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: here

Statements in this class allow database parameters to be set at the session or the system level.

Performance control: here

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: here

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.