Software Developer

MySQL Command Line Cheat Sheet

These are my most often-used MySQL commands and queries.

Connect to MySQL on the command line (replace USERNAME with your own):

mysql -u USERNAME -p

(You will then be prompted to enter your MySQL password.)

MySQL Databases

List all databases on the command line:

mysql> SHOW DATABASES;

Create a database on the command line:

mysql> CREATE DATABASE database_name CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;

Replace database_name, above, with your name of choice.

Delete a database:

mysql> drop database database_name;

Replace database_name, above, with the actual name of your database.

Use (or select) a database:

mysql> USE database_name; 

Check which database is currently selected:

mysql> SELECT DATABASE();

Backing up a database on the command line with mysqldump:

$ mysqldump --opt -u username -p database > database_backup.sql

(Use ‘mysqldump --opt --all-databases > all_backup.sql‘ to backup everything.)

Import a .sql database file into MySQL on the command line:

mysql -u root -p database_name < /home/path/to/some_database_file.sql

(Replace “root” with your MySQL user name, if needed.)

MySQL Users

List all MySQL users in a database. This shows a table of each MySQL user with the host, username, and password:

mysql> select host, user, password from mysql.user;

Delete a MySQL user:

mysql> DROP USER 'username'@'host';

Create a MySQL user and set the user’s password:

CREATE USER username@host;
SET PASSWORD FOR username@host= PASSWORD("thePassword");

Grant database access to a MySQL user:

GRANT ALL PRIVILEGES ON database_name.* TO username@host IDENTIFIED BY 'thePassword';
FLUSH PRIVILEGES;

MySQL Tables

List all tables of a MySQL database on the command line:

mysql> SHOW TABLES;

Describing the format of a table:

mysql> DESCRIBE table_name;

Replace table_name, above, with the actual name of your table.

Create a table on the command line:

mysql> CREATE TABLE table_name (field1_name TYPE(SIZE), field2_name TYPE(SIZE));

Example:

mysql> CREATE TABLE pet (name VARCHAR(20), sex CHAR(1), birth DATE);

Delete a table (aka Drop a table):

mysql> DROP TABLE table_name;

Replace table_name, above, with the actual name of the table you want to remove.

Delete all rows from a table, while leaving the table in tact:

mysql> TRUNCATE TABLE table_name;

Show all indexes (and keys) of a table:

mysql> SHOW INDEX FROM table_name;

Add a PRIMARY KEY to a table, assigning an existing column as the PRIMARY KEY. The bigint(20) NOT NULL part will vary according the attributes of your column:

mysql> ALTER TABLE table_name MODIFY COLUMN column_name bigint(20) NOT NULL PRIMARY KEY;

Delete a PRIMARY KEY from a table. This is done in a different way than deleting a regular index.

mysql> ALTER TABLE table_name DROP PRIMARY KEY;

Delete an index or key from a table:

mysql> DROP INDEX index_key_name ON table_name;

Create an index on a table:

mysql> CREATE INDEX index_key_name ON table_name (col_name);

Create an index, sorted in descending order. The DESC order only works in MySQL version 8+.

mysql> CREATE INDEX index_key_name ON table_name (col_name DESC);

Create an index on multiple columns:

mysql> CREATE INDEX index_col1_col2 ON table_name (col1, col2);

mysql> CREATE INDEX index_col1_col2 ON table_name (col1 DESC, col2);

Remove a row based on the value of a field (column) in a table:

mysql> DELETE FROM table_name WHERE field_name = 'whatever'; 

Replace table_name, above, with the actual name of your table. Replace field_name, above, with the actual name of your field. Replace ‘whatever’ with the value you’re searching for.

Selecting from tables

To run a SELECT query from the command line, type:

mysql> SELECT * FROM TABLE_NAME WHERE FIELD_NAME = "field_value";

Retrieving information from a table (general):

mysql> SELECT from_columns FROM table WHERE conditions;

Retrieve all rows from a MySQL table:

mysql> SELECT * FROM table;

Retrieve some rows, those with a field that has a specified value:

mysql> SELECT * FROM table WHERE field_name = "value";

Retrieve table rows based on multiple critera:

SELECT * FROM table WHERE field1 = "value1" AND field2 = "value2";

Update a value for a row that has another value set to a specified value:

mysql> UPDATE TABLE SET column_1_name = "new_value" WHERE column_2_name = "value";

To UPDATE a certain field value (dependent on the current/old value) in a MySQL database from the command line, type:

mysql> UPDATE table_name SET field_name = "new_value" WHERE field_name = "old_value";

To UPDATE a certain field value, regardless of the current value, just use:

mysql> UPDATE table_name SET field_name = "new_value";

Replace a string in a MySQL table. The WHERE clause is not necessary, but it can speed up the query in a very large table:

UPDATE table_name
SET field_name = REPLACE(field_name, 'old string to be replaced', 'new string')
WHERE field_name LIKE '%old string to be replaced%';

Load tab-delimited data into a table:

mysql> LOAD DATA LOCAL INFILE "infile.txt" INTO TABLE table_name;

(Use n for NULL)

Inserting one row at a time:

mysql> INSERT INTO table_name VALUES ('MyName', 'MyOwner', '2002-08-31');

(Use NULL for NULL)

Reloading a new data set into existing table:

mysql> SET AUTOCOMMIT=1; # used for quick recreation of table
mysql> DELETE FROM pet;
mysql> LOAD DATA LOCAL INFILE "infile.txt" INTO TABLE table;

Selecting specific columns:

mysql> SELECT column_name FROM table;

Retrieving unique output records:

mysql> SELECT DISTINCT column_name FROM table;

Sorting:

mysql> SELECT col1, col2 FROM table ORDER BY col2;

Backwards: SELECT col1, col2 FROM table ORDER BY col2 DESC;

Date calculations:

mysql> SELECT CURRENT_DATE, (YEAR(CURRENT_DATE)-YEAR(date_col)) AS time_diff [FROM table];

MONTH(some_date) extracts the month value and DAYOFMONTH() extracts day.

Pattern Matching:

mysql> SELECT * FROM table WHERE rec LIKE "blah%";

(% is wildcard – arbitrary # of chars)
Find 5-char values: SELECT * FROM table WHERE rec like “_____”;
(_ is any single character)

Extended Regular Expression Matching:

mysql> SELECT * FROM table WHERE rec RLIKE "^b$";

(. for char, […] for char class, * for 0 or more instances
^ for beginning, {n} for repeat n times, and $ for end)
(RLIKE or REGEXP)
To force case-sensitivity, use “REGEXP BINARY”

Count all rows in a table:

mysql> SELECT COUNT(*) FROM table_name;

Selecting from multiple tables:

(Example)

mysql> SELECT pet.name, comment FROM pet, event WHERE pet.name = event.name;

(You can join a table to itself to compare by using ‘AS’)

Maximum value:

mysql> SELECT MAX(col_name) AS label FROM table;

Auto-incrementing rows:

mysql> CREATE TABLE table (number INT NOT NULL AUTO_INCREMENT, name CHAR(10) NOT NULL);
mysql> INSERT INTO table (name) VALUES ("tom"),("dick"),("harry");

Adding a column to an already-created table:

mysql> ALTER TABLE tbl ADD COLUMN [column_create syntax] AFTER col_name;

Removing a column:

mysql> ALTER TABLE tbl DROP COLUMN col;

Misc

Batch mode (feeding in a script):

$ mysql -u user -p < batch_file

(Use -t for nice table layout and -vvv for command echoing.)
Alternatively:

mysql> source batch_file;

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