Learn SQL Database Programming

Fixing missing values

Another essential thing to look for is missing values to determine if you need to adjust the values or remove the data points. A row may be complete except for one column, so you may need to fix that one column of missing data. To see the count of NULL versus NON NULL values in a table, execute the following query:

USE lahmansbaseballdb; SELECT SUM(!ISNULL(birthyear)) AS birthyear_count,SUM(ISNULL(birthyear)) AS null_birthyear_countFROM people;

The results from the preceding query are shown in the following table:

birthyear_count	null_birthyear_count
19497	120

Looking at the results in the preceding table, you can see that there are some NULL values for birthyear. It may be valid that there are some NULL ...