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Although PL/SQL's general syntax formerly used to resemble that of Ada or Pascal, there were many improvements that mainly include the Java embedding code [4] and the object-oriented syntax [5] inside the SQL. The mixing and embedding of triggers and stored procedures was one of the breakthrough points up to support the use of PL/SQL in a OO ...
PL/SQL refers to a class as an "Abstract Data Type" (ADT) or "User Defined Type" (UDT), and defines it as an Oracle SQL data-type as opposed to a PL/SQL user-defined type, allowing its use in both the Oracle SQL Engine and the Oracle PL/SQL engine. The constructor and methods of an Abstract Data Type are written in PL/SQL.
Oracle SQL Developer worked with IBM Db2, Microsoft Access, Microsoft SQL Server, MySQL, Sybase Adaptive Server, Amazon Redshift and Teradata databases. [4] Oracle SQL Developer supports automatic tabs, code insight, bracket matching and syntax coloring for PL/SQL. Future versions of Oracle SQL Developer will use Visual Studio Code. [1]
The DUAL table is a special one-row, one-column table present by default in Oracle and other database installations. In Oracle, the table has a single VARCHAR2(1) column called DUMMY that has a value of 'X'. It is suitable for use in selecting a pseudo column such as SYSDATE or USER.
In addition to triggers that fire (and execute PL/SQL code) when data is modified, Oracle 10g supports triggers that fire when schema-level objects (that is, tables) are modified and when user logon or logoff events occur.
So if two tables are T1 and T2, SELECT * FROM T1, T2 will result in every combination of T1 rows with every T2 rows. E.g., if T1 has 3 rows and T2 has 5 rows, then 15 rows will result. Although not in standard, most DBMS allows using a select clause without a table by pretending that an imaginary table with one row is used.
PL/SQL Developer, an Integrated Development Environment for developing software in the Oracle database environment, [2] focuses on the development of PL/SQL stored-program units. Allround Automations, based in Enschede in the Netherlands , markets the software.
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. CTEs can be thought of as alternatives to derived tables ( subquery ), views , and inline user-defined functions.