Data Query Language (DQL) is used to retrieve data from a database. It helps users to view and analyze the stored data without modifying it.
1. What is DQL?
DQL is mainly used for fetching data from tables. The most important command in DQL is SELECT.
2. SELECT Command
The SELECT command is used to retrieve data from one or more tables.
Example:
SELECT * FROM Students;
This command displays all records from the Students table.
3. Selecting Specific Columns
Example:
SELECT Name, Age FROM Students;
This retrieves only the Name and Age columns.
4. Using WHERE Condition
Example:
SELECT * FROM Students WHERE Age > 20;
This shows only students whose age is greater than 20.
5. Sorting Data
Example:
SELECT * FROM Students ORDER BY Age ASC;
This sorts the data in ascending order of age.
6. Key Points
- DQL is used only for retrieving data
- It does not modify database structure or data
- SELECT is the main command
- Supports filtering, sorting, and selecting specific columns
Conclusion
DQL is essential for accessing and analyzing data in a database. It allows users to retrieve meaningful information efficiently.
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Tags
MS SQL Server