JOINS and SET Operations

Both A and R are true and R is the correct explanation of A.

Explanation
The Cartesian product and joins are related because a Cartesian product is a join without any condition. While a join is a query that combines rows from two or more tables based on a specified condition, a Cartesian product (or cross join) pairs every row from one table with every row from another, resulting in a set that includes all possible combinations of rows.

Both A and R are true and R is the correct explanation of A.

Explanation
The cardinality of a Cartesian product can be predetermined because it is the product of the cardinalities of the two participating tables, i.e., n1 * n2 where n1 and n2 are cardinalities of the two participating tables. This is unlike joins, where the cardinality depends on the specific conditions used to match the rows from the involved tables.

A is false but R is true.

Explanation
The cartesian product does not require any identical columns, it pairs each row from one table with every row from another table, creating all possible combinations of rows and returning them.

A is true but R is false.

Explanation
In an equi-join, the values in the columns being joined are compared for equality. The join condition can use various types of comparisons, including equality (=) and other logical operators such as "<>", "<", ">", "<=", ">=".

Both A and R are true but R is not the correct explanation of A.

Explanation
The join in which columns are compared for equality is called an Equi-join. A non-equi-join involves comparing columns with non-equality conditional operators, such as '<>', '<', '>', '<=', and '>=', to specify relationships other than equality between the columns.

Both A and R are true and R is the correct explanation of A.

Explanation
In certain types of joins, such as LEFT JOIN and RIGHT JOIN, all records from one table appear in the result set regardless of whether they have matching rows in the other table. In a LEFT JOIN, all rows from the left table are included along with matching rows from the right table and NULL values for non-matching rows in the right table. Similarly, in a RIGHT JOIN, all rows from the right table are included along with matching rows from the left table and NULL values for non-matching rows in the left table.

Both A and R are true and R is the correct explanation of A.

Explanation
The UNION clause combines the rows of the participating tables, removing duplicate rows from the final output. On the other hand, UNION ALL retains all duplicate rows from the tables in the final output.

A is false but R is true.

Explanation
The MINUS operator returns the rows that are only in the first result set but not in the second, while the INTERSECT operator returns all rows that are in both result sets. Hence, the MINUS and INTERSECT operators are different.

The unrestricted join of two tables is a relation that contains all possible concatenations of all rows of both the participating relations (tables).

A join is a query that combines rows from two or more tables based on a condition.

In an equi-join, the values in the columns being joined are compared for equality using the "=" operator, and all columns from the joined tables are included in the result set, even if they are identical. On the other hand, a non-equi-join specifies a relationship other than equality between the columns using operators like <, >, <=, >=, !=, or <>.

In SQL, set operations include UNION, INTERSECTION, and MINUS to combine the rows from two or more tables.

In SQL, UNION ALL retains all duplicate rows from tables in the final output, while UNION removes duplicate rows from the final output.

In SQL, the INTERSECT operator returns rows common to two tables, while the MINUS (EXCEPT) operator retrieves unique rows from the first table that are not in the second table.

Join

Reason — A join is a query that combines rows from two or more tables or views. In a join-query, more than one table are listed in FROM clause.

Join condition

Reason — A condition specified in a JOIN query that determines how the rows from two tables are combined is referred to as a "join condition."

Empty join

Reason — The join types in SQL are natural join, equi-join, right join, inner join, left join, and non-equi-join.

Cartesian

Reason — When a join query has no join condition specified, it results in a Cartesian product. This means that every row from the first table is combined with every row from the second table.

Unrestricted Join

Reason — A Cartesian product is called an unrestricted join because all possible combinations of rows from multiple tables are created without any conditions.

Equi-join

Reason — An equi-join compares columns from two or more tables for equality using the "=" operator in the join condition.

Equi-join

Reason — In an equi-join, all columns from the joining tables appear in the output, even if they are identical. This can result in duplicate columns in the output table.

