Question

这句话给我带来以下异常的问题是什么？

    s.addBatch("CREATE TABLE category ( id  SMALLINT NOT NULL GENERATED ALWAYS AS IDENTITY \n" +
            "\t(START WITH 0, INCREMENT BY 1), title  VARCHAR(100))\n" );
    s.addBatch("CREATE TABLE task (id SMALLINT NOT NULL GENERATED ALWAYS AS IDENTITY \n" +
            "\t(START WITH 0, INCREMENT BY 1), title VARCHAR(100), cat_id INT, visible BOOLEAN, " +
            "deprecated BOOLEAN" +
            "CONSTRAINT fk_cat_id FOREIGN KEY (cat_id)\n" +
            "\tREFERENCES category(id))");
    s.executeBatch();

第一个addBatch在我正在运行的代码中被注释，因为我之前创建了表。事实上，如果我没有评论第一批，我会收到一个错误，说该表已经存在并且看到this question我知道这是检查derby中是否存在表的唯一方法。根据{{3}}

，我看到我的陈述是正确的

java.sql.BatchUpdateException: Syntax error: Encountered "fk_cat_id" at line 2, column 119.
    at org.apache.derby.impl.jdbc.Util.newBatchUpdateException(Unknown Source)
    at org.apache.derby.impl.jdbc.EmbedStatement.executeLargeBatch(Unknown Source)
    at org.apache.derby.impl.jdbc.EmbedStatement.executeBatch(Unknown Source)
    at model.DBConnection.createTables(DBConnection.java:48)
    at model.DBConnection.<init>(DBConnection.java:33)
    at model.DBConnection.<clinit>(DBConnection.java:10)
    at test.DBTest.main(DBTest.java:11)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:120)
Caused by: java.sql.SQLSyntaxErrorException: Syntax error: Encountered "fk_cat_id" at line 2, column 119.
    at org.apache.derby.impl.jdbc.SQLExceptionFactory40.getSQLException(Unknown Source)
    at org.apache.derby.impl.jdbc.Util.generateCsSQLException(Unknown Source)
    at org.apache.derby.impl.jdbc.TransactionResourceImpl.wrapInSQLException(Unknown Source)
    at org.apache.derby.impl.jdbc.TransactionResourceImpl.handleException(Unknown Source)
    at org.apache.derby.impl.jdbc.EmbedConnection.handleException(Unknown Source)
    at org.apache.derby.impl.jdbc.ConnectionChild.handleException(Unknown Source)
    at org.apache.derby.impl.jdbc.EmbedStatement.execute(Unknown Source)
    at org.apache.derby.impl.jdbc.EmbedStatement.executeBatchElement(Unknown Source)
    ... 11 more
Caused by: java.sql.SQLException: Syntax error: Encountered "fk_cat_id" at line 2, column 119.
    at org.apache.derby.impl.jdbc.SQLExceptionFactory.getSQLException(Unknown Source)
    at org.apache.derby.impl.jdbc.SQLExceptionFactory40.wrapArgsForTransportAcrossDRDA(Unknown Source)
    ... 19 more
Caused by: ERROR 42X01: Syntax error: Encountered "fk_cat_id" at line 2, column 119.
    at org.apache.derby.iapi.error.StandardException.newException(Unknown Source)
    at org.apache.derby.impl.sql.compile.ParserImpl.parseStatement(Unknown Source)
    at org.apache.derby.impl.sql.GenericStatement.prepMinion(Unknown Source)
    at org.apache.derby.impl.sql.GenericStatement.prepare(Unknown Source)
    at org.apache.derby.impl.sql.conn.GenericLanguageConnectionContext.prepareInternalStatement(Unknown Source)
    ... 13 more

Answer 1

sql语句中有很多错误！

没有为该类别定义主键。
任务中category和cat_id中的ID类型不匹配。
由于PM77-1注意到空格不受尊重。

无论如何，工作代码如下：

s.addBatch("CREATE TABLE category ( id  INT NOT NULL GENERATED ALWAYS AS IDENTITY \n" +
        "\t(START WITH 0, INCREMENT BY 1), title  VARCHAR(100), " +
        "\tCONSTRAINT category_pk_id PRIMARY KEY (id))\n" );
s.addBatch("CREATE TABLE task (id SMALLINT NOT NULL GENERATED ALWAYS AS IDENTITY \n" +
        "\t(START WITH 0, INCREMENT BY 1), title VARCHAR(100), cat_id INT, visible BOOLEAN, " +
        "deprecated BOOLEAN," +
        "\t CONSTRAINT task_pk_id PRIMARY KEY (id)," +
        "\t CONSTRAINT fk_cat_id FOREIGN KEY (cat_id)\n" +
        "\t REFERENCES category(id))");

但是代码中仍然会出现错误，这些操作不是原子操作，如果发生了一个错误，而下一个错误则第一个没有回滚。它没有解决。

德比外键约束

1 个答案: