-- To Check if column contains 'NULL' values, use the 'IS NULL' condition. -- Example, select all the rows where the column "column_name" is NULL. -- Query will return all rows where the `column_name` has `NULL` values. SELECT * FROM table_name WHERE column_name IS NULL; #-----------------------------------------------------------------------# -- To check if a column doesn't contain `NULL` values, Use the `IS NOT NULL` condition. -- Select all rows where the column "column_name" IS NOT NULL. -- Query will return all rows where `column_name` doesn't have `NULL` values. SELECT * FROM table_name WHERE column_name IS NOT NULL; #------------------------------------------------------------------------# # Combine Example -- Select rows where "column1" is NULL and "column2" is NOT NULL. -- Return rows where `column` is `NULL` and `column2` is NOT NULL. -- Can also combine these condition with other clauses, such as `where`, `AND`, `OR`, etc.. SELECT * FROM table_name WHERE column1 IS NULL AND column2 IS NOT NULL; SELECT column_name FROM table_name WHERE column_name IS NOT NULL;# IS NULL SELECT column_names FROM table_name WHERE column_name IS NULL; # IS NOT NULL SELECT column_names FROM table_name WHERE column_name IS NOT NULL;ALTER TABLE ime_tabele ALTER stolpec SET NOT NULL;# IS NULL SELECT column_names FROM table_name WHERE column_name IS NULL; # IS NOT NULL SELECT column_names FROM table_name WHERE column_name IS NOT NULL;Tests for empty (NULL) values. Example: Returns users that haven’t given a contact number. SELECT * FROM users WHERE contact_number IS NULL;SELECT * FROM my_table WHERE my_column IS NOT NULL;SELECT * FROM table_name WHERE column_name IS NOT NULL;CREATE TABLE example_table ( id INT NOT NULL, name VARCHAR(50) NOT NULL, age INT );SELECT * FROM Employee WHERE email IS NOT NULL;