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    PRO100 5.20 Professional Library

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    PDF files, browse Downloads, Manuals & Support information. Non-commercial license enables you to use this software on any number of computers within the office .Q:

    SQL Foreign Key Enforce

    I’m looking for the right way to enforce that a database won’t insert a row unless I explicitly tell it that there is a foreign key constraint between these two tables.
    Currently I’m using a trigger that I wrote when insert data to the table which contains the foreign key. So first I check to make sure that there is no row in this other table, then I insert the row.
    Is this a good way of doing this? Does the dbms support a something like check constraint that automatically enforces this rule?


    If you’re using MySQL, you could rely on the INFORMATION_SCHEMA as described in this answer:

    Otherwise, based on your description, the solution is to use a BEFORE INSERT TRIGGER.


    Passing string which is not null or empty

    Now this is a somewhat “traditional” way of trying to pass a string to a function.
    In a given function, I need to be able to accept a string. I don’t want to accept an empty string but I don’t want to accept null either because if I pass null to a function, the function will return the default value “”. Is there anyway of setting this up better?
    public void OnLoad(object sender, EventArgs args)

    I’m not worried about what this function does, just that it accepts a string.


    You can use one of the overloads of Paramaterized.
    // A string was passed in
    MyFunction(“A string was passed in”);

    // A nullable string was passed in

    // A string was passed in, and is not null or an empty string
    MyFunction(“A string was passed in”, “A string was passed in”);

    // A string was passed in
    MyFunction(“A string was passed in”);

    class Program
    static void Main(string[]


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