您可以看一下
INFORMATION_SCHEMA.COLUMNS:
if (select IS_NULLABLE from INFORMATION_SCHEMA.COLUMNS where TABLE_NAME='my_table' and COLUMN_NAME='end_date') = 'NO' begin ALTER TABLE my_table ALTER COLUMN end_date DATETIME NULLend

您可以看一下
INFORMATION_SCHEMA.COLUMNS:
if (select IS_NULLABLE from INFORMATION_SCHEMA.COLUMNS where TABLE_NAME='my_table' and COLUMN_NAME='end_date') = 'NO' begin ALTER TABLE my_table ALTER COLUMN end_date DATETIME NULLend