR(3), lastname VARCHAR(35),suffix VARCHAR(3),officeid VARCHAR(10),userid VARCHAR(15),username VARCHAR(8),email VARCHAR(35),phone VARCHAR(25), groups
VARCHAR(15),datestamp DATE,timestamp time,pgpemail VARCHAR(255));

show tables
This command is see all the tables in the database.

describe table
To see database's field formats.
describe [table name];

drop table
To delete a table.
drop table [table name];

Show all data in a table.
SELECT * FROM [table name];

Returns the columns and column information pertaining to the designated table.
show columns from [table name];

Show certain selected rows with the value "something".
SELECT * FROM [table name] WHERE [field name] = "something";

Show all records containing the name "Telson" AND the phone number '2255'.
SELECT * FROM [table name] WHERE name = "Telson" AND phone_number = '2255';

Show all records not containing the name "Telson" AND the phone number '2255' order by the phone_number field.
SELECT * FROM [table name] WHERE name != "Telson" AND phone_number = '2255' order by phone_number;

Show all records starting with the letters 'Tel' AND the phone number '2255'.
SELECT * FROM [table name] WHERE name like "Tel%" AND phone_number = '2255';

Use a regular expression to find records. Use "REGEXP BINARY" to force case-sensitivity. This finds any record beginning with a.
SELECT * FROM [table name] WHERE rec RLIKE "^a$";

Show unique records.
SELECT DISTINCT [column name] FROM [table name];

Show selected records sorted in an ascending (asc) or descending (desc).
SELECT [column1],[column2] FROM [table name] ORDER BY [column2] DESC;

Return number of rows.
SELECT COUNT(*) FROM [table name];

Sum column.
SELECT SUM(*) FROM [table name];

Join tables on common columns.
select lookup.illustrationid, lookup.personid,person.birthday from lookup left join person on lookup.personid=person.personid=statement to join birthday in person table with primary illustration id;
Creating Mysql databse Users and changing Password

Switch to the mysql db.

Create a new user.
INSERT INTO [table name] (Host,User,Password) VALUES('%','user',PASSWORD('password'));

Change a users password.(from unix shell).
[mysql dir] mysqladmin -u root -h hostname.blah.org -p password 'new-password'

Change a users password.(from MySQL prompt).
SET PASSWORD FOR 'user'@'hostname' = PASSWORD('passwordhere');

Allow the user "telson" to connect to the server from localhost using the password "passwd"
grant usage on *.* to telson@localhost identified by 'passwd';

Switch to mysql db.
Give user privilages for a db.
INSERT INTO [table name] (Host,Db,User,Select_priv,Insert_priv,Update_priv,Delete_priv,Create_priv,Drop_priv) VALUES ('%','databasename','username','Y','Y','Y','Y','Y','N');

or

grant all privileges on databasename.* to username@localhost;
Modifying and Updating tables in MySQL

To update info already in a table.
UPDATE [table name] SET Select_priv = 'Y',Insert_priv = 'Y',Update_priv = 'Y' where [field name] = 'user'; Delete a row(s) from a table.
DELETE from [table name] where [field name] = 'something';

Update database permissions/privilages.
FLUSH PRIVILEGES;

Delete a column.
alter table [table name] drop column [column name];

Add a new column to db.
alter table [table name] add column [new column name] varchar (20);

Change column name.
alter table [table name] change [old column name] [new column name] varchar (50);

Make a unique column so you get no dupes.
alter table [table name] add unique ([column name]);

Make a column bigger.
alter table [table name] modify [column name] VARCHAR(4);

Delete unique from table.
alter table [table name] drop index [colmn name];

Load a CSV file into a table.
LOAD DATA INFILE '/tmp/filename.csv' replace INTO TABLE [table name] FIELDS TERMINATED BY ',' LINES TERMINATED BY '\n' (field1,field2,field3);
Creating MySQL Database backup's and Restoring Databases

Dump all databases for backup. Backup file is sql commands to recreate all db's.
[mysql dir] mysqldump -u root -ppassword --opt >/tmp/alldatabases.sql

Dump one database for backup.
[mysql dir] mysqldump -u username -ppassword --databases databasename >/tmp/databasename.sql

Dump a table from a database.
[mysql dir] mysqldump -c -u username -ppassword databasename tablename > /tmp/databasename.tablename.sql

Restore database (or database table) from backup.
[mysql dir] mysql -u username -ppassword databasename < /tmp/databasename.sql

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