Warning: strtotime() [function.strtotime]: It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'America/New_York' for 'EST/-5.0/no DST' instead in /home/frodr/public_html/msofficetuneup.com/wp-includes/functions.php on line 35
Warning: date() [function.date]: It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'America/New_York' for 'EST/-5.0/no DST' instead in /home/frodr/public_html/msofficetuneup.com/wp-includes/functions.php on line 107
Warning: date() [function.date]: It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'America/New_York' for 'EST/-5.0/no DST' instead in /home/frodr/public_html/msofficetuneup.com/wp-includes/functions.php on line 109
Warning: date() [function.date]: It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'America/New_York' for 'EST/-5.0/no DST' instead in /home/frodr/public_html/msofficetuneup.com/wp-includes/functions.php on line 111
Warning: date() [function.date]: It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'America/New_York' for 'EST/-5.0/no DST' instead in /home/frodr/public_html/msofficetuneup.com/wp-includes/functions.php on line 112
Feb
Warning: strtotime() [function.strtotime]: It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'America/New_York' for 'EST/-5.0/no DST' instead in /home/frodr/public_html/msofficetuneup.com/wp-includes/functions.php on line 35
Warning: date() [function.date]: It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'America/New_York' for 'EST/-5.0/no DST' instead in /home/frodr/public_html/msofficetuneup.com/wp-includes/functions.php on line 107
Warning: date() [function.date]: It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'America/New_York' for 'EST/-5.0/no DST' instead in /home/frodr/public_html/msofficetuneup.com/wp-includes/functions.php on line 109
Warning: date() [function.date]: It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'America/New_York' for 'EST/-5.0/no DST' instead in /home/frodr/public_html/msofficetuneup.com/wp-includes/functions.php on line 111
Warning: date() [function.date]: It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'America/New_York' for 'EST/-5.0/no DST' instead in /home/frodr/public_html/msofficetuneup.com/wp-includes/functions.php on line 112
05
No, this isn’t a detour into feel-good Dr. Phil psychology. Database nerds use the labels parent and child to identify the two tables in a relationship, and keep track of which one’s which.
Here’s the analogy. As you no doubt know, in the real world a parent can have any number of children. However, a child has exactly one set of parents. The same rule works for databases. In the bobblehead database, a single manufacturer record can be linked to any number of doll records. However, each doll record refers to a single manufacturer. So according to the database world’s strange sociology, Manufacturers is a parent table and Dolls is a child table. They’re linked by a parent-child relationship.
Tip: Don’t think too hard about the parent-child analogy. It’s not a perfect match with biological reality. For example, in the bobblehead database, you may create a manufacturer that doesn’t link to any dolls (in other words, a parent with no children). You still call that record a parent record, because it’s part of the parent table.
It’s important to realize that you can’t swap the parent and child tables around without changing your relationship. It’s incorrect to suggest that Dolls is the parent table and Manufacturers is the child table. You can see that such a suggestion would break the parent-child analogy: a single doll can’t have more than one manufacturer, and a manufacturer isn’t limited to creating a single doll. In order to prevent problems and all-around fuzzy thinking, you need to know exactly which table’s the parent and which one’s the child.
Tip: If you have trouble identifying which table’s the parent, there’s a simple rule to steer you right. The child table always contains a piece of identifying information from the parent table. In the bobblehead database, the Dolls table contains the ManufacturerID field. On the other hand, the Manufacturer table doesn’t have any doll information.
If you have database-savvy friends, you’ll hear the term parent-child relationship quite a bit. The same relationship’s also called a one-to-many relationship (where one is the parent and many represents the children, because a single parent record in one table can link to several child records in the other). It’s the most common relationship, but not the only oneyou’ll learn about two other types in Section 5.3 and Section 5.3.2.
Note: Relationships are so common in modern-day databases that software like Access is often described as a relational database management system (RDBMS). A database without relationships is about as common as a beachfront resort in Ohio.
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