關於dbutils中QueryRunner看批量刪除語句batch

//批量刪除

public void delBooks(String[] ids) throws SQLException {
QueryRunner qr = new QueryRunner(C3P0Utils.getDataSource());
Object[][] params = new Object[ids.length][];//高維也就是行數確定執行sql語句的次數，低維也就是列數是給？賦值
for (int i = 0; i < params.length; i++) {//循環行數,決定SQL語句執行的次數
params[i] = new Object[]{ids[i]};//給低維也就是列數“？”賦值，每行只給一列賦值，決定每條SQL語句的參數個數
}
qr.batch("delete from books where id=?", params);
}

源碼實現：

public int[] batch(String sql, Object[][] params) throws SQLException {
Connection conn = this.prepareConnection();

return this.batch(conn, true, sql, params);
}

private int[] batch(Connection conn, boolean closeConn, String sql, Object[][] params) throws SQLException {
if (conn == null) {
throw new SQLException("Null connection");
}

if (sql == null) {
if (closeConn) {
close(conn);
}
throw new SQLException("Null SQL statement");
}

if (params == null) {
if (closeConn) {
close(conn);
}
throw new SQLException("Null parameters. If parameters aren't need, pass an empty array.");
}

PreparedStatement stmt = null;
int[] rows = null;
try {
stmt = this.prepareStatement(conn, sql);

for (int i = 0; i < params.length; i++) {
this.fillStatement(stmt, params[i]);
stmt.addBatch();
}
rows = stmt.executeBatch();

} catch (SQLException e) {
this.rethrow(e, sql, (Object[])params);
} finally {
close(stmt);
if (closeConn) {
close(conn);
}
}

return rows;
}

解讀: 因為params是一個二維數組, 所以往preparedStatement中賦值的時候使用了for循環, 然后通過preparedstatement.addBatch() 進行批量添加, 然后執行executeBatch()進行操作.

 

本文轉自：https://www.cnblogs.com/wang-meng/p/5525389.html