The CASE statement goes through conditions and returns a value when the first condition is met (like an if-then-else statement). So, once a condition is true, it will stop reading and return the result. If no conditions are true, it returns the value in the ELSE clause.
If there is no ELSE part and no conditions are true, it returns NULL. Continue reading MySQL CASE Statement
The INSERT INTO SELECT statement copies data from one table and inserts it into another table.
The INSERT INTO SELECT statement requires that the data types in source and target tables matches.
Note: The existing records in the target table are unaffected. Continue reading MySQL INSERT INTO SELECT Statement
The ANY and ALL operators allow you to perform a comparison between a single column value and a range of other values.
The ANY operator:
ANY means that the condition will be true if the operation is true for any of the values in the range. Continue reading MySQL ANY and ALL Operators
The EXISTS operator is used to test for the existence of any record in a subquery.
The EXISTS operator returns TRUE if the subquery returns one or more records.
SELECT column_name(s) FROM table_name WHERE EXISTS (SELECT column_name FROM table_name WHERE condition);
The HAVING clause was added to SQL because the WHERE keyword cannot be used with aggregate functions.
SELECT column_name(s) FROM table_name WHERE condition GROUP BY column_name(s) HAVING condition ORDER BY column_name(s);
The GROUP BY statement groups rows that have the same values into summary rows, like “find the number of customers in each country”.
The GROUP BY statement is often used with aggregate functions (COUNT(), MAX(), MIN(), SUM(), AVG()) to group the result-set by one or more columns. Continue reading MySQL GROUP BY Statement
The UNION operator is used to combine the result-set of two or more SELECT statements.
SELECT statement within UNION must have the same number of columnsSELECT statement must also be in the same orderA self join is a regular join, but the table is joined with itself.
SELECT column_name(s) FROM table1 T1, table1 T2 WHERE condition;
T1 and T2 are different table aliases for the same table. Continue reading MySQL Self Join
The CROSS JOIN keyword returns all records from both tables (table1 and table2).
The RIGHT JOIN keyword returns all records from the right table (table2), and the matching records (if any) from the left table (table1).