JDBC Basic Query method

When JDBC operates the database, the most basic three interfaces 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 is ResultSet.TYPE_FORWARD_ONLY(不可滚动结果集) , ResultSet.TYPE_SCROLL_INSENSITIVE(可滚动结果集，受数据库更新影响的 ) or ResultSet.TYPE_SCROLL_SENSITIVE(可滚动结果集，不 受数据库更新影响的) one of

resultSetConcurrency-concurrency type; it is ResultSet.CONCUR_READ_ONLY (read-only result set) or ResultSet.CONCUR_UPDATABLE (可更新结果集) one.

resultSetHoldability- ResultSet one of the following constants: ResultSet.HOLD_CURSORS_OVER_COMMIT (after committing the modification, do not close the result set) orResultSet.CLOSE_CURSORS_AT_COMMIT (提交修改后，关闭结果集)

Description: The use of resultsettype,resultsetconcurrency,resultsetholdability is limited.

Some databases do not support scrollable result sets, you can update the result set, and you do not close the result set after committing the modification. The DatabaseMetaData object can be obtained by conn.getmetadata () to determine whether the above features 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 used for 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)

JDBC Basic Query method