南大通用GBase 8s JDBC 中 ROW 类型的应用

用户6279947182622025-10-25 11:01

原文链接：www.gbase.cn/community/p...

更多精彩内容尽在南大通用GBase技术社区，南大通用致力于成为用户最信赖的数据库产品供应商。

GBase 8s 提供了对 ROW 类型的支持，这使得在 JDBC 中处理嵌套数据结构变得更为灵活。

ROW 类型是一种复合数据类型，可以包含多个字段，每个字段都有自己的数据类型。在 GBase 8s 中，ROW 类型可以用于定义表的列、程序变量、语句变量以及例程返回值。通过 ROW 类型，可以更直观地表示和操作复杂的数据结构。

准备各个row类型：

sql 复制代码 
CREATE ROW TYPE r1_t (i INT, b BOOLEAN);
CREATE ROW TYPE r2_t (f FLOAT, s MULTISET(INT8 NOT NULL), i INT);
CREATE ROW TYPE fullname_t (first CHAR(20), last CHAR(20));
CREATE ROW TYPE person_t (id INT, name fullname_t, age INT);

对应的几个SQLData实现类（只放核心代码）

typescript 复制代码 
public class r1_t implements SQLData {
   int     int_col;
   boolean bool_col;
   public String toString() {
       String str = "int_col: " + int_col + "    bool_col: " + bool_col;
       return (str);
   }
}
ini 复制代码 
public class r2_t implements SQLData {
   double     dbl_col;
   int        int_col;
   Collection  mset_col;
public void readSQL(SQLInput stream, String typeName) throws SQLException {
       dbl_col = stream.readDouble();
       mset_col = (Collection) ((IfmxComplexSQLInput) stream).readObject();
       int_col = stream.readInt();
   }
   public void writeSQL(SQLOutput stream) throws SQLException {
       stream.writeDouble(dbl_col);
       ((IfmxComplexSQLOutput) stream).writeObject(mset_col);
       stream.writeInt(int_col);
   }
public String toString() {
       String str = "dbl_col: " + dbl_col + "\n";
       str += "                int_col: " + int_col + "\n";
       str += "                mset_col: \n";
       Iterator it = mset_col.iterator();
       Object element;
       while (it.hasNext()) {
           element = it.next();
           str += "\t\t\telement: " + element + "\n";
       }
       return (str);
   }
}
typescript 复制代码 
public class fullname implements SQLData {
   public String  first;
   public String  last;
}
public class person implements SQLData {
   public int      id;
   public fullname name;
   public int      age;
   public void readSQL(SQLInput stream, String type) throws SQLException {
   sql_type = type;
   id = stream.readInt();
   name = (fullname) stream.readObject();
   age = stream.readInt();
}
public void writeSQL(SQLOutput stream) throws SQLException {
   stream.writeInt(id);
   stream.writeObject(name);
   stream.writeInt(age);
}
public String toString() {
         String s = "person:";
         s += "id: " + id + "\n";
         s += "     name: " + name.toString() + "\n";
         s += "     age: " + age + "\n";
         return s;
     }
}

例1：

ini 复制代码 
fetching a named row into a SQLData object
s = "create table teachers (person person_t, dept char (20))";
stmt.executeUpdate(s);
s = "insert into teachers values ('row(100, row(Bill, Smith), 27)', 'physics')";
stmt.executeUpdate(s);
java.util.Map map = conn.getTypeMap();
map.put("fullname_t", Class.forName("com.jdbc.demo.fullname"));
map.put("person_t", Class.forName("com.jdbc.demo.person"));
pstmt = conn.prepareStatement("select person from teachers");
rs = pstmt.executeQuery();
while (rs.next()) {
   person who = (person) rs.getObject(1);    
   System.out.println("row: " + who.toString());
}

输出：

sql 复制代码 
row: person:id: 100
   name: fullname: first: Bill                 last: Smith               
   age: 27

例2：

ini 复制代码 
insert java object(SQLData) into a named row column
s = "create table teachers (person person_t, dept char (20))";
stmt.executeUpdate(s);
java.util.Map map = conn.getTypeMap();
map.put("fullname_t", Class.forName("com.jdbc.demo.fullname"));
map.put("person_t", Class.forName("com.jdbc.demo.person"));
person who = new person();
fullname name = new fullname();
name.last = "Jones";
name.first = "Sarah";
who.id = 567;
who.name = name;
who.age = 17;
String s = "insert into teachers values (?, 'physics')";
pstmt = conn.prepareStatement(s);
pstmt.setObject(1, who);
int rowcount = pstmt.executeUpdate();
pstmt = conn.prepareStatement("select person::lvarchar from teachers");
rs = pstmt.executeQuery();
while (rs.next()) {
   String s = rs.getString(1);
System.out.println("lvarchar: " + s);
}

