sql - (Oracle SQL)捕获唯一约束错误

Question

这是我的代码:

Declare
  violation_of_constraint EXCEPTION;
BEGIN
  -- (A FEW INSERTS HERE: A, B, C)
  SAVEPOINT X;
  -- (ANOTHER INSERT HERE: D)
  IF DUP_VAL_ON_INDEX THEN
    ROLLBACK TO X;
    COMMIT;
    RAISE violation_of_constraint;
  END IF;
EXCEPTION
  WHEN violation_of_constraint THEN
    DBMS_OUTPUT.PUT_LINE('Value already exists');
    COMMIT;
END;
/

当我运行它(从sql命令行)时，在第11行出现此错误:

expression is of wrong type (line 11 is "IF DUP_VAL_ON_INDEX THEN")

怎么了

Answer 1

您需要定义一个嵌套的PL/SQL块，并将EXCEPTION BLOCK中的异常作为WHEN DUP_VAL_ON_INDEX处理...

不应为IF DUP_VAL_ON_INDEX

Declare
violation_of_constraint EXCEPTION;
BEGIN
  BEGIN
  -- (A FEW INSERTS HERE: A, B, C)
  SAVEPOINT X;
  -- (ANOTHER INSERT HERE: D)
  EXCEPTION 
  WHEN DUP_VAL_ON_INDEX THEN
    ROLLBACK TO X;
    COMMIT;
    RAISE violation_of_constraint;
  END;
EXCEPTION
WHEN violation_of_constraint THEN
DBMS_OUTPUT.PUT_LINE('Value already exists');
COMMIT;
END;
/