1 answers

4 points

Asked by:

758

I have trouble uring JdbcTemplate query() function getting single result from ResultSet.

This is exception I got:

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java.sql.SQLException: Before start of result set

This is stack trace:

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java.sql.SQLException: Before start of result set
    at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:129) ~[mysql-connector-java-8.0.22.jar:8.0.22]
    at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97) ~[mysql-connector-java-8.0.22.jar:8.0.22]
    at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:89) ~[mysql-connector-java-8.0.22.jar:8.0.22]
    at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:63) ~[mysql-connector-java-8.0.22.jar:8.0.22]
    at com.mysql.cj.jdbc.result.ResultSetImpl.checkRowPos(ResultSetImpl.java:492) ~[mysql-connector-java-8.0.22.jar:8.0.22]
    at com.mysql.cj.jdbc.result.ResultSetImpl.getObject(ResultSetImpl.java:1299) ~[mysql-connector-java-8.0.22.jar:8.0.22]
    at com.mysql.cj.jdbc.result.ResultSetImpl.getLong(ResultSetImpl.java:823) ~[mysql-connector-java-8.0.22.jar:8.0.22]
    at com.zaxxer.hikari.pool.HikariProxyResultSet.getLong(HikariProxyResultSet.java) ~[HikariCP-4.0.3.jar:?]
    at chat.MessagesService.lambda$fetchMessages$1(MessagesService.java:215) ~[classes/:?]
    at org.springframework.jdbc.core.JdbcTemplate$1QueryStatementCallback.doInStatement(JdbcTemplate.java:453) ~[spring-jdbc-5.3.13.jar:5.3.13]
    at org.springframework.jdbc.core.JdbcTemplate.execute(JdbcTemplate.java:381) ~[spring-jdbc-5.3.13.jar:5.3.13]
    at org.springframework.jdbc.core.JdbcTemplate.query(JdbcTemplate.java:465) ~[spring-jdbc-5.3.13.jar:5.3.13]
    ...

SQL query I used:

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SELECT COUNT(*)
FROM `messages` m
WHERE (m.`removal_time` IS NULL)

My java source code:

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// import org.springframework.jdbc.core.JdbcTemplate;
​
// @Autowire
// private JdbcTemplate jdbcTemplate;
​
public Long getCount() {
    String sqlQuery = "SELECT COUNT(*)                 \n" +
                      "FROM `messages` m               \n" +
                      "WHERE (m.`removal_time` IS NULL)\n";
​
    return this.jdbcTemplate.query(sqlQuery, (resultSet) -> (Long) resultSet.getLong(1));
}

1 answer

5 points

Answered by:

Root-ssh

178180

In the above case you need to call resultSet.next() function before calling resultSet.getLong(1) function.

Fixed source code:

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public Long getCount() {
    String sqlQuery = "SELECT COUNT(*)                 \n" +
                      "FROM `messages` m               \n" +
                      "WHERE (m.`removal_time` IS NULL)\n";
​
    long rowsCount = this.jdbcTemplate.query(sqlQuery, (resultSet) -> {
        if (resultSet.next()) {
            return resultSet.getLong(1);
        }
        return 0L;
    });
​
    return rowsCount;
}

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Spring Boot 2 - JdbcTemplate throws: java.sql.SQLException: Before start of result set

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