准备好的语句 java 中的 OR 子句

Question

Can we use OR clause in a PreparedStatement using java?

PreparedStatement stmt=con.prepareStatement("delete from emp where id=?");  
stmt.setString(1, "'MIKE' || 'ANDY'"); 

int i = stmt.executeUpdate();  
System.out.println(i + " records deleted");  

Answer 1

No. This is not raw text substitution and you can't drop in chunks of the query and expect them to get incorporated in. Each thing substituted for a placeholder gets sanitized, encoded, and quoted as a separate value.

But you can write it with 2 placeholders:

PreparedStatement stmt=con.prepareStatement(
    “delete from emp where id in (?, ?)”);
stmt.setString(1,"MIKE”);
stmt.setString(2, “ANDY”);

If you have a lot of values in the IN clause an alternative is to put those values in a table and join to it.

Answer 2

You can simply use two parameters.

PreparedStatement stmt=con.prepareStatement("delete from emp where id=? or id=?");
stmt.setString(1,"ANDY");
stmt.setString(2,"MIKE");