使用 apache Derby 的 WHERE 子句上的 SQL 语法错误

Question

对于下面的 SQL 选择语句； -

resultSet = statement.executeQuery("SELECT SS100.ORDERS.ORDER_ID, SS100.ORDERS.ORDER_NUMBER," +" SS100.ORDERS.PERSON_ID, SS100.PERSON.FIRST_NAME"+
"FROM  PERSON, ORDERS " +
"WHERE SS100.PERSON.PERSON_ID = SS100.ORDERS.PERSON_ID " );

我在 WHERE 关键字上遇到语法错误 - 转储如下：-

 java.sql.SQLSyntaxErrorException: Syntax error: Encountered "WHERE" at line 1, column 126.
    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.executeQuery(Unknown Source)
    at Database.orderQuery(Database.java:146)
    at MainApp.main(MainApp.java:19)

Caused by: java.sql.SQLException: Syntax error: Encountered "WHERE" at line 1, column 126.
at org.apache.derby.impl.jdbc.SQLExceptionFactory.getSQLException(Unknown Source)
at org.apache.derby.impl.jdbc.SQLExceptionFactory40.wrapArgsForTransportAcrossDRDA(Unknown Source)... 10 more

我尝试过使用 alias 语句，但在 '.' 上出现错误。点运算符。我显然在做一些根本错误的事情，但我现在看不到，有人可以帮忙吗？

Answer 1

看这里：

resultSet = statement.executeQuery("SELECT ..." +... + " SS100.ORDERS.PERSON_ID, SS100.PERSON.FIRST_NAME"+
    "FROM  PERSON, ORDERS " +

"SS100.PERSON.FIRST_NAME" 和 "FROM" 之间没有空格。

这可以通过始终以空格开头来轻松解决：

resultSet = statement.executeQuery("SELECT ..." +... + " SS100.ORDERS.PERSON_ID, SS100.PERSON.FIRST_NAME"+
    " FROM  PERSON, ORDERS " +
    " WHERE ..."

Answer 2

这个字符串的串联会变成

"SELECT SS100.ORDERS.ORDER_ID, SS100.ORDERS.ORDER_NUMBER," +" SS100.ORDERS.PERSON_ID, SS100.PERSON.FIRST_NAME"+

"来自人，订单" + "哪里 SS100.PERSON.PERSON_ID = SS100.ORDERS.PERSON_ID "

SELECT SS100.ORDERS.ORDER_ID, SS100.ORDERS.ORDER_NUMBER, SS100.ORDERS.PERSON_ID,
SS100.PERSON.FIRST_NAMEFROM  PERSON, ORDERS WHERE SS100.PERSON.PERSON_ID =
SS100.ORDERS.PERSON_ID

问题在于FIRST_NAME 和FROM 加入的位置。在FIRST_NAME后面加一个空格，sql应该可以正常运行了。

但是，您真的应该问自己为什么要这样做。如果您知道要连接的值，为什么不从一个字符串开始。