Natural

Reason — In a natural join, no duplicate columns appear in the output table. This is because a natural join is a type of join in which only one of the identical columns (coming from the joined tables) is included in the output.

Natural

Reason — The USING subclause in a SELECT statement produces a natural join, where columns with the same name in the joined tables are automatically used as join conditions, resulting in a natural join operation.

Equi-join

Reason — The ON subclause in a SELECT statement produces an equi-join, where columns from the joined tables are compared for equality using the specified conditions in the ON clause.

It combines the unique rows of two different queries which have the same set of attributes in the select clause

Reason — The UNION operation in SQL combines the results of two queries into a single result set, including only distinct rows from both queries. The queries must have the same number of columns having similar data types and order.

It returns the common rows of two different queries which have the same set of attributes in the select clause

Reason — The INTERSECT operation in SQL returns common rows from different queries. These queries must have the same number of columns with the same data types in corresponding positions in the SELECT clause.

It includes the rows of the first query but excludes the results of the second query

Reason — The EXCEPT (or MINUS) operator in SQL is used to retrieve unique rows from the first query, specifically those rows that exist in the first query but not in the second query.

EXCEPT

Reason — The other name for the MINUS operator in SQL is EXCEPT.

SELECT employee_id, d.department_id, department_name, salary
FROM EMPL e 
JOIN DEPT d 
ON e.department_id = d.department_id;

Reason — Both SQL statements are equivalent as they perform an inner join between the EMPL and DEPT tables based on their department_id columns. The first SQL statement uses implicit join syntax with a WHERE clause to specify the join condition, while the second SQL statement uses explicit join syntax with the JOIN keyword and ON clause.

False

Reason — A non-equi-join is a query that specifies a relationship other than equality between columns, often using comparison operators like >, <, >=, <=, etc. On the other hand, a join in which only one of the identical columns from joined tables exists is called a natural join.

False

Reason — Natural join is a join in which only one of the identical columns from joined tables exists.

True

Reason — In an equi-join, all columns from the joining tables are included in the output, even if they are identical, which can lead to duplicate columns in the output.

True

Reason — An inner join in SQL combines only the rows from two tables that have matching values in the specified columns, based on the join condition. Rows that do not have matching values in both tables are excluded from the result set.

False

Reason — A join condition can use various types of comparisons, including equality (=) and other logical operators such as "<>", "<", ">", "<=", ">=".

True

Reason — A left join includes all rows from the left table, regardless of whether there are matches in the right table. For unmatched rows from the left table, NULL values are shown in the columns of the right table.

True

Reason — The outer join returns all the rows from both tables being joined, including any rows that do not have a match in the other table.

True

Reason — MINUS operator is also called EXCEPT operator as both are used to return rows that are in the first table and not in the second table.

True

Reason — The UNION operator returns all unique rows from the SELECT queries.

False

Reason — UNION ALL will retain all the duplicate rows from tables in the final output, while UNION will remove the duplicate rows and include only distinct rows in the final output.

The Cartesian product of two tables is a relation that contains all possible concatenations of all rows of both the participating relations (tables).

The Cartesian product and joins are related because a Cartesian product, also known as a cross join, is a very basic type of join without any condition. It pairs every row from one table with every row from another, creating a complete combination of all rows. Meanwhile, a join is a query that combines rows from two or more tables based on a specified condition.

A join is a query that combines rows from two or more tables based on a condition.

The join in which only one of the identical columns from the joined tables exists is called a natural join, while the join in which columns are compared for equality is called an equi-join.

A table alias is a temporary label given along with table name in the FROM clause.

Table aliases are used to give a temporary name to a table within a SQL query, making it easier to read and reference columns, especially when working with long table names, self-joins, or multiple references to the same table.

The join, in which columns are compared for equality, is called equi-join. The comparison operator used is "=".

A non-equi-join is a query that specifies some relationship other than equality between the columns. The comparison operators used are '<>', '<', '>', '<=', and '>='.

A join is a query that combines rows from two or more tables based on a condition.

