Question

我想问的第一个问题是，使用多个where子句进行一次删除查询会更快，还是一个接一个地执行更快？如果是这样，那么如何使用多个where子句进行删除查询？提前谢谢！

Answer 1

您不能拥有多个WHERE子句，但可以使条件更复杂。

如果您的表格有FirstName和LastName，并且您要删除John Doe，Toby Steed和Linda Powers，请合并AND和OR这样的条件：

DELETE FROM MyTable
 WHERE ( FirstName = 'John' AND LastName = 'Doe' )
    OR ( FirstName = 'Toby' AND LastName = 'Steed' )
    OR ( FirstName = 'Linda' AND LastName = 'Powers' )

现在，如果你是用Java做的，你不应该（永远！）使用字符串连接来构建这样的SQL语句。使用PreparedStatement：

String sql = "DELETE FROM MyTable" +
             " WHERE ( FirstName = ? AND LastName = ? )" +
                " OR ( FirstName = ? AND LastName = ? )" +
                " OR ( FirstName = ? AND LastName = ? )";
try (PreparedStatement stmt = conn.prepareStatement(sql)) {
    stmt.setString(1, "John");
    stmt.setString(2, "Doe");
    stmt.setString(3, "Toby");
    stmt.setString(4, "Steed");
    stmt.setString(5, "Linda");
    stmt.setString(6, "Powers");
    stmt.executeUpdate();
}

Answer 2

尝试使用这可能是您问题的解决方案：

   db.delete(TABLE,
    KEY1 + "=? AND " + KEY2 + "=? AND " +
    KEY3 + "=? AND " + KEY4 + "=?",
    new String[] {param1, param2, param3, param4});

如果使用普通选择，请使用：

   db.delete(TABLE,"Column1='value1' and column2 like 'value2'...", null);

如何使用多个WHERE子句删除[SQLITE]

2 个答案: