What Are Not Null Constraints? A Video Quiz

You can mark a column as mandatory by specifying it as not null.
But how much do you know about these constraints?
Find out in this video quiz!
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The Magic of SQL with Chris Saxon
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[@pritamswarupajena1194]

Yesterday my query was running fine. Today it is executing long time what could be possible reason? Kindly answer where can we start diagnosing?

[@TheMagicofSQL]

Start by looking at the execution plan & comparing it to the previous one (if available).
The following playlist shows you how to get started with the plan in SQL Developer
czcams.com/video/SH6os4zxvgM/video.html