1z0-071 Oracle Database 12c SQL 第69题 数据字典user_constraints

Q69. Evaluate the following SELECT statement and view the Exhibit to examine its output:

SELECT constraint_name, constraint_type, search_condition, r_constraint_name, delete_rule, status FROM user_constraints WHERE table_name = ORDERS
Which two statements are true about the output? (Choose two.)

A. In the second column, indicates a check constraint.
B. The STATUS column indicates whether the table is currently in use.
C. The R_CONSTRAINT_NAME column gives the alternative name for the constraint.
D. The column DELETE_RULE decides the state of the related rows in the child table when the corresponding row is deleted from the parent table.

Correct Answer: AD

对于 B 选项，status 是指约束的状态。

对于 C 选项，R_CONSTRAINT_NAME 指的关联的父表中主键约束的名称。

利用数据字典user_constraints可以查看用户模式下的表的约束信息

利用数据字典user_cons_columns可以查看每张表定义的约束是在哪一列上

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