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Cursor-for loops automatically open a cursor, read in their data and close the cursor again. As an alternative, the PL/SQL programmer can pre-define the cursor's SELECT-statement in advance to (for example) allow re-use or make the code more understandable (especially useful in the case of long or complex queries).
FETCH ABSOLUTE n FROM cursor_name FETCH RELATIVE n FROM cursor_name; Scrollable cursors can potentially access the same row in the result set multiple times. Thus, data modifications (insert, update, delete operations) from other transactions could affect the result set. A cursor can be SENSITIVE or INSENSITIVE to such data modifications.
Stored procedures may also contain declared variables for processing data and cursors that allow it to loop through multiple rows in a table. Stored-procedure flow-control statements typically include IF , WHILE , LOOP , REPEAT , and CASE statements, and more.
A common table expression, or CTE, (in SQL) is a temporary named result set, derived from a simple query and defined within the execution scope of a SELECT, INSERT, UPDATE, or DELETE statement.
In computing, the Oracle Call Interface (OCI) consists of a set of C-language software APIs which provide an interface to the Oracle database.. OCI offers a procedural API for not only performing certain database administration tasks (such as system startup and shutdown), but also for using PL/SQL or SQL to query, access, and manipulate data.
Like Oracle's PL/SQL or Microsoft's Transact-SQL, DAL is essentially an extended version of SQL supporting basic query functionality and adding clean syntax for cursor operations, logic, and loops. When sent a command, early versions of Apple's DAL interpreter broke down the statement and re-built it into subqueries for the underlying data sources.
MS SQL Server supports trigger for DML and DDL statement plus special trigger "logon". The scope of DDL triggers can be a database (CREATE TRIGGER name ON DATABASE ...) or the entire SQL Server instance (CREATE TRIGGER name ON ALL SERVER). When you use the entire instance, you can capture all events executed on commands that have server-level scop
Though database systems use SQL, they also have their own additional proprietary extensions that are usually only used on their system. For example, Microsoft SQL server uses Transact-SQL (T-SQL), which is an extension of SQL. Similarly, Oracle uses PL-SQL, which an Oracle-specific SQL extension.