What is context area in SQL?

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Oracle creates a memory area, known as the context area, for processing an SQL statement, which contains all the information needed for processing the statement; for example, the number of rows processed, etc. A cursor is a pointer to this context area. PL/SQL controls the context area through a cursor.

What is cursor context area?

When an SQL statement is processed, Oracle creates a memory area known as context area. A cursor is a pointer to this context area. It contains all information needed for processing the statement. In PL/SQL, the context area is controlled by Cursor.

What is context in PL SQL?

Think of an application context as a global variable that holds information that is accessed during a database session. To set the values for a secure application context, you must create a PL/SQL package procedure that uses the DBMS_SESSION. SET_CONTEXT procedure.

What is cursor in Oracle SQL?

To execute a multi-row query, Oracle opens an unnamed work area that stores processing information. A cursor lets you name the work area, access the information, and process the rows individually. For more information, see "Querying Data with PL/SQL".

What is cursor explain with example?

Cursor is a Temporary Memory or Temporary Work Station. It is Allocated by Database Server at the Time of Performing DML(Data Manipulation Language) operations on Table by User. Cursors are used to store Database Tables. There are 2 types of Cursors: Implicit Cursors, and Explicit Cursors.

What is active data set in SQL?

The set of rows returned by a SQL query is called the result set. This result set is called Active Data Set because data in cursor is ready to undergo any kind of processing. The size of cursor is the same as the size required by the number of rows in Active Data Set. This size is constrained by the size of memory.

How do you print a statement in PL SQL?

execute immediate q'[select destination from temp_1 where cond1 =(:var1) and cond2 = (:var2) into dest]’ using sd(i),sid1(i); return dest; — or printline dbms_output. put_line(dest);

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What is Sys_context in Oracle 11g?

SYS_CONTEXT returns the value of parameter associated with the context namespace . You can use this function in both SQL and PL/SQL statements. For namespace and parameter , you can specify either a string or an expression that resolves to a string designating a namespace or an attribute.

What is userenv in Oracle?

USERENV is a legacy function that is retained for backward compatibility. Oracle recommends that you use the SYS_CONTEXT function with the built-in USERENV namespace for current functionality. See SYS_CONTEXT for more information. USERENV returns information about the current session.

How many rows can a cursor hold?

A cursor can be viewed as a pointer to one row in a set of rows. The cursor can only reference one row at a time, but can move to other rows of the result set as needed.

What is trigger in PL SQL?

A PL/SQL trigger is a named database object that encapsulates and defines a set of actions that are to be performed in response to an insert, update, or delete operation against a table. Triggers are created using the PL/SQL CREATE TRIGGER statement.

What is cursor in Python?

Cursor class is an instance using which you can invoke methods that execute SQLite statements, fetch data from the result sets of the queries. You can create Cursor object using the cursor() method of the Connection object/class.

What is cursor in Java?

A Cursor is a subclass of Object class and it can be defined as point or indicator on the screen. A Cursor is used to select the input from the system that the user operates with the mouse.

What is cursor in MySQL?

MySQL cursor is a kind of loop facility given to traverse in the result of SQL one by one. We can operate on every result by using the cursor in MySQL. Cursors are supported in stored procedures, functions, and triggers only. MySQL cursor is available from version 5 or greater.

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How do I run a cursor in Oracle?

How to use Explicit Cursor?
  1. DECLARE the cursor in the Declaration section.
  2. OPEN the cursor in the Execution Section.
  3. FETCH the data from the cursor into PL/SQL variables or records in the Execution Section.
  4. CLOSE the cursor in the Execution Section before you end the PL/SQL Block.
How to use Explicit Cursor?
  1. DECLARE the cursor in the Declaration section.
  2. OPEN the cursor in the Execution Section.
  3. FETCH the data from the cursor into PL/SQL variables or records in the Execution Section.
  4. CLOSE the cursor in the Execution Section before you end the PL/SQL Block.

How do I run a PL SQL program in MySQL workbench?

Text Editor
  1. Type your code in a text editor, like Notepad, Notepad+, or EditPlus, etc.
  2. Save the file with the . sql extension in the home directory.
  3. Launch the SQL*Plus command prompt from the directory where you created your PL/SQL file.
  4. Type @file_name at the SQL*Plus command prompt to execute your program.
Text Editor
  1. Type your code in a text editor, like Notepad, Notepad+, or EditPlus, etc.
  2. Save the file with the . sql extension in the home directory.
  3. Launch the SQL*Plus command prompt from the directory where you created your PL/SQL file.
  4. Type @file_name at the SQL*Plus command prompt to execute your program.

What is Oracle namespace?

A namespace defines a group of tables, within which all of the table names must be uniquely identified. This chapter describes namespaces and how to create and manage the namespaces in Oracle NoSQL Database. Namespaces permit you to do table privilege management as a group operation.

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What is userenv (‘ lang ‘) in Oracle?

USERENV is a legacy function that is retained for backward compatibility. Oracle recommends that you use the SYS_CONTEXT function with the built-in USERENV namespace for current functionality. See SYS_CONTEXT for more information. USERENV returns information about the current session.

What is Sys_context?

SYS_CONTEXT returns the value of parameter associated with the context namespace . You can use this function in both SQL and PL/SQL statements. For namespace and parameter , you can specify either a string or an expression that resolves to a string designating a namespace or an attribute.

How do you make a cursor?

To work with cursors you must use the following SQL statements: DECLARE CURSOR.
…
Cursors in SQL procedures
  1. Declare a cursor that defines a result set.
  2. Open the cursor to establish the result set.
  3. Fetch the data into local variables as needed from the cursor, one row at a time.
  4. Close the cursor when done.
To work with cursors you must use the following SQL statements: DECLARE CURSOR.
…
Cursors in SQL procedures
  1. Declare a cursor that defines a result set.
  2. Open the cursor to establish the result set.
  3. Fetch the data into local variables as needed from the cursor, one row at a time.
  4. Close the cursor when done.

How do I make a materialized view read only?

  1. 1.3.3.1 About Connecting to the Database with SQL*Plus.
  2. 1.3.3.2 Step 1: Open a Command Window.
  3. 1.3.3.3 Step 2: Set Operating System Environment Variables.
  4. 1.3.3.4 Step 3: Start SQL*Plus.
  5. 1.3.3.5 Step 4: Submit the SQL*Plus CONNECT Command. 1.3.3.5.1 Syntax of the SQL*Plus CONNECT Command.
  1. 1.3.3.1 About Connecting to the Database with SQL*Plus.
  2. 1.3.3.2 Step 1: Open a Command Window.
  3. 1.3.3.3 Step 2: Set Operating System Environment Variables.
  4. 1.3.3.4 Step 3: Start SQL*Plus.
  5. 1.3.3.5 Step 4: Submit the SQL*Plus CONNECT Command. 1.3.3.5.1 Syntax of the SQL*Plus CONNECT Command.

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