Clause in SQL
? Clause in SQL
A clause is a component or part of an SQL statement that performs a specific function. SQL statements are made up of various clauses that work together to query, modify, or manage data.
? Common SQL Clauses and Their Purpose
| Clause | Purpose |
|---|---|
SELECT | Specifies the columns or expressions to retrieve from the database. |
FROM | Specifies the table(s) to query data from. |
WHERE | Filters rows based on a specified condition. |
GROUP BY | Groups rows sharing a property so aggregate functions can be applied. |
HAVING | Filters groups based on a condition (used with GROUP BY). |
ORDER BY | Sorts the result set by specified column(s). |
JOIN | Combines rows from two or more tables based on a related column. |
LIMIT / TOP | Restricts the number of rows returned. |
INSERT INTO | Adds new rows to a table. |
UPDATE | Modifies existing rows. |
DELETE | Removes rows from a table. |
ALTER TABLE | Changes the structure of a table (add, drop columns, etc.). |
CREATE TABLE | Creates a new table. |
Example: Using Several Clauses Together
SELECT employee_name, salaryFROM employeesWHERE salary > 50000GROUP BY employee_name, salaryHAVING COUNT(*) > 1ORDER BY salary DESCLIMIT 10;Here,
SELECT,FROM,WHERE,GROUP BY,HAVING,ORDER BY, andLIMITare all clauses.
Summary
A clause is a building block of SQL queries.
Each clause serves a specific role to filter, sort, group, or modify data.
SQL statements often combine multiple clauses to perform complex operations.
If you want, I can explain any specific clause in detail!
