chapter-14-sql-commands.pdf

Chapter 14- SQL Commands II PUC, MDRPUC, Hassan
1 | P a g e Keerthi Kumar H M
Chapter-14
SQL COMMANDS
 What is SQL?
 Structured Query Language and it helps to make practice on SQL commands which provides
immediate results.
 SQL is Structured Query Language, which is a computer language for storing, manipulating and
retrieving data stored in relational database.
 SQL is the standard language for Relation Database System.
 All relational database management systems like MySQL, MS Access, and Oracle, Sybase,
Informix, and SQL Server use SQL as standard database language.
 Why SQL?
 Allows users to create and drop databases and tables.
 Allows users to describe the data.
 Allows users to define the data in database and manipulate that data.
 Allows users to access data in relational database management systems.
 Allows embedding within other languages using SQL modules, libraries & pre-compilers.
 Allows users to set permissions on tables, procedures, and views
 SQL Architecture:
 When you are executing an SQL command for any RDBMS, the system determines the best way
to carry out your request and SQL engine figures out how to interpret the task.
 There are various components included in the process.
 These components are:
o Query Dispatcher
o Optimization Engines
o Classic Query Engine
o SQL Query Engine, etc.
 Classic query engine handles all non-SQL queries
but SQL query engine won't handle logical files.
 Simple diagram showing SQL Architecture:

 SQL Commands:
 The standard SQL commands to interact with relational databases are CREATE, SELECT,
INSERT, UPDATE, DELETE and DROP.
 These commands can be classified into groups based on their nature:
 DDL - Data Definition Language:
 DDL defines the conceptual schema providing a link between the logical and the physical
structure of the database.
 The functions of the Data Definition Language (DDL) are:
1. DDL defines the physical characteristics of each record, filed in the record, field‟s data type,
field‟s length, field‟s logical name and also specify relationship among those records.
2. DDL describes the schema and subschema.
3. DDL indicate the keys of records.
4. DDL provides data security measures.
5. DDL provides for the logical and physical data independence.
 Few of the basic commands for DDL are:
Command Description
CREATE Creates a new table, a view of a table, or other object in database
ALTER Modifies an existing database object, such as a table.
DROP Deletes an entire table, a view of a table or other object in the database.
 DML - Data Manipulation Language:
 DML provides the data manipulation techniques like selection, insertion, deletion, updation,
modification, replacement, retrieval, sorting and display of data or records.
 DML facilitates use of relationship between the records.
 DML provides for independence of programming languages by supporting several high-level
programming languages like COBOL, PL/1 and C++.
 Few of the basic commands for DML are:
Command Description
SELECT Retrieves certain records from one or more tables
INSERT Creates a record
UPDATE Modifies records
DELETE Deletes records

 DCL - Data Control Language:
 These SQL commands are used for providing security to database objects.
 The different DCL commands are:
Command Description
GRANT Gives a privilege to user
REVOKE Takes back privileges granted from user
 TCL – Transaction Control Language:
 It includes commands to control the transactions in a database system.
 The commonly used commands are:
Command Description
COMMIT Make all the changes made by the statements issued
permanent.
ROLLBACK Undoes all changes since the beginning of transaction or
since a save point.
 Data Types in SQL:
 The following are the most common data types of SQL:
SL
No
DATA TYPE DESCRIPTION
1 NUMBER
A variable-length column. Allowed values are zero,
positive and negative numbers
2 CHAR A variable length field up to 255 character in length
3 VARCHAR/VARCHAR2 A variable length field up to 2000 character in length
4 DATE/TIME
A fixed length field. The time is stored as a part of the
date. The default format is DD/MON/YY
5 LONG A variable length filed up to 2 GB in length
6 RAW
A variable length filed used for binary data up to 2000
in length
7 LONG RAW
A variable length filed used for binary data up to 2GB
in length
1. NUMBER:
o Used to store a numeric value in a field column.
o It may be decimal, integer or real value.
o General syntax: NUMBER(n, d)

o Where n specifies the number of digits and d specifies the number of digits to right of the
decimal point.
o Example: marks NUMBER(3), average NUMBER(2, 3)
2. CHAR:
o Used to store a character type data in a column.
o General syntax: CHAR(size)
o Where size represents the maximum (255 Characters) number of characters in a column.
o Example: name CHAR(15)
3. VARCHAR/VARCHAR2:
o It is used to store variable length alphanumeric data.
o General syntax: VARCHAR(size) / VARCHAR2(size)
o Where size represents the maximum (2000 Characters) number of characters in a column.
o Example: address VARCHAR2(50)
4. DATE:
o It is used to store date in columns.
o SQL supports the various date formats other than the standard DD-MON-YY.
o Example: dob DATE
5. TIME:
o It is used to store time in columns.
o SQL supports the various time formats other than the standard hh-mm-ss.
o Every DATE and TIME can be added, subtracted or compared as it can be done with other
data types.
6. LONG:
1. It is used to store variable length strings of up to 2GB size.
2. Example: description LONG
 Structure of SQL command:
 Any SQL command is a combination of keywords, identifiers and clauses.
 Every SQL command begins with a keyword (CREATE, SELECT, DELETE and so on) which as
a specific meaning to the language.

 SELECT, FROM and WHERE are keywords.
 The clauses are “FROM student” and “WHERE RegNo=109”.
 Here SELECT and FROM are mandatory, but WHERE is optional.
 Name, Student, RegNo, are identifier that refers to objects in the database.
 Name and RegNo are column names, while Student is a table name.
 The equal sign is an operator and 109 is a numeric constant.
 What is an Operator in SQL?
 An operator is a reserved word or a character used primarily in an SQL statement's WHERE
clause to perform operation(s), such as comparisons and arithmetic operations.
 Operators are used to specify conditions in an SQL statement and to serve as conjunctions for
multiple conditions in a statement.
o Arithmetic operators (+, -, *, / %)
o Comparison operators (>, <, >=, <=, =, !=, <>, !<, !>)
o Logical operators (AND, OR, NOT, IN, BETWEEN, EXISTS, ALL, ANY, LIKE, UNIQUE)
 SQL Logical Operators:
 Here is a list of all the logical operators available in SQL.
Operator Description
ALL The ALL operator is used to compare a value to all values in another value set.
AND
The AND operator allows the existence of multiple conditions in an SQL statement's
WHERE clause.
ANY
The ANY operator is used to compare a value to any applicable value in the list according
to the condition.
BETWEEN
The BETWEEN operator is used to search for values that are within a set of values, given
the minimum value and the maximum value.
EXISTS
The EXISTS operator is used to search for the presence of a row in a specified table that
meets certain criteria.
IN
The IN operator is used to compare a value to a list of literal values that have been
specified.
LIKE The LIKE operator is used to compare a value to similar values using wildcard operators.
NOT
The NOT operator reverses the meaning of the logical operator with which it is used. Eg:
NOT EXISTS, NOT BETWEEN, NOT IN, etc. This is a negate operator.
OR
The OR operator is used to combine multiple conditions in an SQL statement's WHERE
clause.

IS NULL The NULL operator is used to compare a value with a NULL value.
UNIQUE
The UNIQUE operator searches every row of a specified table for uniqueness (no
duplicates).
 Implementation of SQL Commands
 CREATE TABLE
 The SQL CREATE TABLE statement is used to create a new table.
 Creating a basic table involves naming the table and defining its columns and each column's data
type.
 Syntax: Basic syntax of CREATE TABLE statement is as follows:
CREATE TABLE Table_name
(
column1 datatype,
column2 datatype,
column3 datatype,
.....
columnN datatype,
PRIMARY KEY( one or more columns )
);
o Here CREATE TABLE is the keyword followed by the Table_name, followed by an open
parenthesis, followed by the column names and data types for that column, and followed by a
closed parenthesis.
o For each column, a name and a data type must be specified and the column name must be a
unique within the table definition.
o Column definitions are separated by commas (,).
o Uppercase and lowercase letters makes no difference in column names.
o Each table must have at least one column.
o SQL commands should end with a semicolon (;).
 Example: Create a table “STUDENT” that contains five columns: RegNo, Name, Combination,
DOB and Fees.
CREATE TABLE STUDENT
(
RegNo NUMBER (6),
Name VARCHAR2 (15),
Combination CHAR (4),
DOB DATE,
Fees NUMBER (9, 2),
PRIMARY KEY ( RegNo )
);

