SQL從其他Table Update欄位

UPDATE Table1
SET FLD1=O.FLD1
FROM Table2 O
WHERE KEY=O.KEY

SQL檢查欄位是否存在

IF EXISTS (SELECT * FROM sys.columns C WHERE name='FLD1'
AND EXISTS(SELECT * FROM sys.tables WHERE name='Table1' AND type='U' AND object_id=C.object_id))
PRINT 'EXISTS'
ELSE
PRINT 'NOT EXISTS'