From the course: Learning Oracle Database 19c
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How to use NULL values - Oracle Database Tutorial
From the course: Learning Oracle Database 19c
How to use NULL values
- [Instructor] Using null column values in Oracle Database 19c can be confusing at first, but once you understand the rules on how to manipulate them and use them, they become an effective way for your database to represent missing information. Null columns can't be used and manipulated like columns that contain values. If you try to add five plus null, you might expect to just get five. In Oracle Database 19c, any expression containing null evaluates to null. If you use SQL*Plus or SQLcl, a null result shows up as spaces, but in a SQL Developer worksheet, you'll get the string null in parentheses, which makes it much more obvious that you're getting a null value in the result. Here are a few of the common group functions you'll use in select statements. Count, average, min, max, standard deviation, and listagg. All of these group functions operate on a single column or expression, aggregate the values in that column with the group function, then return a single value. I'm going to…
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