Jdbc basic query method

Jdbc basic query method

The three most basic interfaces for jdbc database operations are Statement PrepareStatment CallableStatement.

(1) Statement

createStatement() 

createStatement(int resultSetType, int resultSetConcurrency) 

CreateStatement(Int resultSetType, int resultSetConcurrency, int resultSetHoldability) (JDBC 3.0)

resultSetType-Result set type, which isResultSet. TYPE_FORWARD_ONLY (the result set cannot be rolled),ResultSet. TYPE_SCROLL_INSENSITIVE (rolling result set, affected by database updates))OrResultSet. TYPE_SCROLL_SENSITIVE (rolling result set, noAffected by database updates)One

resultSetConcurrency-Concurrency type; it isResultSet.CONCUR_READ_ONLY(Read-only result set) orResultSet. CONCUR_UPDATABLE (updatable result set).

resultSetHoldability-BelowResultSetConstant:ResultSet.HOLD_CURSORS_OVER_COMMIT(After modification is submitted, the result set is not closed) orResultSet. CLOSE_CURSORS_AT_COMMIT (disable the result set after modification is submitted)

Note: The use of resultSetType, resultSetConcurrency, and resultSetHoldability is limited.

Some databases do not support rolling result sets. They can update result sets, but do not close the result sets after the modification is submitted. You can use conn. getMetaData () to obtain the DataBaseMetaData object and determine whether the above functions are supported.

(2) PrepareStatement

prepareStatement(String sql) 

prepareStatement(String sql, int resultSetType, int resultSetConcurrency) 

prepareStatement(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability) 

 

prepareStatement(String sql, int autoGeneratedKeys) 

prepareStatement(String sql, int[] columnIndexes) 

prepareStatement(String sql, String[] columnNames) 

AutoGeneratedKeys can be Statement. RETURN_GENERATED_KEYS/NO_GENERATED_KEYS

Eg: PrepareStatement st = conn. prepareStatemnt (SQL, Statement. RETURN_GENERATED_KEYS );

ResultSet rs = st. getGeneratedKeys ();

If (rs. next ()){

Int key = ts. getInt (1 );

}

 

(3) CallableStatement

PrepareCall(String SQL)

prepareCall(String sql, int resultSetType, int resultSetConcurrency) 

prepareCall(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability)