Handy MySQL Commands
Description
Command
To login (from unix shell) use -h only if needed.
[mysql dir]/bin/mysql -h hostname -u root -p
Create a database on the sql server.
create database [databasename];
List all databases on the sql server.
show databases;
Switch to a database.
use [db name];
To see all the tables in the db.
show tables;
To see database's field formats.
describe [table name];
To delete a db.
drop database [database name];
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 "whatever".
SELECT * FROM [table name] WHERE [field name] = "whatever";
Show all records containing the name "Bob" AND the phone number
'3444444'.
SELECT * FROM [table name] WHERE name = "Bob" AND phone_number = '3444444';
Show all records not containing the name "Bob" AND the phone number '3444444' order by the phone_number field.
SELECT * FROM [table name] WHERE name != "Bob" AND phone_number = '3444444' order by phone_number;
Show all records starting with the letters 'bob' AND the phone number
'3444444'.
SELECT * FROM [table name] WHERE name like "Bob%" AND phone_number = '3444444';
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 [col1],[col2] FROM [table name] ORDER BY [col2] DESC;
Count rows.
SELECT COUNT(*) 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;
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]/bin/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');
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 ('%','db','user','Y','Y','Y','Y','Y','N');
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] = 'whatever';
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(3);
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);
Dump all databases for backup. Backup file is sql commands to recreate all db's.
[mysql dir]/bin/mysqldump -u root -ppassword --opt >/tmp/alldatabases.sql
Dump one database for backup.
[mysql dir]/bin/mysqldump -u username -ppassword --databases databasename >/tmp/databasename.sql
Dump a table from a database.
[mysql dir]/bin/mysqldump -c -u username -ppassword databasename tablename > /tmp/databasename.tablename.sql
Restore database (or database table) from backup.
[mysql dir]/bin/mysql -u username -ppassword databasename < /tmp/databasename.sql
Create Table Example 1.
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));
Create Table Example 2.
create table [table name] (personid int(50) not null auto_increment primary key,firstname varchar(35),middlename varchar(50),lastname varchar(50) default 'bato');
Categories: Table, View, & Sequence DDL Describes the columns in a view (or table). DESCRIBE can be abbreviated to DESC. See also:DROP VIEW ,
ALTER VIEW , CREATE VIEW , SHOW VIEWS DESCRIBE TABLE
Syntax¶Parameters¶nameSpecifies the identifier for the view to describe. If the identifier contains spaces or special characters, the
entire string must be enclosed in double quotes. Identifiers enclosed in double quotes are also case-sensitive. Usage Notes¶The command output does not include the view definition. Instead, use SHOW
VIEWS. DESC VIEW and DESCRIBE TABLE are interchangeable. Either command retrieves the details for the table or view that matches the criteria in the statement. The output returns a POLICY NAME column to indicate the Column-level Security masking
policy set on the column. If a masking policy is not set on the column or if the Snowflake account is not Enterprise Edition or higher, Snowflake returns NULL.
Examples¶Example setup: CREATE VIEW emp_view AS SELECT id "Employee Number", lname "Last Name", location "Home Base" FROM emp;
Describe the view: DESC VIEW emp_view;
+-----------------+--------------+--------+-------+---------+-------------+------------+-------+------------+---------+-------------+
| name | type | kind | null? | default | primary key | unique key | check | expression | comment | policy name |
|-----------------+--------------+--------+-------+---------+-------------+------------+-------+------------+---------+-------------+
| Employee Number | NUMBER(38,0) | COLUMN | Y | NULL | N | N | NULL | NULL | NULL | NULL |
| Last Name | VARCHAR(50) | COLUMN | Y | NULL | N | N | NULL | NULL | NULL | NULL |
| Home Base | VARCHAR(100) | COLUMN | Y | NULL | N | N | NULL | NULL | NULL | NULL |
+-----------------+--------------+--------+-------+---------+-------------+------------+-------+------------+---------+-------------+
What does describe command used for?
The DESCRIBE command displays metadata about the columns, indexes, and data partitions of tables or views. This command can also display metadata about the output of SELECT, CALL, or XQuery statements.
Which command is use to describe the table?
Since in database we have tables, that's why we use DESCRIBE or DESC(both are same) command to describe the structure of a table. Syntax: DESCRIBE one; OR DESC one; Note : We can use either DESCRIBE or DESC(both are Case Insensitive).
Which command is used to view data inside the table?
Answer : SHOW TABLES; command is used to view the list of tables in a database.
How do you view data in a table?
To view table data:. In SQL Developer, search for a table as described in "Viewing Tables". ... . Select the table that contains the data. ... . In the object pane, click the Data subtab. ... . (Optional) Click a column name to sort the data by that column.. (Optional) Click the SQL subtab to view the SQL statement that defines the table.. | 
