basic-sql-operations.md

title	summary	aliases
Explore SQL with TiDB	Learn about the basic SQL statements for the TiDB database.	/docs/dev/basic-sql-operations/ /docs/dev/how-to/get-started/explore-sql/

Explore SQL with TiDB

TiDB is compatible with MySQL, you can use MySQL statements directly in most of the cases. For unsupported features, see Compatibility with MySQL.

To experiment with SQL and test out TiDB compatibility with MySQL queries, you can run TiDB directly in your web browser without installing it. You can also first deploy a TiDB cluster and then run SQL statements in it.

This page walks you through the basic TiDB SQL statements such as DDL, DML and CRUD operations. For a complete list of TiDB statements, see TiDB SQL Syntax Diagram.

Category

SQL is divided into the following 4 types according to their functions:

• DDL (Data Definition Language): It is used to define database objects, including databases, tables, views, and indexes.

• DML (Data Manipulation Language): It is used to manipulate application related records.

• DQL (Data Query Language): It is used to query the records after conditional filtering.

• DCL (Data Control Language): It is used to define access privileges and security levels.

Common DDL features are creating, modifying, and deleting objects (such as tables and indexes). The corresponding commands are CREATE, ALTER, and DROP.

Show, create and drop a database

A database in TiDB can be considered as a collection of objects such as tables and indexes.

To show the list of databases, use the SHOW DATABASES statement:

{{< copyable "sql" >}}

SHOW DATABASES;

To use the database named mysql, use the following statement:

{{< copyable "sql" >}}

USE mysql;

To show all the tables in a database, use the SHOW TABLES statement:

{{< copyable "sql" >}}

SHOW TABLES FROM mysql;

To create a database, use the CREATE DATABASE statement:

{{< copyable "sql" >}}

CREATE DATABASE db_name [options];

To create a database named samp_db, use the following statement:

{{< copyable "sql" >}}

CREATE DATABASE IF NOT EXISTS samp_db;

Add IF NOT EXISTS to prevent an error if the database exists.

To delete a database, use the DROP DATABASE statement:

{{< copyable "sql" >}}

DROP DATABASE samp_db;

Create, show, and drop a table

To create a table, use the CREATE TABLE statement:

{{< copyable "sql" >}}

CREATE TABLE table_name column_name data_type constraint;

For example, to create a table named person which includes fields such as number, name, and birthday, use the following statement:

{{< copyable "sql" >}}

CREATE TABLE person (
    id INT(11),
    name VARCHAR(255),
    birthday DATE
    );

To view the statement that creates the table (DDL), use the SHOW CREATE statement:

{{< copyable "sql" >}}

SHOW CREATE table person;

To delete a table, use the DROP TABLE statement:

{{< copyable "sql" >}}

DROP TABLE person;

Create, show, and drop an index

Indexes are used to speed up queries on indexed columns. To create an index for the column whose value is not unique, use the CREATE INDEX statement:

{{< copyable "sql" >}}

CREATE INDEX person_id ON person (id);

Or use the ALTER TABLE statement:

{{< copyable "sql" >}}

ALTER TABLE person ADD INDEX person_id (id);

To create a unique index for the column whose value is unique, use the CREATE UNIQUE INDEX statement:

{{< copyable "sql" >}}

CREATE UNIQUE INDEX person_unique_id ON person (id);

Or use the ALTER TABLE statement:

{{< copyable "sql" >}}

ALTER TABLE person ADD UNIQUE person_unique_id (id);

To show all the indexes in a table, use the SHOW INDEX statement:

{{< copyable "sql" >}}

SHOW INDEX FROM person;

To delete an index, use the DROP INDEX or ALTER TABLE statement. DROP INDEX can be nested in ALTER TABLE:

{{< copyable "sql" >}}

DROP INDEX person_id ON person;

{{< copyable "sql" >}}

ALTER TABLE person DROP INDEX person_unique_id;

Note:

DDL operations are not transactions. You don't need to run a COMMIT statement when executing DDL operations.

Insert, update, and delete data

Common DML features are adding, modifying, and deleting table records. The corresponding commands are INSERT, UPDATE, and DELETE.

To insert data into a table, use the INSERT statement:

{{< copyable "sql" >}}

INSERT INTO person VALUES(1,'tom','20170912');

To insert a record containing data of some fields into a table, use the INSERT statement:

{{< copyable "sql" >}}

INSERT INTO person(id,name) VALUES('2','bob');

To update some fields of a record in a table, use the UPDATE statement:

{{< copyable "sql" >}}

UPDATE person SET birthday='20180808' WHERE id=2;

To delete the data in a table, use the DELETE statement:

{{< copyable "sql" >}}

DELETE FROM person WHERE id=2;

Note:

The UPDATE and DELETE statements without the WHERE clause as a filter operate on the entire table.

Query data

DQL is used to retrieve the desired data rows from a table or multiple tables.

To view the data in a table, use the SELECT statement:

{{< copyable "sql" >}}

SELECT * FROM person;

To query a specific column, add the column name after the SELECT keyword:

{{< copyable "sql" >}}

SELECT name FROM person;
+------+
| name |
+------+
| tom  |
+------+

Use the WHERE clause to filter all records that match the conditions and then return the result:

{{< copyable "sql" >}}

SELECT * FROM person where id<5;

Create, authorize, and delete a user

DCL are usually used to create or delete users, and manage user privileges.

To create a user, use the CREATE USER statement. The following example creates a user named tiuser with the password 123456:

{{< copyable "sql" >}}

CREATE USER 'tiuser'@'localhost' IDENTIFIED BY '123456';

To grant tiuser the privilege to retrieve the tables in the samp_db database:

{{< copyable "sql" >}}

GRANT SELECT ON samp_db.* TO 'tiuser'@'localhost';

To check the privileges of tiuser:

{{< copyable "sql" >}}

SHOW GRANTS for tiuser@localhost;

To delete tiuser:

{{< copyable "sql" >}}

DROP USER 'tiuser'@'localhost';