 It creates an empty STUDENT table which looks like this:
RegNo Name Combination DOB Fees
 Viewing the table information:
o The DESCRIBE or DESC command displays name of the columns, their data type and size
along with the constraints.
 ALTER Statement:
 The table can be modified or changed by using the ALTER command.
 Syntax: Basic syntax of ALTER TABLE statement is as follows:
1. ALTER TABLE Table_name
ADD (column_name1 DataType, Cloumn_name2 DataType……);
MODIFY (column_name1 DataType, Cloumn_name2 DataType……);
DROP (column_name1 DataType, Cloumn_name2 DataType……);
 Example:
 Using the ALTER TABLE command the following tasks cannot be performed
o Changing a table name.
o Changing the column name.
o Decreasing the size of a column if table data exists.
o Changing a column‟s data type.
 DROP TABLE:
 The SQL DROP TABLE statement is used to remove a table definition and all data, indexes,
triggers, constraints, and permission specifications for that table.
 Syntax: Basic syntax of DROP TABLE statement is as follows:

DROP TABLE Table_name;
 Example:
 INSERT:
 The SQL INSERT INTO Statement is used to add new rows of data to a table in the database.
 Syntax:
 There are two basic syntaxes of INSERT INTO statement as follows:
INSERT INTO TABLE_NAME [(column1, column2, column3,...columnN)]
VALUES (value1, value2, value3,...valueN);
 Here, column1, column2,...columnN are the names of the columns in the table into which you
want to insert data.
 You may not need to specify the column(s) name in the SQL query if you are adding values for all
the columns of the table. But make sure the order of the values is in the same order as the columns
in the table.
 METHOD 1: The SQL INSERT INTO syntax would be as follows:
INSERT INTO TABLE_NAME VALUES (value1,value2,value3,...valueN);
 Example: Following statements would create six records in STUDENT table:
SQL> INSERT INTO STUDENT VALUES(1401,'RAMESH','PCMC','07-AUG-99',14000);
1 row created.
SQL> INSERT INTO STUDENT VALUES(1402,'JOHN','PCMB','15-SEP-99',13500);
1 row created.
SQL> INSERT INTO STUDENT VALUES(1403,'GANESH','PCME','19-AUG-99',16000);
1 row created.
SQL> INSERT INTO STUDENT VALUES(1404,'MAHESH','PCMC','14-JAN-98',17650);
1 row created.
SQL> INSERT INTO STUDENT VALUES(1405,'SURESH','PCMB','03-MAR-98',11500);
1 row created.
SQL> INSERT INTO STUDENT VALUES(1410,'ARUN','PCMC','01-APR-04',13000);
 METHOD 2: The SQL INSERT INTO syntax would be as follows:
SQL> INSERT INTO STUDENT (REGNO, NAME, FEES) VALUES (1411, 'SHREYA',24000);
1 row created.

SQL> INSERT INTO STUDENT (REGNO, COMBINATION,FEES) VALUES(1412,
'PCMB',21000);
1 row created.
 All the above statements would produce the following records in STUDENT table:
 UPDATE:
 SQL provides the ability to change data through UPDATE command.
 The UPDATE command used to modify or update an already existing row or rows of a table.
 The basic syntax of UPDATE command is given below.
UPDATE Table_name
SET column_name = value
[, column_name =value ……….]
[WHERE condition];
Example:
SQL> UPDATE STUDENT SET COMBINATION='CEBA' WHERE REGNO=1411;
1 row updated.
SQL> UPDATE STUDENT SET NAME='AKASH' WHERE REGNO=1412;
1 row updated.
 DELETE command:
 In SQL, an already existing row or rows are removed from tables through the use of DELETE
command.
 The basic syntax of DELETE command is given below.
DELETE Table_name
[WHERE condition];
Example:
SQL> DELETE STUDENT WHERE REGNO=1412;
1 row deleted.

