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प्रश्न
Differentiate between the following statement:
ALTER and UPDATE
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उत्तर
Alter
- ALTER command is Data Definition Language (DDL).
- ALTER command will perform the action on the structure level and not on the data level.
- ALTER Command is used to add, delete, and modify the attributes of the relations (tables) in the database.
Update
- UPDATE Command is a Data Manipulation Language (DML).
- UPDATE command will perform on the data level.
- UPDATE Command is used to update existing records in a database.
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संबंधित प्रश्न
Each table comprises of ______ and ______.
A tuple in RDBMS is referred to as ______ of a table.
Which of the following is not an RDBMS?
Which of the following are included in defining a schema?
To know the names of existing databases, we use the statement:
What statement will you give to view the structure of a table?
How will you add a primary key to a relation?
How will you add two columns coll and col2(composite key) as primary key to a relation?
How will you add a foreign key to a relation?
Which statement is used to remove a table from the database?
Raju's date of birth is 21/06/2006. How will his date be added to database?
A shop called Wonderful Garments which sells school uniforms maintains a database SCHOOLUNIFORM as shown below. It consisted of two relations - UNIFORM and COST. They made UniformCode the primary key for UNIFORM relations. Further, they used UniformCode and Size to be composite keys for COSTrelation. By analyzing the database schema and database state, specify SQL queries to rectify the following anomalies.
- M/S Wonderful Garments also keeps handkerchiefs of red colour, medium size of Rs. 100 each.
- INSERT INTO COST (UCode, Size, Price) values (7, 'M', 100);
When the above query is used to insert data, the values for the handkerchief without entering its details in the UNIFORM relation are entered. Make a provision so that the data can be entered in the COST table only if it is already there in the UNIFORM table. - Further, they should be able to assign a new UCode to an item only if it has a valid UName. Write a query to add appropriate constraints to the SCHOOLUNIFORM database.
- Add the constraint so that the price of an item is always greater than zero.
Using the CARSHOWROOM database given in the chapter, write the SQL queries for the following:
- Add a new column Discount in the INVENTORY table.
- Set appropriate discount values for all cars keeping in mind the following:
(i) No discount is available on the LXI model.
(ii) VXI model gives a 10 percent discount.
(iii) A 12 percent discount is given on cars other than the LXI model and VXI model. - Display the name of the costliest car with the fuel type “Petrol”.
- Calculate the average discount and total discount available on Baleno cars.
- List the total number of cars having no discount.
______ command is used to remove the primary key from a table in SQL.
Which of the following commands will delete the table from the MYSQL database?
To establish a connection between Python and SQL databases, connect() is used. Which of the following arguments may not necessarily be given while calling connect()?
Write the command to view all databases.
Name any two DDL commands.
Ms Shalini has just created a table named “Employee” containing columns Ename, Department and Salary. After creating the table, she realized that she has forgotten to add a primary key column in the table. Help her in writing an SQL command to add a primary key column EmpId of integer type to the table Employee.
Thereafter, write the command to insert the following record in the table:
EmpId- 999
Ename- Shweta
Department: Production
Salary: 26900Consider the table Personal given below:
| Table: Personal | ||||
| P_ID | Name | Desig | Salary | Allowance |
| P01 | Rohit | Manager | 89000 | 4800 |
| P02 | Kashish | Clerk | NULL | 1600 |
| P03 | Mahesh | Superviser | 48000 | NULL |
| P04 | Salil | Clerk | 31000 | 1900 |
| P05 | Ravina | Superviser | NULL | 2100 |
Based on the given table, write SQL queries for the following:
- Increase the salary by 5% of personals whose allowance is known.
- Display Name and Total Salary (sum of Salary and Allowance) of all personals. The column heading ‘Total Salary’ should also be displayed.
- Delete the record of Supervisors who have salary greater than 25000.
