“SQL ist null” Code-Antworten

Wählen Sie ohne Nullwerte SQL

SELECT column_names
FROM table_name
WHERE column_name IS NOT NULL;
Sergiu The Man

Nicht 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
);
Ankur

So finden Sie Spalten mit Nullwerten in SQL

declare @col varchar(255), @cmd varchar(max)

DECLARE getinfo cursor for
SELECT c.name FROM sys.tables t JOIN sys.columns c ON t.Object_ID = c.Object_ID
WHERE t.Name = 'ADDR_Address'

OPEN getinfo

FETCH NEXT FROM getinfo into @col

WHILE @@FETCH_STATUS = 0
BEGIN
    SELECT @cmd = 'IF NOT EXISTS (SELECT top 1 * FROM ADDR_Address WHERE [' + @col + '] IS NOT NULL) BEGIN print ''' + @col + ''' end'
    EXEC(@cmd)

    FETCH NEXT FROM getinfo into @col
END

CLOSE getinfo
DEALLOCATE getinfo
A5

SQL ist null

SELECT *
FROM Employee
WHERE email IS NOT NULL;
SAMER SAEID

SQL ist null und nicht null

SELECT *
FROM Employee
WHERE email IS NULL;
SAMER SAEID

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