 SELECT:
 SQL SELECT statement is used to fetch the data from a database table which returns data in the
form of result table. These result tables are called result-sets.
 Syntax: The basic syntax of SELECT statement is as follows:
SELECT column1, column2, columnN
FROM Table_name;
Compulsory
Part
[WHERE condition(s)]
[GROUPBY column-list]
[HAVING condition(s)]
[ORDER BY column-name(s)];
Optional
Part
 Here, column1, column2...are the fields of a table whose values you want to fetch. If you want to
fetch all the fields available in the field, then you can use the following syntax:
SELECT * FROM table_name;
 Example: Consider the STUDENT table having the following records:
 Following is an example, which would fetch REGNO, NAME and COMBINATION fields of the
customers available in STUDENT table:
 DISTINCT:
 The SQL DISTINCT keyword is used in conjunction with SELECT statement to eliminate all the
duplicate records and fetching only unique records.

 There may be a situation when you have multiple duplicate records in a table. While fetching such
records, it makes more sense to fetch only unique records instead of fetching duplicate records.
 Syntax: The basic syntax of DISTINCT keyword to eliminate duplicate records is as follows:
SELECT DISTINCT column1, column2,.....columnN
FROM Table_name
WHERE [condition]
 First, let us see how the following SELECT query returns duplicate combination records:
 Now, let us use DISTINCT keyword with the above SELECT query and see the result:
SQL> SELECT DISTINCT COMBINATION FROM STUDENT
ORDER BY COMBINATION;
 This would produce the following result where we do not have any duplicate entry:
 WHERE clause – (Extracting specific rows)
 The SQL WHERE clause is used to specify a condition while fetching the data from single table
or joining with multiple tables.
 If the given condition is satisfied then only it returns specific value from the table. You would use
WHERE clause to filter the records and fetching only necessary records.

 The WHERE clause is not only used in SELECT statement, but it is also used in UPDATE,
DELETE statement, etc., which we would examine in subsequent chapters.
 Syntax: The basic syntax of SELECT statement with WHERE clause is as follows:
FROM Table_name
WHERE [condition]
 You can specify a condition using comparison or logical operators like >, <, =, LIKE, NOT, etc.
 Following is an example which would fetch REGNO, NAME and FEES fields from the
STUDENT table where FEES is greater than 15000:
 Following is an example, which would fetch REGNO, NAME and COMBINATION fields from
the STUDENT table for a COMBINATION is „PCMC‟.
 Here, it is important to note that all the strings should be given inside single quotes ('') where as
numeric values should be given without any quote as in above example:
 The SQL AND and OR operators are used to combine multiple conditions to narrow data in an
SQL statement. These two operators are called conjunctive operators.
 These operators provide a means to make multiple comparisons with different operators in the
same SQL statement.
 The AND Operator:
 The AND operator allows the existence of multiple conditions in an SQL statement's WHERE
clause.
 Syntax: The basic syntax of AND operator with WHERE clause is as follows:
FROM Table_name
WHERE [condition1] AND [condition2]...AND [conditionN];

 You can combine N number of conditions using AND operator. For an action to be taken by the
SQL statement, whether it be a transaction or query, all conditions separated by the AND must be
TRUE.
 Following is an example, which would fetch REGNO, NAME and DOB fields from the
STUDENT table where fees is less than 1500 AND combination is „PCMC:
 The OR Operator:
 The OR operator is used to combine multiple conditions in an SQL statement's WHERE clause.
 Syntax: The basic syntax of OR operator with WHERE clause is as follows:
FROM Table_name
WHERE [condition1] OR [condition2]...OR [conditionN];
 You can combine N number of conditions using OR operator. For an action to be taken by the
SQL statement, whether it be a transaction or query, only any ONE of the conditions separated by
the OR must be TRUE.
 Following is an example, which would fetch REGNO, NAME and DOB fields from the
STUDENT table where fees is less than 1500 OR combination is „PCMC:

