Sélectionnez sans valeurs nuls 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
);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 getinfoSELECT *
FROM Employee
WHERE email IS NOT NULL;SELECT *
FROM Employee
WHERE email IS NULL;