About a SELECT command to execute in my MysQL Database

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  • Carcinosi
    New Member
    • Nov 2009
    • 1

    About a SELECT command to execute in my MysQL Database

    Hello,

    I have a MySQL 5.0 Database used for management of my service, with 13 tables.

    The two tables most important now are "customers" and "cust_packages" .

    The table "customers" has one column "cust_email ". This column has e-mails of customers of the my service.

    The table named "cust_packa ges" has one column "cpack_cancelda te". This column has the date of canceled accounts, for example '2008-04-03'. If the account is not canceled, so this column has '0000-00-00'.

    Both tables "customers" and "cust_packa ges" have "cust_custn r" and "cpack_user nr" respectively with interconnected values.

    These columns have an identification number exclusive for each customer.

    For example, I have one customer with the number '110002' in the column "cust_custn r" of the table "customers" . The same number is in the column "cpack_user nr" of the table "cust_packages" .

    I want to select all e-mails of customers with canceled accounts.

    But there is a problem. The same customer may have two accounts...the same number may appear two or more times in the colum "cpack_user nr" of the table "cust_packages" . For example, the customer '110002' in the past cancelled his account, but recently he opened another account. Because this, the same number 110002 appear two times in the column "cpack_user nr" of the table "cust_packages" . I need only exclusive customers with canceled accounts.

    So, I want to select all e-mails of customers with canceled accounts AND ONLY for customers which appear ONE TIME in the colum "cpack_user nr" of the table "cust_packages" .

    Thanks.
  • code green
    Recognized Expert Top Contributor
    • Mar 2007
    • 1726

    #2
    What about DISTINCT or using GROUP BY?

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