 ORDER BY – (Sorting the data)
 The SQL ORDER BY clause is used to sort the data in ascending or descending order, based on
one or more columns. Some database sorts query results in ascending order by default.
 Syntax: The basic syntax of ORDER BY clause is as follows:
SELECT column-list
FROM Table_name
[WHERE condition]
[ORDER BY column1, column2, .. columnN] [ASC | DESC];
 You can use more than one column in the ORDER BY clause. Make sure whatever column you
are using to sort, that column should be in column-list.
 Following is an example, which would sort the result in ascending order by NAME:
 Following is an example, which would sort the result in descending order by NAME:

 Working out simple calculations.
 Whenever we want to perform simple calculations such as 10 / 5, we can perform using SELECT
statement which causes an output on monitor.
 But SELECT requires table name to operate.
 One can make use of the dummy table provided by SQL called DUAL which is a single row and
single column table.
 It is used when data from table is not required.
 For example, when a calculation is to be performed such as 10*3, 10/2 etc. and to display the
current system date, we could use the following queries.
 SQL Functions:
 The SQL functions serve the purpose of manipulating data items and returning a result.
 There are many built in functions included in SQL and can be classified as Group Functions and
Scalar Functions.
 Group Functions:
o Functions that act on set of values are called group functions.
o A group functions can takes entire column of data as its arguments and produces a single
data item that summarizes the column.
o Following are the SQL group functions.
Function Description
AVG Returns average value of „N‟, ignoring NULL values
COUNT(expr) Returns the number of rows where „expr‟ is not NULL
COUNT(*)
Returns the number of rows in the table including duplicates and those with
NULL values
MIN Returns minimum value of „expr‟
MAX Returns maximum value of „expr‟
SUM Returns sum of values „N‟
 Scalar Functions:
o Functions that act on only one value at a time are called scalar functions.
o We can further classify the functions using the type of data with they are designed to work.

Function Description
Numeric
Functions
Work with numbers.
Examples: ABS, POWER, ROUND, SQRT
String
Functions
Work with character based data.
Examples: LOWER, INITCAP, UPPER, SUBSTR, LENGTH, LTRIM, RTRIM
Date
Functions
Work with Date data types.
Example: ADD_MONTHS, LAST_DAY, MONTHS_BETWEEN, NEXT_DAY
Conversion
Functions
These functions are used to convert one type of data to another.
Example: TO_NUMBER, TO_CHAR, TO_DATE
Consider the EXAMINATION table:
RegNo Name CC Phy Che Mat Cs Total City
101 Ajay C1 98 100 97 99 394 Hassan
102 Banu C2 38 50 37 49 174 Belur
103 Chandan C2 100 100 97 99 396 Mysuru
104 John C3 78 80 67 79 304 Alur
105 Kaleem C1 88 80 91 79 338 Hassan
106 Raheem C2 100 98 97 79 374 Hassan
107 Sanjay C3 47 60 56 78 241 Alur
108 Tarun C3 33 34 77 28 172 Arasikere
109 Uday C2 100 98 97 79 374 Hassan
110 Venki C3 47 60 56 78 241 Belur
 COUNT ( ) Function:
 This function is used to count the number of values in a column.
 COUNT (*) is used to count the number of rows in the table including duplicates and those with
NULL values.
 Example 1:
o SELECT COUNT (*) FROM EXAMINATION;
o The above query returns 10.
 Example 2:
o SELECT COUNT (RegNo) FROM EXAMINATION WHERE CC = „C3‟ ;
o The above query returns 4.

