You can change the data type of any column if all rows of the column contain nulls. However, if you change the data type of a column in a materialized view container table, then Oracle Database invalidates the corresponding materialized view.
US Economy. Definition: A stock market crash is when stock indexes lose more than 10% in a day or two. The broad indexes are the Dow Jones Industrial Average, the S&P 500, and the NASDAQ. The rapidity of the decline differentiates it from a stock market correction. That's a 10% loss over days, weeks or even months.
Why a Correction Is Not a Crash. A correction is different from a stock market crash, which is when stock prices plummet more than 10%, in just one day. Crashes are so frightening, they usually lead to a bear market. That's when the market goes on to drop another 10%, leading to a decline of 20% or more.