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Updating plsql

If there is any type mismatch, variable assignments and comparisons may not work the way you expect.

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WHERE CURRENT OF & FOR UPDATE The WHERE CURRENT OF clause is used in some UPDATE and DELETE statements.

Another Example of WHERE CURRENT OF Go through all Maths students and set all GPA’s under 4.0 to 4.0!

DECLARE this Student Student%ROWTYPE; CURSOR Maths_Student IS SELECT * FROM Student WHERE SID IN (SELECT SID FROM Take WHERE CID = ’CS145’) FOR UPDATE; BEGIN OPEN Maths_Student; LOOP FETCH Maths_Student INTO this Student; EXIT WHEN (Maths_Student%NOTFOUND); IF (this Student.

Note: The material on triggers that was formerly in this document has been moved to A New Document on Constraints and Triggers. PL/SQL extends SQL by adding constructs found in procedural languages, resulting in a structural language that is more powerful than SQL. All PL/SQL programs are made up of blocks, which can be nested within each other.

Typically, each block performs a logical action in he program.

The simplest form of program has some declarations followed by an executable section consisting of one or more of the SQL statements with which we are familiar.

The major nuance is that the form of the statement in PL/SQL only works if the result of the query contains a single tuple.

Inside a cursor loop, WHERE CURRENT OF allows the current row to be directly updated.

When the session opens a cursor with the FOR UPDATE clause, all rows in the return set will hold row-level exclusive locks.

The syntax of using the WHERE CURRENT OF clause in UPDATE and DELETE statements follows: WHERE [CURRENT OF cursor_name | search_condition] The following example opens a cursor for employees and updates the commission, if there is no commission assigned based on the salary level.