SELECT column1, column2 FROM table_name WHERE [ conditions ] GROUP BY column1, column2 ORDER BY column1, column2
A subquery is a query within another query and embedded within the WHERE clause. A subquery is used to return data that will be used in the main query as a condition to further restrict the data to be retrieved. An example of this command is:
SELECT column_name [, column_name ] FROM table1 [, table2 ] WHERE column_name OPERATOR (SELECT column_name [, column_name ] FROM table1 [, table2 ] [WHERE])
We also touched on SQL I/O. As a side note, it would be helpful if the class covered more troubleshooting commands like DESCRIBE as well.
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