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In addition to static SQL discussed in this chapter, PL/SQL also supports dynamic SQL, which enables you to execute SQL data definition, data control, and session control statements dynamically.
Implicit cursor is used for all other SQL statements (INSERT, UPDATE, DELETE, and single-row SELECT…INTO) • Actually PL/SQL engine takes care of the above four steps automatically) Drawbacks of Implicit Cursors • It is less efficient than an explicit cursor -- it performs minimum two fetches to see if it has more than one rows. However, there is no explicit cursor for UPDATE, DELETE, and INSERT statements.
is not declared SELECT * FROM employee; -- this is a static cursor • SELECT statement contains no INTO clause.
Here ‘emp_tbl’ in the table which contains records of all the employees. On every fetch statement, the pointer moves to the next row.
2) Accessing the records in the cursor: Once the cursor is created in the declaration section we can access the cursor in the execution section of the PL/SQL program. If you want to fetch after the last row, the program will throw an error.
When there is more than one row in a cursor we can use loops along with explicit cursor attributes to fetch all the records.
Points to remember while fetching a row: · We can fetch the rows in a cursor to a PL/SQL Record or a list of variables created in the PL/SQL Block.
• Cursor is a handle (or pointer), to the context area.
PL/SQL program can control the context area using Cursor. • SELECT statement should return only one row at a time in previous PL/SQL programs. • We use the idea of Cursor to handle the above problem. Even if your query returns only a single row, you might still decide to use an explicit cursor.
You can manipulate Oracle data flexibly and safely because PL/SQL fully supports all SQL data manipulation statements (except ), transaction control statements, functions, pseudocolumns, and operators.Tags: Adult Dating, affair dating, sex dating