Sql mutations: Difference between revisions

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= Tables =
<blockquote>
== CREATE ==
<blockquote>
<syntaxhighlight lang="MySQL">
CREATE TABLE users (
  id        INT NOT NULL PRIMARY KEY AUTO_INCREMENT,
  first_name VARCHAR(10),
  last_name  VARCHAR(10),
  age        TINYINT
);
</syntaxhighlight>
</blockquote><!-- CREATE -->
= ALTER =
<blockquote>
<syntaxhighlight lang="MySQL">
ALTER TABLE users RENAME TO employees;
</syntaxhighlight>
</blockquote><!-- ALTER -->
== DROP ==
<blockquote>
<syntaxhighlight lang="MySQL">
DROP TABLE users;
</syntaxhighlight>
</blockquote><!-- DROP -->
</blockquote><!-- Tables -->
= Rows =
= Rows =
<blockquote>
<blockquote>

Revision as of 18:06, 19 September 2021

Tables

CREATE

CREATE TABLE users (
  id         INT NOT NULL PRIMARY KEY AUTO_INCREMENT,
  first_name VARCHAR(10),
  last_name  VARCHAR(10),
  age        TINYINT
);

ALTER

ALTER TABLE users RENAME TO employees;

DROP

DROP TABLE users;

Rows

INSERT

Add rows to a table.

Insert multiple rows.

#           table (          columns                        )
#             |                 |
INSERT INTO tasks(subject, start_date, end_date, description)
VALUES ('Task 1','2010-01-01','2010-01-02','Description 1'),
       ('Task 2','2010-01-01','2010-01-02','Description 2'),
       ('Task 3','2010-01-01','2010-01-02','Description 3');

Insert row if match does not exist.

# Add 'Rupert' to users if does not exist
INSERT INTO users (name, address, tele)
SELECT * FROM (SELECT 'Rupert', 'Somewhere', '022') AS tmp
WHERE NOT EXISTS (SELECT name FROM users WHERE name = 'Rupert') LIMIT 1;

UPDATE

Update an existing row.

UPDATE users
set    email = "user@domain.com"
WHERE  id = 190;

DELETE

Delete an existing row.

DELETE FROM users
WHERE id = 100;