1. Name DML commands.
2. What is the purpose of using queries?
3. Which clause of Select statement helps to display specific data?
4. Differentiate between Where and Orderby clause of SQL statements.
5. State the purpose of Update Command with the help of an example.
Answers
Answer:
1. Name DML commands.
Some commands of DML are:
SELECT – retrieve data from the a database.
INSERT – insert data into a table.
UPDATE – updates existing data within a table.
DELETE – deletes all records from a table, the space for the records remain.
MERGE – UPSERT operation (insert or update)
CALL – call a PL/SQL or Java subprogram.
2. What is the purpose of using queries?
Answer. Answer: a query is a request for data result , and for action of data . You can use a query to answer a simple question, to perform calculation, to combine data from different tables, or even to add, change or delete table data.
3. Which clause of Select statement helps to display specific data?
Answer: The SELECT statement has many optional clauses: FROM specifies which table to get the data. WHERE specifies which rows to retrieve. GROUP BY groups rows sharing a property so that an aggregate function can be applied to each group.
4. Differentiate between Where and Orderby clause of SQL statements.
Answer: In group by clause, the tuples are grouped based on the similarity between the attribute values of tuples. Whereas in order by clause, the result-set is sorted based on ascending or descending order.
5. State the purpose of Update Command with the help of an example.
"UPDATE Command". An UPDATE statement is used to directly change or modify the values stored in one or more fields in a specified record in a single table. UPDATE changes the values of the specified columns in all rows that satisfy the condition.