 AVG ( ) Function:
 This function is used to find the average of the values in a numeric column.
 Example 1:
o SELECT AVG (Cs) FROM EXAMINATION;
o The above query returns 74.7
 SUM ( ) Function:
 This function is used to find the sum of the values in a numeric column.
 Example:
o SELECT SUM (Phy) FROM EXAMINATION;
o The above query returns 729
 MAX ( ) Function:
 This function is used to find the maximum values in a column.
 Example:
o SELECT MAX (Phy) FROM EXAMINATION;
 MIN ( ) Function:
 This function is used to find the minimum values in a column.
 Example:
o SELECT MIN (Phy) FROM EXAMINATION;
 GROUP BY (Grouping Result)
 The SQL GROUP BY clause is used in collaboration with the SELECT statement to arrange
identical data into groups.
 The GROUP BY clause follows the WHERE clause in a SELECT statement and precedes the
ORDER BY clause.
 Syntax: The basic syntax of GROUP BY clause is given below.
SELECT column1, column2
FROM Table_name
WHERE [ conditions ]
GROUP BY column1, column2
ORDER BY column1, column2

 Example 1: To find the number of students in each college.
SELECT CC, COUNT (CC)
FROM EXAMINATION
GROUP BY CC;
 Example 2: To find the number of students, sum, average, maximum, minimum marks in
computer science from each city.
SELECT City, COUNT (City), SUM (Cs), AVG (Cs), MAX (Cs), MIN (Cs)
FROM EXAMINATION
GROUP BY City;
 SQL CONSTRAINTS:
 Constraints are the rules enforced on data columns on table.
 These are limiting the type of data that can go into a table.
 This ensures the accuracy and reliability of the data into the database.
 SQL allows two types of constraints.
o Column level constraints: These constraints are defined along with the column definition
when creating or altering a table structure. These constraints apply only to individual
columns.
o Table level constraints: These constraints are defined after all the table columns when
creating or altering a table structure. These constraints apply to groups of one or more
columns.
 Following are the commonly used constraints available in SQL.
Constraints Description
NOT NULL Ensures that a column cannot have NULL value
UNIQUE Ensures that all values in column are different
PRIMARY KEY Uniquely identified eac row in a database table.
FOREIGN KEY Uniquely identified each rown in any other database table
DEFAULT Provides a default value for a column when none is specified
CHECK Ensures that all values in a column satisfy certain condition.
 NOT NULL Constraint:
 By default column can hold NULL values.
 When a column is defined as NOT NULL then the column becomes a mandatory column.
 It implies that a value must be entered into the column if the row is to be inserted for storage in the
table.

 Example: Consider the following CREATE TABLE command creates a new table called
PRODUCT and add six columns, two which PID and Description specify not to accept NULLs.
CREATE TABLE PRODUCT
(
PID CHAR (4) NOT NULL,
Description VARCHAR2 (25), NOT NULL
CompanyId CHAR (10),
DOM DATE,
Type CHAR (10),
Price NUMBER (10,2)
);
 UNIQUE Constraints:
 This constraint ensures that no rows have the same value in the specified column(s). A table must
have many unique keys.
 Example: UNIQUE constraint applied on PID of PRODUCT table ensures that no rows have the
same PID value, as shown below
(
PID CHAR (4) NOT NULL UNIQUE,
DOM DATE,
Type CHAR (10),
Price NUMBER (10,2)
);
 PRIMARY KEY Constraints:
 A primary key is a field which uniquely identifies each row in a database table. A primary key in a
table has special attributes:
 By default this column is NOT NULL. It defines the column as a mandatory column i.e. the
column cannot be left blank.
 The data held in this column must be unique.
 Example:
(
PID CHAR (4) PRIMARY KEY,
DOM DATE,
Type CHAR (10),
Price NUMBER (10,2)
);

 FOREIGN KEY Constraint:
 A FOREIGN KEY is used to link two tables together.
 A foreign key is a column whose values are derived from the PRIMARY KEY of some other table.
 Example:
(
CompanyId CHAR (10) REFERENCES COMPANY (CID)
DOM DATE,
Type CHAR (10),
Price NUMBER (10,2)
);
CREATE TABLE COMPANY
(
CID CHAR (10) PRIMARY KEY,
CProfile VARCHAR2 (200),
Noofproducts NUMBER (20),
DOE DATE
);
 DEFAULT Constraints:
 A default value can be specified for a column using the DEFAULT clause.
 The DEFAULT constraint provides a default value to a column when the INSERT INTO
command does not provide a specific value.
 Example:
(
DOM DATE,
Type CHAR (10),
Price NUMBER (10, 2) DEFALUT 1000.00
);
 CHECK Constraints:
 The CHECK Constraint is used to establish a TRUE/FALSE condition that is applied to the data
placed in a column.
 If a value does not meet the condition, it cannot be placed in the column.
 Example:

