JDBC ResultSet returns 数据库中存储的值为空

Question

我尝试使用 Java 从 Vertica 数据库中获取结果集。但它 returns null.

SQL查询：

SELECT to_char(SUM(my_column)) FROM my_table
UNION ALL SELECT to_char(123) FROM dual

SQL 数据库客户端结果：

201198184560.13000
123

sql_result

Java代码：

PreparedStatement ps;
ps = connection.prepareStatement(sqlQuery);
ResultSet rs = ps.executeQuery();

while (rs.next()) {
    System.out.println("Inside loop...");
    String str = rs.getString(1);
    Float f = rs.getFloat(1);
    Double d = rs.getDouble(1);
    Object obj = rs.getObject(1);
    System.out.println("String: " + str + ", float: " + f + ", double: " + d + ", obj: " + obj);
}

java 控制台中的结果：

Inside loop...
String: null, float: 0.0, double: 0.0, obj: null
Inside loop...
String: 123, float: 123.0, double: 123.0, obj: 123

我做错了什么？为什么结果集 returns 为空？如何在 java 控制台中打印所有结果集？

更新1：在 rs.next():

之前调试

rs = {S4ForwardResultSet@1015} 
 m_logger = {DSILogger@1028} 
 m_resultMetaData = {S4ResultSetMetaData@1045} 
 m_currentRow = 0
 m_currentStream = null
 m_isOpen = true
 m_resultSet = {VResultSet@1046} 
 m_resultSetColumns = {ArrayList@1038}  size = 1
 m_warningListener = {SWarningListener@1047} 
 m_wasLastValueNull = false
 m_cachedDataWrappers = {ArrayList@1048}  size = 1
 m_cursorPosition = {CursorPosition@1049} "BEFORE_FIRST"
 m_columnNameIndexes = {ArrayList@1050}  size = 1
 m_numColumns = 1
 m_parentStatement = {VerticaJdbc4PreparedStatementImpl@996} 
 m_jdbcVersion = {JDBCVersion@1030} "JDBC4"
 m_streamBufferSize = 32000

更新2：第一次 rs.next() 调试：

rs = {S4ForwardResultSet@1013} 
 m_logger = {DSILogger@1014} 
 m_resultMetaData = {S4ResultSetMetaData@1015} 
 m_currentRow = 1
 m_currentStream = null
 m_isOpen = true
 m_resultSet = {VResultSet@1016} 
 m_resultSetColumns = {ArrayList@1017}  size = 1
 m_warningListener = {SWarningListener@1018} 
 m_wasLastValueNull = true
 m_cachedDataWrappers = {ArrayList@1019}  size = 1
 m_cursorPosition = {CursorPosition@1078} "AT_FIRST"
 m_columnNameIndexes = {ArrayList@1021}  size = 1
 m_numColumns = 1
 m_parentStatement = {VerticaJdbc4PreparedStatementImpl@996} 
 m_jdbcVersion = {JDBCVersion@1022} "JDBC4"
 m_streamBufferSize = 32000

调试 rs.next() 第二次：

m_logger = {DSILogger@1014} 
m_resultMetaData = {S4ResultSetMetaData@1015} 
m_currentRow = 2
m_currentStream = null
m_isOpen = true
m_resultSet = {VResultSet@1016} 
m_resultSetColumns = {ArrayList@1017}  size = 1
m_warningListener = {SWarningListener@1018} 
m_wasLastValueNull = false
m_cachedDataWrappers = {ArrayList@1019}  size = 1
m_cursorPosition = {CursorPosition@1087} "AT_LAST"
m_columnNameIndexes = {ArrayList@1021}  size = 1
m_numColumns = 1
m_parentStatement = {VerticaJdbc4PreparedStatementImpl@996} 
m_jdbcVersion = {JDBCVersion@1022} "JDBC4"
m_streamBufferSize = 32000

更新 3：SQL 看起来像这样：

with prov as
 (select ...
    from ...
    join ...
      on ...               
   where ...)
,
debet as
 (select prov....
    from prov
   where ...
   group by prov....
  ),
kredit as
 (select prov....
    from prov
   where ...
   group by prov....
  )

select 
    TO_CHAR(SUM(debet.sum_debet_rur)) SSS
from
    kredit full join debet 
    on ...
where (debet...) and (debet....)    

UNION ALL SELECT TO_CHAR(123) SSS from dual

Answer 1

问题出在我的 SQL-查询中。

我的 JavaApp 从包含 --comments 的文件中获取 SQL-query。在我的 JavaApp 将其转换为字符串并发送到数据库后。

在 Vertica 中，您可以使用查询检查您的查询：

select * from query_requests
order by start_timestamp desc

谢谢！

JDBC ResultSet returns 数据库中存储的值为空

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