sql is not empty string code example

Example 1: t sql null or empty string

select * from vendor
where isnull(vendor_email,'') = ''

Example 2: sql check for null and empty string

IF ISNULL(@param) OR @param = '' THEN doSomething...

Example 3: NOT NULL SQL

By default, a column can hold NULL values.
The NOT NULL constraint enforces a column to NOT accept NULL values.
This enforces a field to always contain a value, which means that you cannot insert a new record, or update a record without adding a value to this field.

Sql NOT NULL in creating a table
CREATE TABLE Persons (
    ID int NOT NULL,
    LastName varchar(255) NOT NULL,
    FirstName varchar(255) NOT NULL,
    Age int
);