Final answer:
In database queries, to find rows with a NULL value in a certain column, one should use the 'IS NULL' condition rather than '= NULL'. The '=' operator does not work with NULL values in databases; instead 'IS NULL' properly identifies rows with unknown or missing values in the specified column.
Step-by-step explanation:
To find rows containing a NULL value in a specified column within a database, the correct search condition is IS NULL, not = NULL. In a database, NULL represents an unknown or missing value, and comparing anything to NULL using the equal operator = will result in unknown, which is effectively false.
For example, in SQL, to find all rows where a particular column, let's call it ColumnName, is NULL, you would write:
SELECT * FROM TableName WHERE ColumnName IS NULL;
This SQL query will return all rows from the table TableName where the ColumnName has a NULL value.