sql - 多次插入SQL oracle

Question

当您有标识列时，如何在 Oracle 12c 中使用 SQL 进行多次插入？

INSERT ALL
INTO Table1 (Column2) Values (1)
INTO Table1 (Column2) Values (2)
SELECT * FROM dual;

其中 Table1 将 column1 作为标识，会将标识列设置为具有相同的值，这违反了主键约束。

CREATE TABLE Table1 (
  Table1Id NUMBER GENERATED ALWAYS AS IDENTITY,
  column2 VARCHAR2(255),
  column3 NUMBER,
  PRIMARY KEY (Table1Id)
);

INSERT ALL
  INTO Table1 (column2, column3) VALUES ('a', '1')
  INTO Table1 (column2, column3) VALUES ('b', '2')
SELECT * FROM dual;

--SQL Error: ORA-00001: unique constraint violated

我做错了什么？

Answer 1

编辑添加了两个测试用例和一个可能的解决方法。

虽然Insert语句和insert all语句实际上是相同的传统插入语句。但当涉及到序列时，它们的工作方式有所不同。

测试用例 1:标识列

SQL> DROP TABLE table1 PURGE;

Table dropped.

SQL>
SQL> CREATE TABLE Table1 (
  2    Table1Id NUMBER GENERATED ALWAYS AS IDENTITY,
  3    column3 NUMBER,
  4    PRIMARY KEY (Table1Id)
  5  );

Table created.

SQL>
SQL> INSERT ALL
  2    INTO Table1 (column3) VALUES ('1')
  3    INTO Table1 (column3) VALUES ('2')
  4  SELECT * FROM dual;
INSERT ALL
*
ERROR at line 1:
ORA-00001: unique constraint (LALIT.SYS_C0010439) violated


SQL>

让我们看看幕后到底发生了什么 -

SQL> CREATE TABLE Table1 (
  2    Table1Id NUMBER GENERATED ALWAYS AS IDENTITY,
  3    column3 NUMBER,
  4    CONSTRAINT A UNIQUE (Table1Id)
  5  );

Table created.

SQL> INSERT ALL
  2    INTO Table1 (column3) VALUES (1)
  3    INTO Table1 (column3) VALUES (2)
  4  SELECT * FROM dual;
INSERT ALL
*
ERROR at line 1:
ORA-00001: unique constraint (LALIT.A) violated


SQL> SELECT * FROM table1;

no rows selected

SQL> ALTER TABLE table1
  2  DISABLE CONSTRAINT a;

Table altered.

SQL> INSERT ALL
  2    INTO Table1 (column3) VALUES (1)
  3    INTO Table1 (column3) VALUES (2)
  4  SELECT * FROM dual;

2 rows created.

SQL> SELECT * FROM table1;

  TABLE1ID    COLUMN3
---------- ----------
         2          1
         2          2

SQL>

因此，序列进行到 nextval，但是我们第一次执行“全部插入”时存在唯一约束违规。接下来，我们禁用唯一约束，随后的“插入全部”显示序列没有进展到 nextval，而是尝试插入重复键。

尽管 INSERT-INTO-SELECT 语句不会出现此问题。

SQL> INSERT INTO table1(column3) SELECT LEVEL FROM dual CONNECT BY LEVEL <=5;

5 rows created.

SQL>
SQL> SELECT * FROM table1;

  TABLE1ID    COLUMN3
---------- ----------
         2          1
         3          2
         4          3
         5          4
         6          5

SQL>

令人惊讶的是，根据元数据，序列应该自动进入 nextval，但使用 Insert All 语句时不会发生这种情况。

SQL> SELECT COLUMN_NAME,
  2    IDENTITY_COLUMN,
  3    DATA_DEFAULT
  4  FROM user_tab_cols
  5  WHERE table_name   ='TABLE1'
  6  AND IDENTITY_COLUMN='YES';

COLUMN_NAME     IDENTITY_COLUMN DATA_DEFAULT
--------------- --------------- ------------------------------
TABLE1ID        YES             "LALIT"."ISEQ$$_94458".nextval

SQL>

测试用例 2:显式使用序列

无论使用标识列还是使用显式序列，INSERT ALL 的工作方式都是相同的。

SQL> DROP SEQUENCE s;

Sequence dropped.

SQL>
SQL> CREATE SEQUENCE s;

Sequence created.

SQL>
SQL> DROP TABLE t PURGE;

Table dropped.

SQL>
SQL> CREATE TABLE t (
  2    ID NUMBER,
  3    text VARCHAR2(50),
  4    CONSTRAINT id_pk PRIMARY KEY (ID)
  5  );

Table created.

SQL>
SQL> INSERT ALL
  2    INTO t VALUES (s.nextval, 'a')
  3    INTO t VALUES (s.nextval, 'b')
  4    INTO t VALUES (s.nextval, 'c')
  5    INTO t VALUES (s.nextval, 'd')
  6  SELECT * FROM dual;
INSERT ALL
*
ERROR at line 1:
ORA-00001: unique constraint (LALIT.ID_PK) violated


SQL>
SQL> SELECT * FROM T;

no rows selected

SQL>
SQL> ALTER TABLE t
  2    DISABLE CONSTRAINT id_pk;

Table altered.

SQL> INSERT ALL
  2    INTO t VALUES (s.nextval, 'a')
  3    INTO t VALUES (s.nextval, 'b')
  4    INTO t VALUES (s.nextval, 'c')
  5    INTO t VALUES (s.nextval, 'd')
  6  SELECT * FROM dual;

4 rows created.

SQL> SELECT * FROM T;

        ID TEXT
---------- ----------------------------------------
         2 a
         2 b
         2 c
         2 d

SQL>

可能的解决方法 - 使用 ROW LEVEL 触发器

SQL> CREATE OR REPLACE TRIGGER t_trg
  2      BEFORE INSERT ON t
  3      FOR EACH ROW
  4      WHEN (new.id IS NULL)
  5      BEGIN
  6        SELECT s.NEXTVAL
  7        INTO   :new.id
  8        FROM   dual;
  9      END;
 10  /

Trigger created.

SQL> truncate table t;

Table truncated.

SQL> INSERT ALL
  2    INTO t (text) VALUES ('a')
  3    INTO t (text) VALUES ('b')
  4    INTO t (text) VALUES ('c')
  5    INTO t (text) VALUES ('d')
  6  SELECT * FROM dual;

4 rows created.

SQL> SELECT * FROM t;

        ID TEXT
---------- -------------------------
         3 a
         4 b
         5 c
         6 d

SQL>