试题详情
- 单项选择题The EMPLOYEES table has these columns:LAST_NAME VARCHAR2(35) SALARY NUMBER(8,2) HIRE_DATE DATEManagement wants to add a default value to the SALARY column. You plan to alter the table by using this SQL statement:ALTER TABLE EMPLOYEES MODIFY (SALARY DEFAULT 5000);Which 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 to 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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