Mastering SQL Concepts

To retrieve matching records from two or more tables.

To create a new table from existing tables.

To update records in a single table.

To delete records from two tables.

LEFT JOIN includes all rows from the left table; RIGHT JOIN includes all rows from the right table.

LEFT JOIN excludes rows from the left table; RIGHT JOIN excludes rows from the right table.

LEFT JOIN only returns matching rows; RIGHT JOIN returns all rows from both tables.

LEFT JOIN and RIGHT JOIN are identical in functionality.

TOTAL(*)

SUM(*)

AVG(*)

COUNT(*)

GET UNIQUE(column_name) FROM table_name;

SELECT ALL column_name FROM table_name;

SELECT DISTINCT column_name FROM table_name;

SELECT column_name FROM table_name WHERE DISTINCT;

UPDATE table_name WHERE condition;

SET column1 = value1, column2 = value2 UPDATE table_name;

UPDATE table_name SET column1 = value1;

UPDATE table_name SET column1 = value1, column2 = value2 WHERE condition;

The WHERE clause specifies the columns to be deleted.

The WHERE clause is used to update records in a DELETE statement.

The WHERE clause determines which records to delete in a DELETE statement.

The WHERE clause determines the order of deletion in a DELETE statement.

A CROSS JOIN returns the Cartesian product of two tables.

A CROSS JOIN is used to merge two tables into one without any duplication.

A CROSS JOIN filters rows based on specific conditions.

A CROSS JOIN combines rows from two tables based on a common column.

Use AND and OR operators to combine conditions.

Combine conditions by using GROUP BY only.

Use SELECT and FROM clauses to combine conditions.

Conditions can only be combined in subqueries.

To filter rows based on specific conditions.

To group rows that have the same values in specified columns and perform aggregate calculations on them.

To sort rows in ascending or descending order.

To create new tables from existing data.

Aggregate functions can only be used with numeric data types; scalar functions can handle any data type.

Scalar functions return multiple values from multiple inputs; aggregate functions return a single value from a single row.

Aggregate functions return a single value from multiple rows; scalar functions return a single value from a single input.

Aggregate functions operate on individual rows; scalar functions operate on entire tables.