Java查询执行，读取ResultSet行时出现的问题

Question

我正在编写简单的Java代码，我必须在Postgresql数据库上执行一个SQL查询。这个数据库的结果(我手动检查过)是一个由一个列和两个整数组成的简单表，如下所示：

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我的问题是我找不到阅读这两行的方法。我的阅读代码是：

_conn.setReadOnly(假)； ( _conn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE，ResultSet.CONCUR_READ_ONLY)； _stmt.setFetchSize(100)； List< Short > lista =新的List< Short >()； _rs =_stmt.executeQuery(查询)； 时间(_rs.next()) { Lista.add((短)_rs.getInt(1))； }

这段代码只读取第一行，但没有办法让它读取第二行。短列表"lista“总是包含一个元素。这就像如果ResultSet不继续读取第二行.

如何读取这两行？

编辑：我尝试过使用ArrayList，但它不起作用。我为_conn连接和_stmt语句添加了代码部分。以下是查询：

            SELECT COUNT(bffK.biological_function_feature_oid) 
        FROM biological_function_feature AS bff 
        INNER JOIN biological_function_feature_unfolded AS bffu 
        ON bff.biological_function_feature_oid = bffu.term_oid 
        INNER JOIN (    SELECT DISTINCT ON (g.gene_oid, bffu.ancestor_oid) g.gene_oid AS ance_gene, bffu.ancestor_oid AS ance_oid, mf.feature_name AS feature_name, mf.feature_id AS feature_id, ef.name AS evidence, qf.name AS qualifier  
                FROM gene2biological_function_feature AS g2bff  
                INNER JOIN biological_function_feature AS bff  
                ON g2bff.biological_function_feature_oid = bff.biological_function_feature_oid   
                INNER JOIN biological_function_feature_unfolded AS bffu  
                ON bffu.term_oid = bff.biological_function_feature_oid  
                INNER JOIN metadata.feature AS mf ON bff.feature_type = mf.feature_id   
                INNER JOIN gene AS g ON g2bff.gene_oid = g.gene_oid  
                LEFT JOIN flag.evidence_flags AS ef ON g2bff.evidence = ef.id  
                LEFT JOIN flag.qualifier_flags AS qf ON g2bff.qualifier = qf.id     
                LEFT JOIN flag.inferred_flags AS fif ON fif.id = g2bff.inferred    
                WHERE g.gene_oid=(4060969) 
                AND (bff.is_obsolete NOT IN ('t') OR bff.is_obsolete IS NULL)    
                AND (g.is_obsolete NOT IN ('t') OR g.is_obsolete IS NULL)
                AND distance=1   
                 UNION 
                SELECT DISTINCT ON (g.gene_oid, bff.biological_function_feature_oid)   
                g.gene_oid AS ance_gene, bff.biological_function_feature_oid AS ance_oid, 
                mf.feature_name AS feature_name, mf.feature_id AS feature_id,  
                ef.name AS evidence, 
                qf.name AS qualifier   
                FROM gene2biological_function_feature AS g2bff  
                INNER JOIN biological_function_feature AS bff  
                ON g2bff.biological_function_feature_oid = bff.biological_function_feature_oid    
                INNER JOIN metadata.feature AS mf ON bff.feature_type = mf.feature_id    
                INNER JOIN gene AS g ON g2bff.gene_oid = g.gene_oid  
                LEFT JOIN flag.evidence_flags AS ef ON g2bff.evidence = ef.id  
                LEFT JOIN flag.qualifier_flags AS qf ON g2bff.qualifier = qf.id     
                LEFT JOIN flag.inferred_flags AS fif ON fif.id = g2bff.inferred    
                WHERE g.gene_oid=(4060969) 
                AND (bff.is_obsolete NOT IN ('t') OR bff.is_obsolete IS NULL)   
                AND (g.is_obsolete NOT IN ('t') OR g.is_obsolete IS NULL)  
                AND ef.name NOT IN ('IEA', 'ND') 
            ) 
        AS unf ON unf.ance_oid = bffu.ancestor_oid 
        INNER JOIN gene AS gK on gk.Gene_oid=ance_gene 
        INNER JOIN biological_function_feature AS bffK 
        ON bffK.biological_function_feature_oid = bffu.ancestor_oid 
        LEFT JOIN flag.evidence_flags AS efK  
        ON evidence = efK.name 
        LEFT JOIN flag.qualifier_flags AS qfK  
        ON qualifier = qfK.name 
        WHERE bffu.distance=1 AND (bff.biological_function_feature_oid) IN (217538)
