Java 如何在调用postgresql函数时获取动态结果集
我用PostgreSQL编写了一个带有if和else if条件的存储过程。在每个条件下,都有返回不同结果的不同查询。如何使用Java 如何在调用postgresql函数时获取动态结果集,java,postgresql,stored-procedures,jdbc,callable-statement,Java,Postgresql,Stored Procedures,Jdbc,Callable Statement,我用PostgreSQL编写了一个带有if和else if条件的存储过程。在每个条件下,都有返回不同结果的不同查询。如何使用resultset.getString()方法在Java中访问结果 存储过程: CREATE FUNCTION public."testDynamicReturn"(_tagId character varying) RETURNS ??? -- what should be written in the place of ??? LANGUAGE 'plp
resultset.getString()
方法在Java中访问结果
存储过程:
CREATE FUNCTION public."testDynamicReturn"(_tagId character varying)
RETURNS ??? -- what should be written in the place of ???
LANGUAGE 'plpgsql'
AS $BODY$
BEGIN
IF _tagId == 'stu' then
RETURN query
SELECT "StudentRollNo.","StudentName","GuardianName" FROM public."DetailsOfStudents";
ELSE if _tagId == 'teach' then
RETURN query
SELECT "TeacherName","TeacherAddress" FROM public."DetailsOfTeachers";
END;
$BODY$;
Java代码:
public static void main(String[] args) {
Connection connection = DBUtility.getDBConnection();
String sp = "{ call \"testDynamicReturn\"(?)}";
try {
CallableStatement statement = connection.prepareCall(sp);
statement.setString(1, "stu");
statement.execute();
ResultSet resultSet = statement.getResultSet();
while (resultSet.next()) {
String a = resultSet.getString(???);
System.out.println(a);
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
如果我将“stu”作为存储过程参数发送,则结果将是:
--------------------------------------------
StudentRollNo.| StudentName | GuardianName |
--------------------------------------------
15600223596 | John | Doe |
--------------------------------------------
------------------------------
TeacherName | TeacherAddress |
------------------------------
Adam | New york |
------------------------------
如果我将“teach”作为存储过程参数发送,则结果将是:
--------------------------------------------
StudentRollNo.| StudentName | GuardianName |
--------------------------------------------
15600223596 | John | Doe |
--------------------------------------------
------------------------------
TeacherName | TeacherAddress |
------------------------------
Adam | New york |
------------------------------
请回答如何实现上述功能。以下是功能:
CREATE OR REPLACE FUNCTION public.testDynamicReturn(_tagId character varying)
RETURNS TABLE (out_rollNum character varying, out_name character varying, out_gaurdian character varying)
AS
$func$
BEGIN
IF _tagId = 'stu' then
--validate your select, ensure it works independently
RETURN QUERY SELECT "StudentRollNo.","StudentName","GuardianName" FROM public."DetailsOfStudents";
END IF;
IF _tagId = 'teach' then
--validate your select, ensure it works independently
RETURN QUERY SELECT "StudentRollNo.","StudentName", CAST (null AS character varying) "GuardianName" FROM public."DetailsOfStudents";
END IF;
END
$func$ LANGUAGE plpgsql;
PreparedStatement statement = conn.prepareStatement("select * from public.testDynamicReturn('stu')");
ResultSet resultSet = statement.executeQuery();
while (resultSet.next()) {
//can give column name
String rollNum= resultSet.getString("out_rollNum");
String name= resultSet.getString("out_name");
//will be null for 'stu'but you already know
String gaurdian= resultSet.getString("out_gaurdian");
}
下面是调用此动态函数的代码:
CREATE OR REPLACE FUNCTION public.testDynamicReturn(_tagId character varying)
RETURNS TABLE (out_rollNum character varying, out_name character varying, out_gaurdian character varying)
AS
$func$
BEGIN
IF _tagId = 'stu' then
--validate your select, ensure it works independently
RETURN QUERY SELECT "StudentRollNo.","StudentName","GuardianName" FROM public."DetailsOfStudents";
END IF;
IF _tagId = 'teach' then
--validate your select, ensure it works independently
RETURN QUERY SELECT "StudentRollNo.","StudentName", CAST (null AS character varying) "GuardianName" FROM public."DetailsOfStudents";
END IF;
END
$func$ LANGUAGE plpgsql;
PreparedStatement statement = conn.prepareStatement("select * from public.testDynamicReturn('stu')");
ResultSet resultSet = statement.executeQuery();
while (resultSet.next()) {
//can give column name
String rollNum= resultSet.getString("out_rollNum");
String name= resultSet.getString("out_name");
//will be null for 'stu'but you already know
String gaurdian= resultSet.getString("out_gaurdian");
}
以下是函数:
CREATE OR REPLACE FUNCTION public.testDynamicReturn(_tagId character varying)
RETURNS TABLE (out_rollNum character varying, out_name character varying, out_gaurdian character varying)
AS
$func$
BEGIN
IF _tagId = 'stu' then
--validate your select, ensure it works independently
RETURN QUERY SELECT "StudentRollNo.","StudentName","GuardianName" FROM public."DetailsOfStudents";
END IF;
IF _tagId = 'teach' then
--validate your select, ensure it works independently
RETURN QUERY SELECT "StudentRollNo.","StudentName", CAST (null AS character varying) "GuardianName" FROM public."DetailsOfStudents";
END IF;
END
$func$ LANGUAGE plpgsql;
PreparedStatement statement = conn.prepareStatement("select * from public.testDynamicReturn('stu')");
ResultSet resultSet = statement.executeQuery();
while (resultSet.next()) {
//can give column name
String rollNum= resultSet.getString("out_rollNum");
String name= resultSet.getString("out_name");
//will be null for 'stu'but you already know
String gaurdian= resultSet.getString("out_gaurdian");
}
下面是调用此动态函数的代码:
CREATE OR REPLACE FUNCTION public.testDynamicReturn(_tagId character varying)
RETURNS TABLE (out_rollNum character varying, out_name character varying, out_gaurdian character varying)
AS
$func$
BEGIN
IF _tagId = 'stu' then
--validate your select, ensure it works independently
RETURN QUERY SELECT "StudentRollNo.","StudentName","GuardianName" FROM public."DetailsOfStudents";
END IF;
IF _tagId = 'teach' then
--validate your select, ensure it works independently
RETURN QUERY SELECT "StudentRollNo.","StudentName", CAST (null AS character varying) "GuardianName" FROM public."DetailsOfStudents";
END IF;
END
$func$ LANGUAGE plpgsql;
PreparedStatement statement = conn.prepareStatement("select * from public.testDynamicReturn('stu')");
ResultSet resultSet = statement.executeQuery();
while (resultSet.next()) {
//can give column name
String rollNum= resultSet.getString("out_rollNum");
String name= resultSet.getString("out_name");
//will be null for 'stu'but you already know
String gaurdian= resultSet.getString("out_gaurdian");
}
这不是我的答案。我的问题是如何通过java编写SP和access。SP不返回任何值。我问的是SP的语法。你的查询说你已经编写了SP,你正在研究如何访问它。这不是我的答案。我的问题是如何通过java编写SP和access。SP不返回任何值。我在询问SP的语法。您的查询说您已经编写了SP,并且正在研究如何访问它。