HAVING AND SubSELECT IN MYSQL

Hello world… welcome to my blog at “We Are Knowledge”… In here you will getting many IT knowledge, like as : PHP, MYSQL, Visual Basic, PASCAL, and other program languages.. likely this article want discuss about “MYSQL”. You will know ?? let’s do read my article…

MYSQL is database.. And used for saving the data. But now, I want giving you IT knowledge about “HAVING and SubSELECT in MYSQL”…

1. HAVING

Having in mysql is query command provided by MYSQL for the number of items (types) for each record. Usually we are just using GROUP BY for classifying. we can use when having the same query command group by.

Example without “having”

SELECT hardware.id_hardware, COUNT(price.id_product) as  total

FROM hardware, price

WHERE hardware.id_hardware = price.id_product

AND total >= 5

GROUP BY hardware.id_hardware

To result :

| id_hardware  | total    |

|1                        | 1          |

|2                        |1           |

|3                        |1           |

|4                        |1           |

|5                        |1           |

Example with “having”

SELECT hardware.id_hardware, COUNT(price.id_product) as  total

FROM hardware, price

WHERE hardware.id_hardware = price.id_product

GROUP BY hardware.id_hardware

HAVING total >=5

To result :

| id_hardware     | total     |

|1                           | 7          |

|2                           |5           |

|3                           |5           |

|4                           |9           |

|5                           |6           |

1. SubSELECT

 SubSELECT is query command there is a command that allows select in the select command.

Example 3 :

SELECT [table name 1, table name 2]

FROM [database name 1, database name 2]

(

SELECT table name 1, table name 2]

FROM [database name 1, database name 2]

)

WHERE [condition] ;

Example 4 :

SELECT id_hardware , name_hardware, price_hardware

FROM hardaware

WHERE name_hardware =

(

SELECT price_hardware

FROM  hardware

WHERE price_hardware >= 2500

)

ORDER BY price_hardware;

To Result :

|id_hardware |name_hardware| price_hardware|

|3                      | MODEM            |2900                    |

|6                      |MEMORY          |3200                    |

|10                    |HARD DISK      |3250                    |

|11                    | VGA                  | 6000                   |

Ok.. just it..

I hope you understand…

See you later