1⟩ What is Date Functions?
Date Functions are ADD_MONTHS, LAST_DAY, NEXT_DAY, MONTHS_BETWEEN & SYSDATE.
SQL and PL/SQL
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“Explore the Structure Query Language (SQL) and PLSQL Interview Questions and Answers”
45 SQL And PL/SQL Questions And Answers
2⟩ What is NVL?
NVL : Null value function converts a null value to a non-null value for the purpose of evaluating an expression. Numeric Functions accept numeric I/P & return numeric values. They are MOD, SQRT, ROUND, TRUNC & POWER.
3⟩ What is SQL*Plus?
SQL*Plus is an application that recognizes & executes SQL commands & specialized SQL*Plus commands that can customize reports, provide help & edit facility & maintain system variables.
4⟩ What is the SQL?
SQL stands for Structure Query Language. SQL is an English like language consisting of commands to store, retrieve, maintain & regulate access to your database.
5⟩ What is SPOOL?
SPOOL command creates a print file of the report.
6⟩ What is COMPUTE?
command control computations on subsets created by the BREAK command.
7⟩ What is SET?
SET command changes the system variables affecting the report environment.
8⟩ What is BREAK?
BREAK command clarify reports by suppressing repeated values, skipping lines & allowing for controlled break points.
9⟩ What is SQL Integrity?
Assures database data and structures reflects all changes made to them in the correct sequence. Locks ensure data integrity and maximum concurrent access to data. Commit statement releases all locks. Types of locks are given below.
Data Locks protects data i.e. Table or Row lock.
Dictionary Locks protects the structure of database object i.e. ensures table's structure does not change for the duration of the transaction.
Internal Locks & Latches protects the internal database structures. They are automatic.
Exclusive Lock allows queries on locked table but no other activity is allowed.
Share Lock allows concurrent queries but prohibits updates to the locked tables.
Row Share allows concurrent access to the locked table but prohibits for a exclusive table lock.
Row Exclusive same as Row Share but prohibits locking in shared mode.
Shared Row Exclusive locks the whole table and allows users to look at rows in the table but prohibit others from locking the table in share or updating them.
Share Update are synonymous with Row Share.
10⟩ What is Consistency?
Consistency : Assures users that the data they are changing or viewing is not changed until the are thro' with it.
11⟩ What is COLUMN?
COLUMN command define column headings & format data values.
12⟩ What is TTITLE and BTITLE?
TTITLE & BTITLE are commands to control report headings & footers.
13⟩ What is Character Functions?
Character Functions are INITCAP, UPPER, LOWER, SUBSTR & LENGTH. Additional functions are GREATEST & LEAST. Group Functions returns results based upon groups of rows rather than one result per row, use group functions. They are AVG, COUNT, MAX, MIN & SUM.
14⟩ What is Locking?
Locking are mechanisms intended to prevent destructive interaction between users accessing data. Locks are used to achieve.
15⟩ What is Rollback?
Rollback causes work in the current transaction to be undone.
16⟩ What is Set Transaction?
Set Transaction is to establish properties for the current transaction.
17⟩ What is Savepoint?
Savepoint is a point within a particular transaction to which you may rollback without rolling back the entire transaction.
18⟩ What is Posting?
Posting is an event that writes Inserts, Updates & Deletes in the forms to the database but not committing these transactions to the database.
19⟩ What is Commit?
Commit is an event that attempts to make data in the database identical to the data in the form. It involves writing or posting data to the database and committing data to the database. Forms check the validity of the data in fields and records during a commit. Validity check are uniqueness, consistency and db restrictions.
20⟩ What is Transaction?
Transaction is defined as all changes made to the database between successive commits.
