Best way to check for "empty or null value"

Best way to check for "empty or null value"

sql database postgresql null coalesce

database

Unable to cast object of type 'System.DBNull' to type 'System.String`

c# asp.net database null

database

Using COALESCE to handle NULL values in PostgreSQL

sql database postgresql null coalesce

database

Unique key with NULLs

mysql database null relational-model

database

Rails checking if a record exists in database

ruby-on-rails database null

database

How to check if a double is null?

java database null double

database

MySQL Integer 0 vs NULL

mysql sql database performance null

database

Should I use NULL or an empty string to represent no data in table column?

mysql database null

database

Concatenate with NULL values in SQL

sql database string null concatenation

database

Space used by nulls in database

sql sql-server database null

database

why is null not equal to null false

sql database null nullable

database

Can Microsoft store three-valued fields in a single bit?

sql-server database null boolean bit-fields

database

CASE WHEN NULL makes wrong result in SQLite?

sql database sqlite null

database

Do null values save storage space? [duplicate]

sql-server database null

database

testing inequality with columns that can be null

sql database null nullable informix

database