In MySQL, we can create two main types of joins: unrestricted joins, which include the Cross Join or Cartesian Product, and restricted joins, which include Equi Join, Non-Equi Join, Natural Join, Left Join, and Right Join.

The two ways to create cartesian product of two tables in MySQL are as follows:

1. Creating Cartesian Product Without Join Condition:

SELECT * 
FROM table1 JOIN table2;

2. Creating Cartesian Product Using CROSS JOIN Clause:

SELECT * 
FROM table1
CROSS JOIN table2;

In a LEFT JOIN, all rows from the left table are included along with matching rows from the right table, and NULL values are used for non-matching rows in the right table. Conversely, a natural join is a join where only one of the identical columns from the joined tables exists.

A cross join is a very basic type of join that simply pairs every row from one table with every row from another table. On the other hand, a natural join is a join where only one of the identical columns from the joined tables exists.

Yes, we can join two tables without using the JOIN keyword. This can be done using the comma (,) operator in the FROM clause to combine tables and using the WHERE clause to specify the join condition. The syntax to perform a JOIN between tableA and tableB on the common column "column1" is as follows:

SELECT * FROM tableA, tableB WHERE tableA.column1 = tableB.column1;

The difference between ON and USING sub-clauses of JOIN clause of SELECT is that ON clause requires a complete join-condition whereas USING clause requires just the name of a join field. USING subclause produces natural join whereas ON clause produces equi-join.

To obtain the Cartesian product of two tables, we multiply the number of rows in the first table by the number of rows in the second table, and the resulting table will have the sum of columns from both tables.

The Cartesian product of "STUDENT" and "TEACHER" will have 4 * 3 = 12 rows and 2 + 4 = 6 columns.

Therefore, the resulting Cartesian product will have 12 rows and 6 columns.

The SQL UNION operator is used to combine the results of two or more queries into a single result set. It removes duplicate rows from the final output.

No, UNION and UNION ALL are not same. UNION ALL will retain all the duplicate rows from tables in the final output while UNION will remove the duplicate rows from the final output.

In SQL, INTERSECT operation returns all rows that are in both result sets.

The MINUS operator returns the rows that are only in the first result set but not in the second result set.

1.

SELECT EMPLOYEE.EMPLOYEEID, EMPLOYEE.NAME, EMPLOYEE.JOBID, JOB.JOBTITLE
FROM EMPLOYEE, JOB
WHERE EMPLOYEE.JOBID = JOB.JOBID;

+------------+-------------------+-------+--------------------------+
| EMPLOYEEID | NAME              | JOBID | JOBTITLE                 |
+------------+-------------------+-------+--------------------------+
| E1         | SUMIT SINHA       |   102 | VICE PRESIDENT           |
| E2         | VIJAY SINGH TOMAR |   101 | PRESIDENT                |
| E3         | AJAY RAJPAL       |   103 | ADMINISTARTION ASSISTANT |
| E4         | MOHIT RAMNANI     |   102 | VICE PRESIDENT           |
| E5         | SHAILJA SINGH     |   103 | ADMINISTARTION ASSISTANT |
+------------+-------------------+-------+--------------------------+

2.

SELECT EMPLOYEE.NAME, EMPLOYEE.SALES, JOB.JOBTITLE
FROM EMPLOYEE, JOB 
WHERE EMPLOYEE.JOBID = JOB.JOBID
AND EMPLOYEE.SALES > 1300000;

+---------------+---------+--------------------------+
| NAME          | SALES   | JOBTITLE                 |
+---------------+---------+--------------------------+
| AJAY RAJPAL   | 1400000 | ADMINISTARTION ASSISTANT |
| SHAILJA SINGH | 1450000 | ADMINISTARTION ASSISTANT |
+---------------+---------+--------------------------+

3.

