You’re going to have to do this as a separate query, for example: SELECT COUNT(1) FROM table_name Some JDBC drivers might tell you but this is optional behaviour and, more to the point, the driver may not know yet. This can be due to how the query is optimised eg two example execution strategies in … Read more
The answer is NO difference, but: I will always prefer to do the following. Always keep the Join Conditions in ON clause Always put the filter’s in where clause This makes the query more readable. So I will use this query: SELECT value FROM table1 INNER JOIN table2 ON table1.id = table2.id WHERE table1.id = … Read more
You can get columns number from ResultSetMetaData: Statement st = conn.createStatement(); ResultSet rs = st.executeQuery(query); ResultSetMetaData rsmd = rs.getMetaData(); int columnsNumber = rsmd.getColumnCount();
First, you should create Statement which can be move cursor by command: Statement stmt = con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY); Then retrieve the ResultSet as below: ResultSet rs = stmt.executeQuery(…); Move cursor to the latest row and get it: if (rs.last()) { int rows = rs.getRow(); // Move to beginning rs.beforeFirst(); … } Then rows variable will contains … Read more
Change your first statement to this pstat=con.prepareStatement(“select typeid from users where username=? and password=?”, ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_UPDATABLE); This way you can move forward and backward, so less things to worry about
Here is a self contained example of how to “execute the anonymous PL/SQL and get the resultset object” import java.sql.CallableStatement; import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.Types; import oracle.jdbc.OracleTypes; public class CallPLSQLBlockWithOneInputStringAndOneOutputStringParameterAndOneOutputCursorParameter { public static void main(String[] args) throws Exception { DriverManager.registerDriver(new oracle.jdbc.OracleDriver()); // Warning: this is a simple example program : In a … Read more
Warning: I’m going to get bombastic here, because this drives me crazy. 99%* of the time, it’s a ridiculous micro-optimization that people have some vague idea makes things ‘better’. This completely ignores the fact that, unless you’re in an extremely tight and busy loop over millions of SQL results all the time, which is hopefully … Read more
JDBC will simply name the columns by what is specified in the query – it doesn’t know about table names etc. You have two options: Option 1: Name the columns differently in the query, ie SELECT a.columnName as columnNameA, b.columnName as columnNameB, … from table1 a, table2 b where (WHATEVER) then in your java code … Read more
If you have access to the prepared statement that results in this resultset, you can use connection.prepareStatement(sql, ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY); This prepares your statement in a way that you can rewind the cursor. This is also documented in the ResultSet Javadoc In general, however, forwarding and rewinding cursors may be quite inefficient for large result sets. … Read more
Empty or not, but doing the following is always faulty: resultSet = statement.executeQuery(sql); string = resultSet.getString(1); // Epic fail. The cursor isn’t set yet. This is not a bug. This is documented behaviour. Every decent JDBC tutorial mentions it. You need to set the ResultSet’s cursor using next() before being able to access any data. … Read more