输出：

css 复制代码 
lvarchar: ROW(567        ,ROW('Sarah               ','Jones               '),17         )

例3：

ini 复制代码 
fetch a unnamed SQLROW column into a Struct object
s = "create table teachers (person row(id int, name row(first char(20), last char(20)), age int),dept char (20))";
stmt.executeUpdate(s);
s = "insert into teachers values ('row(100, row(Bill, Smith), 27)', 'physics')";
stmt.executeUpdate(s);
pstmt = conn.prepareStatement("select person from teachers");
rs = pstmt.executeQuery();
rs.next();
Struct person = (Struct) rs.getObject(1);
String personRowType = person.getSQLTypeName();
System.out.println("person row description: " + personRowType);
Integer id;
Struct name;
Integer age;
Object[] elements;
elements = person.getAttributes();
id = (Integer) elements[0];
name = (Struct) elements[1];
age = (Integer) elements[2];
System.out.println("person.id: " + id);
System.out.println("person.age: " + age);
String nameRowType = name.getSQLTypeName();
System.out.println("name row description: " + nameRowType);
String first = (String) elements[0];
String last = (String) elements[1];
System.out.println("name.first: " + first);
System.out.println("name.last: " + last);

输出：

sql 复制代码 
person row description:  row ( id int , name row ( first char(20) , last char(20) ) , age int ) 
person.id: 100
person.age: 27
name row description: name row ( first char(20) , last char(20) )  // row前的name是列名
name.first: Bill                
name.last: Smith

例4：

ini 复制代码 
inserting a Struct object into a named row
public class GenericStruct implements java.sql.Struct {
   private Object[] attributes = null;
   private String   typeName   = null;
   
   GenericStruct() {
   }
   GenericStruct(String name, Object[] obj) {
       typeName = name;
       attributes = obj;
   }
   public String getSQLTypeName() {
       return typeName;
   }
   public Object[] getAttributes() {
       return attributes;
   }
   public Object[] getAttributes(Map map) throws SQLException {
       return attributes;
   }
   public void setAttributes(Object[] objArray) {
       attributes = objArray;
   }
   public void setSQLTypeName(String name) {
       typeName = name;
   }
}
s = "create table teachers (person person_t, dept char (20))";
stmt.executeUpdate(s);
PreparedStatement pstmt;
ResultSet rs;
GenericStruct gs;
String rowType;
pstmt = conn.prepareStatement("insert into teachers values (?, 'Math')");
Object[] name = new Object[2];
name[0] = new String("Jane");
name[1] = new String("Smith");
rowType = "row(first char(20), last char(20))";
gs = new GenericStruct(rowType, name);
Object[] person = new Object[3];
person[0] = new Integer(99);
person[1] = gs;
person[2] = new Integer(56);
rowType = "row(id int, name row(first char(20), last char(20)), age int)";
gs = new GenericStruct(rowType, person);
pstmt.setObject(1, gs);
pstmt.executeUpdate();
pstmt.close();
pstmt = conn.prepareStatement("select person::lvarchar from teachers");
rs = pstmt.executeQuery();
while (rs.next()) {
   String s = rs.getString(1);
System.out.println("lvarchar: " + s);
}

输出：

css 复制代码 
lvarchar: ROW(99         ,ROW('Jane                ','Smith               '),56         )

例5：

ini 复制代码 
Fetching and inserting a row(i int, b boolean) column
s = "create table row_tab (int_col int, row_col r1_t)";
stmt.executeUpdate(s);
s = "insert into row_tab (int_col, row_col) values (?, ?)";
pstmt = conn.prepareStatement(s);
java.util.Map customtypemap = conn.getTypeMap();
customtypemap.put("r1_t", Class.forName("com.jdbc.demo.r1_t"));
r1_t row = new r1_t(99, true);
pstmt.setInt(1, 1);
pstmt.setObject(2, row);
pstmt.executeUpdate();
// Select (i) -
// Fetch data using getObject() with customized type maping
s = "select int_col, row_col from row_tab order by int_col";
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery(s);
rs.next();
int intret = rs.getInt("int_col");
row = (r1_t) rs.getObject("row_col");
System.out.println(row); // 输出：int_col: 99    bool_col: true
// ---------------------------------
// Selecting data as java.sql.Struct 
// ---------------------------------
Vector objVector = new Vector();
String s = "select int_col, row_col from row_tab order by int_col";
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery(s);
rs.next();
Struct row = (Struct) rs.getObject("row_col", null);
Object[] objArray = row.getAttributes();
for (int i = 0; i < objArray.length; i++) {
   System.out.println("\t\tfield: " + objArray[i]);
}

输出：

ini 复制代码 
        field: 99
        field: true
// -------------------------------------------------------
// Insert data using java.sql.Struct objects from previous select.
// -------------------------------------------------------
// 清空之前数据，略
s = "insert into row_tab values (?, ?)";
pstmt = conn.prepareStatement(s);
for (int i = 0; i < objVector.size(); i++) {
   pstmt.setInt(1, i);
   pstmt.setObject(2, objVector.get(i));
   pstmt.executeUpdate();
}
String s = "select int_col, row_col::lvarchar from row_tab order by int_col";
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery(s);
rs.next();
System.out.println(rs.getString(2)); // 输出：row_col       ROW(99         ,'t')

例6：

ini 复制代码 
s = "create table row_tab (int_col int, row_col r2_t)";
stmt.executeUpdate(s);
java.util.Map customtypemap = conn.getTypeMap();
customtypemap.put("r2_t", Class.forName("r2_t"));
String s = "insert into row_tab (int_col, row_col) values (?, ?)";
pstmt = conn.prepareStatement(s);
TreeSet set = new TreeSet();
set.add(new Long(1234567890));
set.add(new Long(-1234567890));
set.add(new Long(5));
row = new r2_t(1.67e30, set, 99);
pstmt.setInt(1, 1);
pstmt.setObject(2, row);
pstmt.executeUpdate();
String s = "select int_col, row_col from row_tab order by int_col";
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery(s);
rs.next();
r2_t row = (r2_t) rs.getObject("row_col");
System.out.println(row);

输出：

yaml 复制代码 
dbl_col: 1.67E30
int_col: 99
mset_col: 
    element: -1234567890
    element: 5
    element: 1234567890

例7：

ini 复制代码 
s = "create table row_tab (int_col int, row_col row(f float, l list(lvarchar not null), i int))";
stmt.executeUpdate(s);
s = "insert into row_tab (int_col, row_col) values (?, ?)";
pstmt = conn.prepareStatement(s);
GenericStruct struct = null; // 同例4的GenericStruct 
Object[] objArray = null;
ArrayList list = null;
list = new ArrayList();
list.add(new String("John Smith"));
list.add(new String("Granny Apple"));
list.add(new String("Barry White"));
objArray = new Object[3];
objArray[0] = new Double(1.67e30);
objArray[1] = list;
objArray[2] = new Integer(99);
struct = new GenericStruct(rowDesc, objArray);
pstmt.setInt(1, 1);
pstmt.setObject(2, struct);
pstmt.executeUpdate();
s = "select int_col, row_col from row_tab order by int_col";
rs = stmt.executeQuery(s);
rs.next();
Struct row = (Struct) rs.getObject("row_col");
System.out.println("Class: " + row.getClass().getName());
System.out.println("SQLTypeName: " + row.getSQLTypeName());
Object[] objArray = row.getAttributes();
for (int i = 0; i < objArray.length; i++) {
   System.out.println("field: " + objArray[i]);
}

输出：

yaml 复制代码 
Class: com.gbasedbt.jdbc.IfxStruct
SQLTypeName:  row ( f float , l list (  lvarchar not null) , i int ) 
field: -1.67E30
field: [Roger Jones, Jeff Brown]
field: -99

本文通过一系列示例展示介绍了如何在 GBase 8s 的 JDBC 环境中使用 ROW 类型。如果你在实践中遇到任何问题，欢迎随时在社区中提问，我们在这里为你提供支持！

原文链接：www.gbase.cn/community/p...

更多精彩内容尽在南大通用GBase技术社区，南大通用致力于成为用户最信赖的数据库产品供应商。

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