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POUsing a NamedParamterJdbcTemplate object to specify a mysql field and value to query on
 

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  1. POUsing a NamedParamterJdbcTemplate object to specify a mysql field and value to query on
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    <p>I am currently in the process of learning the Java Spring Framework, and I am having difficulty understanding why the following query is failing to return any results from the database.</p> <p>I am ultimately trying to create a <code>where</code> method in my <code>OffersDAO</code> class that allows my to query on a specific field, for a specific value.</p> <pre><code>public List&lt;Offer&gt; where(String field, String value){ MapSqlParameterSource params = new MapSqlParameterSource(); params.addValue("field", field); params.addValue("value", value); String sql = "select * from offers where :field = :value"; return jdbc.query(sql, params, new RowMapper&lt;Offer&gt;(){ public Offer mapRow(ResultSet rs, int arg1) throws SQLException { Offer offer = new Offer(); offer.setId(rs.getInt("id")); offer.setName(rs.getString("name")); offer.setText(rs.getString("text")); offer.setEmail(rs.getString("email")); return offer; } }); } </code></pre> <p>I am able to successfully query the database for results when I specify the field explicitly, as follows:</p> <pre><code>String sql = "select * from offers where name = :value"; </code></pre> <p>Obviously there is something wrong with specifying the field name dynamically. My guess is it is most likely due to the fact that the <code>field</code> key is being inserted as a mysql string (with <code>''</code>), when in fact mysql expects a column name for the :field placeholder.</p> <p>My questions are as follows:</p> <ol> <li><p>Is there a way to accomplish what I am attempting to do above, using the jdbc NamedParameterJdbcTemplate class?</p></li> <li><p>If I cannot accomplish the above, by what means can I?</p></li> </ol> <p>Thank you</p> <p>Edit: No exceptions are thrown. In the case when I am attempting to supply the column name, a empty result set is returned.</p>
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    1. USPeter Kirby
    1. USPeter Kirby
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    1. This table or related slice is empty.
    1. COWhat is the exception in this case?
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      1. POUsing a NamedParamterJdbcTemplate object to specify a mysql field and value to query on
      1. USArsen Alexanyan
    2. COThere is no exception. Instead, only an empty ResultSet is returned.
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      1. POUsing a NamedParamterJdbcTemplate object to specify a mysql field and value to query on
      1. USPeter Kirby
    3. COAre You getting an empty result by running the concrette query?
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      1. POUsing a NamedParamterJdbcTemplate object to specify a mysql field and value to query on
      1. USArsen Alexanyan
 

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