MySQL - most used commands with examples
09/28/2022 12:00 AM
by Publisher
in Db
Contents
To check MySQL status run:
To connect to a MySQL server running on the same host:
To connect to a MySQL server running on the remote host db1.example.com:
mysql -u username -p -h db1.example.com
To create a database:
mysql> CREATE DATABASE [databasename];
List all databases on the current MySQL server:
Connect to a database to start working with it:
To delete database:
mysql> DROP DATABASE [database name];
List all tables in a current database:
Display table’s columns types and descriptions:
mysql> DESCRIBE [table name];
Display all table’s content:
mysql> SELECT * FROM [table name];
Display overall table’s lines:
mysql> SELECT COUNT(*) FROM [table name];
Count columns in a table:
mysql> SELECT SUM(*) FROM [table name];
Drop column from a table:
mysql> alter table [table name] DROP INDEX [column name];
Delete the whole table:
mysql> DROP TABLE [table name];
Add a new column to the table:
mysql> ALTER TABLE [table name] ADD COLUMN [new column name] varchar (20);
Change the column’s name:
mysql> ALTER TABLE [table name] CHANGE [old column name] [new column name] varchar (50);
Create a column with an unique name to avoid duplicates:
mysql> ALTER TABLE [table name] ADD UNIQUE ([column name]);
Change the column’s size:
mysql> ALTER TABLE [table name] MODIFY [column name] VARCHAR(3);
Display all table’s content:
mysql> SELECT * FROM [table name];
Display all columns and their content from a table:
mysql> SHOW COLUMNS FROM [table name];
Display all records from a table with the “whatever“:
mysql> SELECT * FROM [table name] WHERE [field name] = "whatever";
Find all records with the “Bob” in the name column and “3444444 in the phone_number column:
mysql> SELECT * FROM [table name] WHERE name = "Bob" AND phone_number = '3444444';
Find all records withOUT the “Bob” in the name column and “3444444 in thephone_numbercolumn sorting them by the phone_number column:
mysql> SELECT * FROM [table name] WHERE name != "Bob" AND phone_number = '3444444' order by phone_number;
Display all records starting from the ‘tom‘ and ‘123′ phone in a specific table:
mysql> SELECT * FROM [table name] WHERE name like "Tom%" AND phone_number = '123';
Display all records starting from the ‘tom‘ and ‘123′ phone in a specific table limiting results from 1 to 9:
mysql> SELECT * FROM [table name] WHERE name like "Tom%" AND phone_number = '123' limit 1,9;
Show all unique records:
mysql> SELECT DISTINCT [column name] FROM [table name];
Display selected records sorting the by decreasing order:
mysql> SELECT [col1],[col2] FROM [table name] ORDER BY [col2] DESC;
You can use the regex (“REGEXP BINARY”) in your filters.
For example to find all records starting with the “A” using case-independent regex search:
mysql> SELECT * FROM [table name] WHERE rec RLIKE "^a";
To load data from a CSV file into a table:
mysql> LOAD DATA INFILE '/tmp/filename.csv' replace INTO TABLE [table name] FIELDS TERMINATED BY ',' LINES TERMINATED BY 'n' (field1,field2,field3);
Adding a new user: connect to a server as root, connect to a database, adding a user, updating privileges:
mysql -u root -p
mysql> USE mysql;
mysql> INSERT INTO user (Host,User,Password) VALUES('%','username', PASSWORD('password'));
mysql> flush privileges;
To change a user’s password on a remote host db1.example.org using the mysqladmin tool:
mysqladmin -u username -h db1.example.org -p password 'new-password'
To change user’s password from the MySQL CLI:
mysql> SET PASSWORD FOR 'user'@'hostname' = PASSWORD('passwordhere');
mysql> flush privileges;
To reset MySQL root’s password: stop the server, start it without privileges table, log in as root, set new password, exit and start MySQL in the normal way:
systemctl stop mysql
mysqld_safe --skip-grant-tables &
mysql -u root
mysql> use mysql;
mysql> update user set password=PASSWORD("newrootpassword") where User='root';
mysql> flush privileges;
mysql> quit
systemctl start mysql
To update root‘s password: using mysqladmin:
mysqladmin -u root -p oldpassword newpassword
Grant permissions for remote login from the localhost host with the passwd password:
mysql -u root -p
mysql> use mysql;
mysql> grant usage on *.* to tom@localhost identified by 'passwd';
mysql> flush privileges;
Grant specific permissions for user:
mysql> use mysql;
mysql> INSERT INTO db (Host,Db,User,Select_priv,Insert_priv,Update_priv,Delete_priv,Create_priv,Drop_priv) VALUES ('%','databasename','username','Y','Y','Y','Y','Y','N');
mysql> flush privileges;
Or just grant everything:
mysql> grant all privileges on databasename.* to username@localhost;
mysql> flush privileges;
Setting specific permissions for a user per specific table:
mysql> UPDATE [table name] SET Select_priv = 'Y',Insert_priv = 'Y',Update_priv = 'Y' where [field name] = 'user';
Do not forget update privileges:
Create a backup (dump) from all databases into the alldatabases.sql file:
mysqldump -u root -p password --opt >/tmp/alldatabases.sql
Create a backup (dump) from a database with the databasename name into the databasename.sql file:
mysqldump -u username -p password --databases databasename >/tmp/databasename.sql
Create one table’s backup into the databasename.tablename.sql file:
mysqldump -c -u username -p password databasename tablename > /tmp/databasename.tablename.sql
To restore database(s) or table(s) from a backup:
mysql -u username -p password databasename < /tmp/databasename.sql
italic: columns name;
In CAPITAL letters: types and attributes for columns;
in (brackets) – column’s values.
Example 1:
mysql> 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));
Example 2:
mysql> create table [table name] (personid INT(50) NOT NULL AUTO_INCREMENT PRIMARY KEY, firstname VARCHAR(35), middlename VARCHAR(50), lastname VARCHAR(50) default 'bato');