(
PID CHAR (4) CHECK (PID LIKE ‘P%’),
Description VARCHAR2 (25),
DOM DATE,
Type CHAR (10),
Price NUMBER (10, 2) CHECK (Price>0)
);
 TABLE Constraints:
 When a constraint is applied to a group of columns of the table, it is called a table constraint.
 Column constraint is defined along with the end of the column.
 Table constraints are defined at the end of the table.
 Example:
(
PID CHAR (4) NOT NULL,
Description VARCHAR2 (25) NOT NULL,
DOM DATE,
Type CHAR (10),
Price NUMBER (10, 2),
PRIMARY KEY (PID, Description)
);
 Joins
 The SQL Joins clause are used to fetch/retrieve data from two or more tables based on the join
condition which is specified in the WHERE condition.
 Basically data tables are related to each other with keys. We can used these keys relationship in
SQL joins.
 SQL Join Types:
 There are different types of joins available in SQL:
o INNER JOIN: returns rows when there is a match in both tables.
o LEFT JOIN: returns all rows from the left table, even if there are no matches in the right
table.
o RIGHT JOIN: returns all rows from the right table, even if there are no matches in the left
table.
o FULL JOIN: returns rows when there is a match in one of the tables.
o SELF JOIN: is used to join a table to itself as if the table were two tables, temporarily
renaming at least one table in the SQL statement.

o CARTESIAN JOIN: returns the Cartesian product of the sets of records from the two or
more joined tables.
 Creating VIEWs:
 Database Views are created using the CREATE VIEW statement.
 Views can be created from a single table, multiple tables or another view.
 To create a view, a user must have the appropriate system privilege according to the specific
implementation.
 Syntax: The basic CREATE VIEW syntax is as follows:
SQL> CREATE VIEW view_name AS
SELECT column1, column2…..
FROM table_name
WHERE [ condition ];
 Privileges and Roles:
 Privileges: Privileges defines the access rights provided to a user on a database object.
 There are two types of privileges:
o System Privileges: This allows the user to CREATE, ALTER, or DROP database objects.
o Object privileges: This allows the user to EXECUTE, SELECT, INSERT, UPDATE or
DELETE data from database objects to which privileges apply.
CHAPTER 14 – STRUCTURED QUERY LANGUAGE BLUE PRINT
VSA (1 marks) SA (2 marks) LA (3 Marks) Essay (5 Marks) Total
- 01 Question - 01 Question 02 Question
- Question no 17 - Question no 36 06 Marks
Important Questions
Two Marks Questions:
1. Give the syntax and example for DELETE command in SQL. [March 2015]
2. List the data types supported in SQL. [June 2015]
3. Write the syntax for DELETE and INSERT commands in SQL. [March 2016]
4. Mention the logical operators used in SQL. [June 2016]
5. Give the syntax and example of UPDATE command in SQL. [March 2017]

6. What is the difference between ORDER BY and GROUP BY clause used in SQL? Give example
for each. [June 2017]
7. List the relational operators supported by SQL.
8. Why the DROP command used? Write its syntax.
9. What are the difference between DROP and DELETE command?
10. Give the syntax and example for CREATE VIEW command in SQL.
11. Classify the built-in functions in SQL.
Five Marks Question:
1. Explain various group functions in SQL. [March 2015, March 2017, June 2017]
2. What is data definition language? Explain SELECT and UPDATE command. [June 2015]
3. Describe any five logical operators available in SQL. [March 2016]
4. What is SQL? Explain the different SQL commands.
5. What is the purpose of CREATE command? Write the syntax and example of CREATE command.
6. Explain SELECT statement with syntax and with minimum 3 examples.
7. Explain 5 variations of SELECT command.
8. What are SQL constraints? Explain any two constraints.
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chapter-14-sql-commands.pdf

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chapter-14-sql-commands.pdf