Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
Using LOCK TABLE
You use the LOCK TABLE statement to lock the whole database tables in the specified lock mode so that you can share or deny the access to them. For illustration, the statement below locks the emp table in the row share mode. The Row share locks permit concurrent access to the table; they avoid other users from locking the whole table for the restricted use. The Table locks are released when your transaction issues a commit or rollback.
LOCK TABLE emp IN ROW SHARE MODE NOWAIT;
The lock mode determines what other locks can be located on the table. For illustration, many users can obtain the row share locks on the table at the same time, excluding only one user at a time can obtain an exclusive lock. Whereas one user has an exclusive lock on the table, no other users can insert, delete, and update rows in that table.
Using NOT NULL Besides assigning an initial value, the declarations can impose the NOT NULL constraint, as the example below shows: acct_id INTEGER(4) NOT NULL := 9999; You ca
Use of Table Comparisons - SQL Table comparisons where it is noted that although table expressions cannot be compared, we have TABLE (t) to convert a table expression t into
SQL Functions The PL/SQL uses all the SQL functions involving the following aggregate functions that summarize the whole columns of the Oracle data: GROUPING, AVG, COUNT, STDDE
Number Types The Number types permit you to store the numeric data (real numbers, integers, and floating-point numbers), show quantities, and do computations. BINARY_INTEG
Avoiding Collection Exceptions In many cases, if you reference a nonexistent collection element, then PL/SQL raises a predefined exception. Consider the illustration shown b
Main features of PL/SQL A good way to get familiar with PL/SQL is to look at a sample program. The below program processes an order for tennis rackets. At first, it declares a
Table Comparison - SQL The following definitions for relation comparisons: Let r1 and r2 be relations having the same heading. Then: r1 ⊆ r2 is true if every tuple of r1
DELETE Statement The DELETE statement eliminates whole rows of data from the specified table or view. Syntax:
Wrapping and unwrapping in SQL Operators WRAP and UNWRAP in connection with attributes whose declared types are tuple types. Example shows how extension and projection can be
At times, customers make mistakes in submitting their orders and call to cancel the order. Brewbean’s wants to create a trigger that automatically updates the stock level of all pr
Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd