Data Manipulation Language (DML) Quiz
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Data Manipulation Language (DML) Quiz

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Questions and Answers

What is the result of executing a DELETE query without a WHERE clause on the CUSTOMERS table?

  • No records are affected and the table remains unchanged.
  • Only records matching certain conditions are deleted.
  • Only the specified record is deleted.
  • All records in the CUSTOMERS table are deleted. (correct)
  • What would happen if an UPDATE query is executed without a WHERE clause?

  • No records are updated.
  • Only records that are NULL are updated.
  • Only the first record is updated.
  • All records in the specified columns are updated. (correct)
  • Which operators can be used to specify conditions in a WHERE clause?

  • Comparison and logical operators such as >, <, AND, OR (correct)
  • Only arithmetic operators like + or -
  • Any form of text or numeric manipulation operators
  • Only logical operators like AND or OR
  • How do you write an UPDATE query to change the ADDRESS for a specific customer in the CUSTOMERS table?

    <p>UPDATE CUSTOMERS SET ADDRESS = 'New Address' WHERE ID = 6;</p> Signup and view all the answers

    What role does the WHERE clause serve when using a SELECT statement?

    <p>It filters records based on specified conditions.</p> Signup and view all the answers

    What does the acronym CRUD represent in the context of a relational database?

    <p>Create, Read, Update, Delete</p> Signup and view all the answers

    Which statement correctly describes the purpose of the INSERT INTO statement?

    <p>It adds new rows of data to a table in the database.</p> Signup and view all the answers

    In SQL, what is the output of a SELECT query?

    <p>Data displayed in the form of a result table.</p> Signup and view all the answers

    What happens when a DELETE query is executed without a WHERE clause?

    <p>All records in the table are deleted.</p> Signup and view all the answers

    Which of the following is NOT a necessary component of an SQL INSERT INTO statement?

    <p>The database connection details.</p> Signup and view all the answers

    Which SQL clause can be used in DELETE statements to specify which records to remove?

    <p>WHERE</p> Signup and view all the answers

    What is the result of executing a SELECT statement without specifying any fields?

    <p>All fields of the table will be returned.</p> Signup and view all the answers

    If you want to combine multiple conditions in a DELETE query, which operators can you use?

    <p>AND and OR</p> Signup and view all the answers

    Study Notes

    Data Manipulation Language (DML)

    • DML is the subset of SQL used to manage data in a database.
    • DML includes the following operations: Create, Read, Update, and Delete (CRUD).

    Insert Query

    • Purpose: To add new records to a database table.
    • Syntax: INSERT INTO <table_name> (<column1>, <column2>, ... , <columnN>) VALUES (<value1>, <value2>, ... , <valueN>);
    • Example: INSERT INTO CUSTOMERS (ID, Name, Salary) VALUES (1, 'John', 50000);
    • Alternative Syntax (optional): INSERT INTO <table_name> VALUES (<value1>, <value2>, ... , <valueN>); (If values are provided for all columns in the table in the correct order)
    • Note: The order of values provided in the VALUES clause must match the order of the columns specified in the query.

    Select Query

    • Purpose: To retrieve data from a database table.
    • Syntax: SELECT <column1>, <column2>, ... , <columnN> FROM <table_name>;
    • Example: SELECT ID, Name, Salary FROM CUSTOMERS;
    • Note: You can select specific columns, all columns (SELECT *), or a combination thereof. The result is a result-set, which is a table representation of the data.

    Delete Query

    • Purpose: To remove existing records from a database table.
    • Syntax: DELETE FROM <table_name> WHERE <condition(s)>;
    • Examples:
      • DELETE FROM CUSTOMERS WHERE ID = 6; (Deletes a specific record)
      • DELETE FROM CUSTOMERS; (Deletes all records from the table)
    • Note: The use of a WHERE clause is crucial for deleting specific records.

    Update Query

    • Purpose: To modify the data of existing records in a database table.
    • Syntax: UPDATE <table_name> SET <column1> = <value1>, <column2> = <value2>, ... WHERE <condition(s)>;
    • Examples:
      • UPDATE CUSTOMERS SET ADDRESS = 'New Address' WHERE ID = 6; (Updates the address of a specific record)
      • UPDATE CUSTOMERS SET ADDRESS = 'New Address', SALARY = 60000; (Updates multiple columns for all records)
    • Note: Like DELETE, the use of WHERE clause is essential for specifying which records to modify.

    Where Clause

    • Purpose: To filter and restrict the data returned by the query.
    • Syntax: Used within SELECT, UPDATE, and DELETE statements.
    • Syntax (example): WHERE <condition(s)>
    • Examples (Within SELECT):
      • SELECT ID, Name FROM CUSTOMERS WHERE SALARY > 50000; (Returns data only for customers with salary greater than 50000)
      • SELECT ID, Name FROM CUSTOMERS WHERE City = 'London' AND Salary > 40000; (Returns data for customers who meet both conditions)
    • Notes:
      • The WHERE clause enables targeted data retrieval based on specified conditions.
      • It is used to filter and extract subsets of data from a table.
      • Use of comparison operators (>, <, =, >=, <=, !=), logical operators (AND, OR, NOT), and parentheses can further refine the conditions in WHERE clause.

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    Related Documents

    IT53_DBMS-3C.pdf

    Description

    Test your knowledge of Data Manipulation Language (DML) in SQL. This quiz covers essential operations such as Create, Read, Update, and Delete (CRUD), along with syntax for Insert and Select queries. Perfect for anyone looking to enhance their database management skills.

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