        AND evidence NOT IN ('IEA', 'ND')   
        UNION 
        SELECT COUNT(bffK.biological_function_feature_oid) 
        FROM biological_function_feature AS bff 
        INNER JOIN biological_function_feature_unfolded AS bffu 
        ON bff.biological_function_feature_oid = bffu.term_oid 
        INNER JOIN (    SELECT DISTINCT ON (g.gene_oid, bffu.ancestor_oid) g.gene_oid AS ance_gene, bffu.ancestor_oid AS ance_oid, mf.feature_name AS feature_name, mf.feature_id AS feature_id, ef.name AS evidence, qf.name AS qualifier  
                FROM gene2biological_function_feature AS g2bff  
                INNER JOIN biological_function_feature AS bff  
                ON g2bff.biological_function_feature_oid = bff.biological_function_feature_oid   
                INNER JOIN biological_function_feature_unfolded AS bffu  
                ON bffu.term_oid = bff.biological_function_feature_oid  
                INNER JOIN metadata.feature AS mf ON bff.feature_type = mf.feature_id   
                INNER JOIN gene AS g ON g2bff.gene_oid = g.gene_oid  
                LEFT JOIN flag.evidence_flags AS ef ON g2bff.evidence = ef.id  
                LEFT JOIN flag.qualifier_flags AS qf ON g2bff.qualifier = qf.id     
                LEFT JOIN flag.inferred_flags AS fif ON fif.id = g2bff.inferred    
                WHERE g.gene_oid=(4060969) 
                AND (bff.is_obsolete NOT IN ('t') OR bff.is_obsolete IS NULL)    
                AND (g.is_obsolete NOT IN ('t') OR g.is_obsolete IS NULL)
                AND distance=1   
                 UNION 
                SELECT DISTINCT ON (g.gene_oid, bff.biological_function_feature_oid)   
                g.gene_oid AS ance_gene, bff.biological_function_feature_oid AS ance_oid, 
                mf.feature_name AS feature_name, mf.feature_id AS feature_id,  
                ef.name AS evidence, 
                qf.name AS qualifier   
                FROM gene2biological_function_feature AS g2bff  
                INNER JOIN biological_function_feature AS bff  
                ON g2bff.biological_function_feature_oid = bff.biological_function_feature_oid    
                INNER JOIN metadata.feature AS mf ON bff.feature_type = mf.feature_id    
                INNER JOIN gene AS g ON g2bff.gene_oid = g.gene_oid  
                LEFT JOIN flag.evidence_flags AS ef ON g2bff.evidence = ef.id  
                LEFT JOIN flag.qualifier_flags AS qf ON g2bff.qualifier = qf.id     
                LEFT JOIN flag.inferred_flags AS fif ON fif.id = g2bff.inferred    
                WHERE g.gene_oid=(4060969) 
                AND (bff.is_obsolete NOT IN ('t') OR bff.is_obsolete IS NULL)   
                AND (g.is_obsolete NOT IN ('t') OR g.is_obsolete IS NULL)  
                AND ef.name IN ('IEA', 'ND') 
            ) 
        AS unf ON unf.ance_oid = bffu.ancestor_oid 
        INNER JOIN gene AS gK on gk.Gene_oid=ance_gene 
        INNER JOIN biological_function_feature AS bffK 
        ON bffK.biological_function_feature_oid = bffu.ancestor_oid 
        LEFT JOIN flag.evidence_flags AS efK  
        ON evidence = efK.name 
        LEFT JOIN flag.qualifier_flags AS qfK  
        ON qualifier = qfK.name 
        WHERE bffu.distance=1 AND (bff.biological_function_feature_oid) IN (217538)
        AND evidence IN ('IEA', 'ND')

Answer 1

列表是一个接口，请尝试使用类似于ArrayList的方法

List< Short > lista = new ArrayList< Short >();

_rs = _stmt.executeQuery(query);

     while (_rs.next()) {

lista.add((short)_rs.getShort(1));

}

Answer 2

List是一个接口，因此不能直接实例化，而不能像ArrayList那样使用它的实现之一。还请注意，count是PG中的关键字，因此避免使用关键字作为标识符。工作解决方案：

pst = connection.prepareStatement("SELECT * FROM demo");
List<Short> lista = new ArrayList<Short>();
rs = pst.executeQuery();

while (rs.next()) {
   lista.add((short)rs.getInt(1));
}

Answer 3

这似乎不是语法上的问题。在对数据库运行查询时，也会得到一行吗？也许您也可以发布SQL查询。