SQL Examples
SQL Filtered Query
Filtered SQL Query
Filtered query uses WHERE and LIKE with wildcards for precise results.
Understanding SQL Filtered Queries
SQL filtered queries are essential for retrieving specific data from a database. By using the WHERE clause, you can filter records to match certain conditions. Additionally, the LIKE operator, often paired with wildcards, enhances the ability to search for patterns within text fields.
Using the WHERE Clause
The WHERE clause is used to extract only those records that fulfill a specified condition. This makes it a powerful tool when you need to focus on particular data points.
In this example, the query selects all columns from the Customers table where the Country column's value is 'Germany'. This filters out any customers not located in Germany.
Using the LIKE Operator with Wildcards
The LIKE operator is used in a WHERE clause to search for a specified pattern in a column. Wildcards are often used with LIKE to enhance flexibility:
%: Represents zero or more characters._: Represents a single character.
This query selects all customers from the Customers table where the City name starts with an 'S' and ends with an 'n', such as 'San' or 'Syrn'.
In this example, the query retrieves products with names that have any single character followed by 'og', like 'Dog', 'Log', or 'Fog'. The underscore wildcard allows for this single character flexibility.
Combining WHERE and LIKE for Complex Queries
You can combine WHERE and LIKE with other conditions using logical operators like AND and OR to form complex queries.
This query returns all employees in the 'Sales' department whose email addresses end with '@example.com'. Combining conditions allows for more targeted data retrieval, enhancing query effectiveness.
Conclusion
SQL filtered queries with WHERE and LIKE offer powerful tools for precise data selection. By understanding how to use these features, you can efficiently manage and query your database to meet specific requirements.
SQL Examples
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