Oracle vs PostgreSQL Develop（18） - Boolean

在oracle和PG中都可以使用int类型模拟布尔类型，但通过JDBC接口（JDBC驱动，Oracle为11.2.0.4，PG为9.3）获取出来的值却不一致，这一点需要注意。
测试脚本

drop table tbl1;
create table tbl1(id int,c1 int);
insert into tbl1 values(1,1);
insert into tbl1 values(2,-1);
insert into tbl1 values(3,2);
insert into tbl1 values(4,0);

Java代码

package testPG;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
public class TestBoolean {
  public static void main(String[] args) {
    System.out.println("---------- PG -----------");
    try (Connection conn = DriverManager.getConnection("jdbc:postgresql://192.168.26.28:5432/testdb", "pg12",
        "pg12")) {
      TestBool(conn);
    } catch (SQLException se) {
      System.out.println(se.getMessage());
    } catch (Exception e) {
      e.printStackTrace();
    } finally {
    } // end try
    System.out.println("---------- Oracle -----------");
    try (Connection conn = DriverManager.getConnection("jdbc:oracle:thin:@192.168.1.18:1521:orcl", "test",
        "test")) {
      TestBool(conn);
    } catch (SQLException se) {
      System.out.println(se.getMessage());
    } catch (Exception e) {
      e.printStackTrace();
    } finally {
    } // end try
  }
  public static void TestBool(Connection conn) {
    try (PreparedStatement pstmt = conn.prepareStatement("SELECT id,c1 from tbl1");
        ResultSet rs = pstmt.executeQuery();) {
      conn.setAutoCommit(true);
      while (rs.next()) {
        int id = rs.getInt("id");
        int c1 = rs.getInt("c1");
        boolean b1 = rs.getBoolean("c1");
        System.out.println("id:" + id + ",c1:" + c1 + ",b1:" + b1);
      }
    } catch (SQLException se) {
      System.out.println(se.getMessage());
    } catch (Exception e) {
      e.printStackTrace();
    } finally {
    } // end try
  } // end
} // end Class

执行结果

---------- PG -----------
id:1,c1:1,b1:true
id:2,c1:-1,b1:false
id:3,c1:2,b1:false
id:4,c1:0,b1:false
---------- Oracle -----------
id:1,c1:1,b1:true
id:2,c1:-1,b1:true
id:3,c1:2,b1:true
id:4,c1:0,b1:false

使用JDBC，在PG中，只有1视为T，其他为F；而在Oracle中，只有0视为F，其他视为T。
但在PG中，如把int转换为boolean，则行为与Oracle一致。

[local]:5432 pg12@testdb=# create table tbl2(id int,c1 int);
CREATE TABLE
Time: 13.911 ms
[local]:5432 pg12@testdb=# insert into tbl2 values(1,1);
INSERT 0 1
Time: 5.091 ms
[local]:5432 pg12@testdb=# insert into tbl2 values(2,-1);
INSERT 0 1
Time: 2.653 ms
[local]:5432 pg12@testdb=# insert into tbl2 values(3,2);
INSERT 0 1
Time: 2.716 ms
[local]:5432 pg12@testdb=# insert into tbl2 values(4,0);
INSERT 0 1
Time: 2.625 ms
[local]:5432 pg12@testdb=# 
[local]:5432 pg12@testdb=# select id,c1 from tbl2;
 id | c1 
----+----
  1 |  1
  2 | -1
  3 |  2
  4 |  0
(4 rows)
Time: 3.183 ms
[local]:5432 pg12@testdb=# alter table tbl2 alter column c1 type boolean using c1::boolean;
ALTER TABLE
Time: 30.581 ms
[local]:5432 pg12@testdb=# select id,c1 from tbl2;
 id | c1 
----+----
  1 | t
  2 | t
  3 | t
  4 | f
(4 rows)
Time: 2.566 ms
[local]:5432 pg12@testdb=#