SELECT EMPLOYEE.NAME, JOB.JOBTITLE
FROM EMPLOYEE, JOB 
WHERE EMPLOYEE.JOBID = JOB.JOBID
AND EMPLOYEE.NAME LIKE '%SINGH%';

+-------------------+--------------------------+
| NAME              | JOBTITLE                 |
+-------------------+--------------------------+
| VIJAY SINGH TOMAR | PRESIDENT                |
| SHAILJA SINGH     | ADMINISTARTION ASSISTANT |
+-------------------+--------------------------+

4. In the given tables, EMPLOYEE and JOB, the JOBID column in the EMPLOYEE table is a foreign key referencing the JOBID column in the JOB table.

5.

UPDATE EMPLOYEE
SET JOBID = 104
WHERE EMPLOYEEID = 'E4';

SELECT * FROM EMPLOYEE ;

+------------+-------------------+---------+-------+
| EMPLOYEEID | NAME              | SALES   | JOBID |
+------------+-------------------+---------+-------+
| E1         | SUMIT AINHA       | 1100000 |   102 |
| E2         | VIJAY SINGH TOMAR | 1300000 |   101 |
| E3         | AJAY RAJPAL       | 1400000 |   103 |
| E4         | MOHIT RAMNANI     | 1250000 |   104 |
| E5         | SHAILJA SINGH     | 1450000 |   103 |
+------------+-------------------+---------+-------+

SELECT job, AVG(Sal) AS AvgSalary 
FROM Empl 
GROUP BY job HAVING COUNT(*) > 3;

+----------+-----------+
| job      | AvgSalary |
+----------+-----------+
| CLERK    |    1037.5 |
| SALESMAN |      1400 |
+----------+-----------+

SELECT Job 
FROM Empl 
GROUP BY Job HAVING MAX(Sal) >= 3000;

+-----------+
| Job       |
+-----------+
| PRESIDENT |
| ANALYST   |
+-----------+

A join is a query that combines rows from two or more tables based on a condition.

In MySQL, we can create two main types of joins: unrestricted joins, which include the Cross Join or Cartesian Product, and restricted joins, which include Equi Join, Non-Equi Join, Natural Join, Left Join, and Right Join.

(i)

SELECT COUNT(ADDRESS) FROM STUDENTS;

+----------------+
| COUNT(ADDRESS) |
+----------------+
|              4 |
+----------------+

(ii)

SELECT S.NAME, S.CLASS, SP.GRADE 
FROM STUDENTS S, SPORTS SP 
WHERE S.ADMNO = SP.ADMNO;

+-------+-------+-------+
| NAME  | CLASS | GRADE |
+-------+-------+-------+
| MEENA |    12 | A     |
| VANI  |    10 | B     |
| MEENA |    12 | B     |
| SURAJ |    11 | A     |
+-------+-------+-------+

(iii)

SELECT S.NAME, SP.COACHNAME 
FROM STUDENTS S, SPORTS SP 
WHERE S.ADMNO = SP.ADMNO;

+-------+--------------+
| NAME  | COACHNAME    |
+-------+--------------+
| MEENA | MR.GOVARDHAN |
| VANI  | MR.TEWANI    |
| MEENA | MS.CHADHA    |
| SURAJ | MR.RAVI      |
+-------+--------------+

(i)

SELECT E.ENO, E.ENAME, E.SALARY, D.DNAME
FROM EMPLOYEE E, DEPARTMENT D
WHERE E.DEPT = D.DEPT AND (E.AGE BETWEEN 25 AND 35);

+-----+--------+--------+-----------+
| ENO | ENAME  | SALARY | DNAME     |
+-----+--------+--------+-----------+
|   3 | NALINI |  60000 | COMPUTERS |
|   5 | SURYA  |  58000 | ENGLISH   |
+-----+--------+--------+-----------+

(ii)

SELECT D.DNAME, E.ENAME
FROM EMPLOYEE E, DEPARTMENT D
WHERE E.ENO = D.HOD;

+-----------+---------+
| DNAME     | ENAME   |
+-----------+---------+
| COMPUTERS | MONA    |
| ECONOMICS | MUKHTAR |
| ENGLISH   | SURYA   |
+-----------+---------+

(iii)

SELECT ENAME, SALARY, ZONE, (SALARY * 30/100) AS INCOME_TAX
FROM EMPLOYEE;

+---------+--------+-------+------------+
| ENAME   | SALARY | ZONE  | INCOME_TAX |
+---------+--------+-------+------------+
| MONA    |  70000 | EAST  | 21000.0000 |
| MUKHTAR |  71000 | WEST  | 21300.0000 |
| NALINI  |  60000 | EAST  | 18000.0000 |
| SANAJ   |  65000 | SOUTH | 19500.0000 |
| SURYA   |  58000 | NORTH | 17400.0000 |
+---------+--------+-------+------------+

The two ways to create cartesian product of two tables in MySQL are as follows:

1. Creating Cartesian Product Without Join Condition:

SELECT * 
FROM table1 JOIN table2;

2. Creating Cartesian Product Using CROSS JOIN Clause:

SELECT * 
FROM table1
CROSS JOIN table2;

In a LEFT JOIN, all rows from the left table are included along with matching rows from the right table, and NULL values are used for non-matching rows in the right table. Conversely, a natural join is a join where only one of the identical columns from the joined tables exists.

1. LEFT JOIN Example:

SELECT name, lastname
FROM empl LEFT JOIN dept ON empl.id = dept.id;

The result of this query would return name and lastname values from the empl table and all available values from the dept table. NULL is returned for non-existing values in dept table.

2. NATURAL JOIN Example:

SELECT * FROM empl NATURAL JOIN dept;

The query returns all columns from empl and dept tables, with rows having matching values in their common columns.

A cross join is a very basic type of join that simply pairs every row from one table with every row from another table. On the other hand, a natural join is a join where only one of the identical columns from the joined tables exists.

1. CROSS JOIN Example:

SELECT *
FROM students
CROSS JOIN subjects;

This CROSS JOIN will pair every row from the students table with every row from the subjects table, resulting in a Cartesian product of the two tables.

2. NATURAL JOIN Example:

SELECT *
FROM students
NATURAL JOIN subjects;

This NATURAL JOIN will automatically match the common columns and return rows where the values match.

The "TRAINS" table in the database has a degree of 3, indicating it contains three attributes or columns and it has a cardinality of 8, indicating it consists of eight rows or tuples. Therefore, the "TRAINS" table has 8 rows and 3 columns.

(i)

SELECT * 
FROM PRODUCT 
WHERE PRICE BETWEEN 40 AND 120;

+------+-------------+--------------+-------+
| P_ID | ProductName | Manufacturer | Price |
+------+-------------+--------------+-------+
| P001 | MOISTURISER | XYZ          |    40 |
| P004 | SHAMPOO     | TAP          |    95 |
+------+-------------+--------------+-------+

(ii)

SELECT C.CLIENTNAME, C.CITY, P.PRODUCTNAME, P.PRICE 
FROM CLIENT C, PRODUCT P 
WHERE C.P_ID = P.P_ID;

+---------------+-----------+---------------+-------+
| CLIENTNAME    | CITY      | PRODUCTNAME   | PRICE |
+---------------+-----------+---------------+-------+
| DREAMZ DISNEY | NEW DELHI | SANITIZER     |    35 |
| LIFE LINE INC | MUMBAI    | LENS SOLUTION |   350 |
| 98.4          | NEW DELHI | MOISTURISER   |    40 |
| APPOLO        | BANGALORE | BATH SOAP     |    25 |
+---------------+-----------+---------------+-------+

(iii)

UPDATE PRODUCT 
SET PRICE = PRICE + 20;

(i) The foreign key in the "Member" table is the "Divno" column, which references the "Divno" column in the "Division" table.

(ii)

SELECT m.Name, d.Divname 
FROM Member m JOIN Division d ON m.Divno = d.Divno;

+----------+---------+
| Name     | Divname |
+----------+---------+
| SHANKHYA | Media   |
| SUNISH   | Dance   |
+----------+---------+

SELECT DIVNO FROM MEMBER 
UNION ALL
SELECT DIVNO FROM DIVISION;

+-------+
| DIVNO |
+-------+
|    10 |
|    20 |
|    50 |
|    10 |
|    20 |
|    30 |
+-------+

SELECT DISTINCT DIVNO FROM MEMBER 
UNION 
SELECT DISTINCT DIVNO FROM DIVISION;

+-------+
| DIVNO |
+-------+
|    10 |
|    20 |
|    50 |
|    30 |
+-------+

SELECT m.Divno 
FROM Member m 
LEFT JOIN Division d ON m.Divno = d.Divno 
WHERE d.Divno IS NULL;

+-------+
| Divno |
+-------+
|    50 |
+-------+

SELECT D.Divno
FROM Division D
LEFT JOIN Member M ON D.Divno = M.Divno
WHERE M.Divno IS NULL;

+-------+
| Divno |
+-------+
|    30 |
+-------+

SELECT Divno 
FROM Division NATURAL JOIN Member;

+-------+
| Divno |
+-------+
|    10 |
|    20 |
+-------+

(i) No, the column 'PHONE' cannot be set as the primary key of the table "DRIVER" because it contains NULL values and primary keys must have unique, non-NULL values for each row.

Or

The primary key in the 'DRIVER' table is 'DRIVERID' because it uniquely identifies each driver, and it does not allow null values, ensuring that each row can be uniquely identified.

(ii) The data type used for the "PHONE" column is "CHAR", which is a fixed-length data type. "CHAR" pads the values with spaces to ensure each value takes up the same amount of storage space.

Or

The data type and size for the column "DRIVERID" would be "VARCHAR(4)" to accommodate the alphanumeric values of length 4.

(i)

SELECT T.ORDERID, T.ITEM, D.DRIVERID, D.DRIVERNAME 
FROM TRANSPORTER T, DRIVER D 
WHERE T.DRIVERID = D.DRIVERID AND D.DRIVERGRADE = 'A';

+---------+--------------+----------+--------------+
| ORDERID | ITEM         | DRIVERID | DRIVERNAME   |
+---------+--------------+----------+--------------+
|    1121 | REFRIGERATOR | D101     | RADHEY SHYAM |
|    1122 | TELEVISION   | D101     | RADHEY SHYAM |
+---------+--------------+----------+--------------+

(ii)

SELECT D.DRIVERID, D.DRIVERNAME, T.TRANSPORTDATE 
FROM TRANSPORTER T, DRIVER D 
WHERE T.DRIVERID = D.DRIVERID AND T.TRANSPORTDATE > '2019-03-01';

+----------+--------------+---------------+
| DRIVERID | DRIVERNAME   | TRANSPORTDATE |
+----------+--------------+---------------+
| D103     | TIMSY YADAV  | 2019-03-19    |
| D101     | RADHEY SHYAM | 2019-04-12    |
| D101     | RADHEY SHYAM | 2019-05-06    |
| D103     | TIMSY YADAV  | 2019-05-07    |
| D102     | JAGAT SINGH  | 2019-06-15    |
+----------+--------------+---------------+

Or

The number of rows in the Cartesian product of the two tables "TRANSPORTER" and "DRIVER" would be the product of the number of rows in each table. In this case, since the "TRANSPORTER" table has 5 rows and the "DRIVER" table has 4 rows, the Cartesian product would have 5 * 4 = 20 rows.

(iii)

SELECT T.ORDERED, D.DRIVERID, D.DRIVERNAME 
FROM TRANSPORTER T, DRIVER D 
WHERE T.DRIVERID = D.DRIVERID AND T.ITEM = 'TELEVISION';

+---------+----------+--------------+
| ORDERED | DRIVERID | DRIVERNAME   |
+---------+----------+--------------+
|    1120 | D103     | TIMSY YADAV  |
|    1122 | D101     | RADHEY SHYAM |
+---------+----------+--------------+