Wählen Sie ohne Nullwerte SQL
SELECT column_names
FROM table_name
WHERE column_name IS NOT NULL;
Sergiu The Man
SELECT column_names
FROM table_name
WHERE column_name IS NOT NULL;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
);CREATE TABLE Colleges (
college_id INT NOT NULL,
college_code VARCHAR(20),
college_name VARCHAR(50)
);SELECT *
FROM Employee
WHERE email IS NULL;select c_custkey, c_name, c_address from customer where c_custkey in (select o_orderkey from orders where o_orderkey IS NOT NULL)CREATE TABLE Colleges (
college_id INT NOT NULL,
college_code VARCHAR(20) NOT NULL,
college_name VARCHAR(50)
);