The YugabyteDB SQL language
This page describes the categorization scheme for the SQL statements and links to lists of the statements that fall into each category. It also describes notions, like the WITH
clause, that need careful explanation and have applicability across two or more statement kinds.
Under construction.
Future versions of the YSQL documentation will explain further such common notions.Classification of SQL statements
Data definition language (DDL)
DDL statements define the structures in a database, change their definitions, and remove them by using CREATE
, ALTER
, and DROP
commands respectively.
Data manipulation language (DML)
DML statements query and modify the contents of a database.
Data control language (DCL)
DCL statements protect the definitions of database objects and the data the tables store using a regime of rules and privileges that control the scope and power of DDL and DML statements.
Transaction control language (TCL)
TCL statements manage transactions of operations on the database.
Session and system control
Statements in this class allow database parameters to be set at the session or the system level.
Performance control
Statements in this class support the preparation of SQL statements, and their subsequent execution, to allow a more efficient execution by binding actual arguments to placeholders in a SQL statement that is compiled just once, per session, rather than every time actual arguments are presented. The canonical example of this feature is provided by the actual arguments that a WHERE
clause restriction uses or the actual values than an INSERT
statement will use.
In the performance control class, the EXPLAIN
statement shows what access methods a DML statement will use and (for statements with joins) the join order and method.
The WITH clause
The WITH
clause (sometimes known as the common table expression) can be used as part of a SELECT
statement, an INSERT
statement, an UPDATE
statement, or a DELETE
statement. For this reason, the functionality is described in a dedicated section.