Snowflake Alter Data Type
alter table t1 alter c4 set data type varchar(50)
Garo_Gorille
alter table t1 alter c4 set data type varchar(50)alter table TABLE_NAME add column TEMP_COLUMN TIMESTAMP_LTZ(9);
update TABLE_NAME t1
set t1.TEMP_COLUMN = TO_TIMESTAMP_LTZ(t2.TIMESTAMP_NTZ_COLUMN_NAME)
from TABLE_NAME t2
where t1.TEMP_COLUMN = t2.TIMESTAMP_NTZ_COLUMN_NAME
// if you don't want troubles create a new copy of table and use SWAP WITH instead
alter table aws_config rename column TIMESTAMP_NTZ_COLUMN_NAME to TIMESTAMP_NTZ_COLUMN_NAME_OLD;
alter table aws_config rename column TEMP_COLUMN to TIMESTAMP_NTZ_COLUMN_NAME;
alter table aws_config drop column TIMESTAMP_NTZ_COLUMN_NAME_OLD