81⟩ In a Client/Server context, what does API (Application Programming Interface) refer to?
An API, in a Client/Server context, is a specification of a set of functions for communication between the client and the server.
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172 SQL Questions And Answers
82⟩ What are the various uses of database triggers?
Database triggers can be used to enforce business rules, to maintain derived values and perform value-based auditing.
83⟩ What are the disadvantages of the client/server model?
Heterogeneity of the system results in reduced reliablity. May not be suitable for all applications. Managing and tuning networks becomes difficult.
84⟩ What does the term downsizing refer to?
A host based application is re-engineered to run in smaller or LAN based environment.
85⟩ What is the first work of Client process?
A client process at first establishes connection with the Server.
86⟩ What are the three components of a client server model?
A Client,
A Server and
A Network/Communication software.
87⟩ How is a connection established by ODBC?
ODBC uses the description of the datasource available in the ODBC.INI file to load the required drivers to access that particular back end database.
88⟩ What are the two components of ODBC?
1. An ODBC manager/administrator and
2. ODBC driver.
89⟩ What is the difference between file server and a database server?
A file server just transfers all the data requested by all its client and the client processes the data while a database server runs the query and sends only the query output.
90⟩ Why is an event driven program referred to a passive program?
Because an event driven program is always waiting for something to happen before processing.
91⟩ What is the function of a ODBC Driver?
The ODBC Driver allows the developer to talk to the back end database.
92⟩ Most important DDL statements in SQL are
CREATE TABLE - creates a new database table
ALTER TABLE - alters (changes) a database table
DROP TABLE - deletes a database table
CREATE INDEX - creates an index (search key)
DROP INDEX - deletes an index
93⟩ SELECT statements
SELECT column_name(s) FROM table_name
SELECT DISTINCT column_name(s) FROM table_name
SELECT column FROM table WHERE column operator value
SELECT column FROM table WHERE column LIKE pattern
SELECT column,SUM(column) FROM table GROUP BY column
SELECT column,SUM(column) FROM table GROUP BY column HAVING SUM(column) condition value
Note that single quotes around text values and numeric values should not be enclosed in quotes. Double quotes may be acceptable in some databases.
94⟩ The Delete Statements
DELETE FROM table_name WHERE column_name = some_value
Delete All Rows:
DELETE FROM table_name or DELETE * FROM table_name
95⟩ Which system tables contain information on privileges granted and privileges obtained?
USER_TAB_PRIVS_MADE,
USER_TAB_PRIVS_RECD
96⟩ What is use of CASCADE CONSTRAINTS?
When this clause is used with the DROP command, a parent table can be dropped even when a child table exists.
97⟩ The INSERT INTO Statements
INSERT INTO table_name VALUES (value1, value2,....)
INSERT INTO table_name (column1, column2,...) VALUES (value1, value2,....)
98⟩ Which command displays the SQL command in the SQL buffer, and then executes it?
RUN.
99⟩ What will be the output of following query?
What will be the output of the following query?
SELECT DECODE(TRANSLATE('A','1234567890','1111111111'), '1','YES', 'NO' );?
NO. Explanation :
The query checks whether a given string is a numerical digit.
100⟩ What operator tests column for absence of data?
IS NULL operator.
