试题详情
- 单项选择题 The EMPLOYEES table has these columns:
Management wants to add a default value to the SALARY column. You plan to alter the table by using this SQL statement: 
What is true about your ALTER statement?（） A、Column definitions cannot be altered to add DEFAULT values.
B、A change to the DEFAULT value affects only subsequent insertions to the table.
C、Column definitions cannot be altered at add DEFAULT values for columns with a NUMBER data type.
D、All the rows that have a NULL value for the SALARY column will be updated with the value 5000.
- B
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