Kingbase Create Type 语句使用

Kingbase create type类型创建语句

说明：

KingbaseES 数据库中，可以通过CREATE TYPE语句定义一种新的数据类型。
有八种形式的CREATE TYPE。它们分别创建组合类型、枚举类型、 范围类型、基础类型、shell 类型、嵌套表类型、可变数组类型和对象类型。下文将依次讨论这些形式。

1.组合类型：

组合类型本质上和表的行类型相同，但是如果只想定义一种类型，使用 CREATE TYPE避免了创建一个实际的表。

语法：
CREATE TYPE name AS
( [ attribute_name data_type [ COLLATE collation ] [, ... ] ] )

示例：
create type comb_type as (c1 int , c2 varchar2(20) );

create table combtable (c1 int , c2 varchar2(20) , c3 varchar2(20));

insert into combtable values(1,'zhangsan','beijing'),(2,'lisi','shanghai');

declare 
comb comb_type;
begin 
	for i in (select c1 , c2  from combtable) loop 
	  select i.c1 , i.c2  into comb from dual;
	  raise notice 'comb_type = %',comb;
	end loop ;
end 

create or replace FUNCTION getcomb() RETURNS SETOF comb_type AS $$
    select c1 , c2 FROM combtable 
$$ LANGUAGE SQL;

select * from getcomb();

2.枚举类型：

枚举类型需要一个带引号的标签构成的列表，每一个标签长度必须不超过 NAMEDATALEN字节（在标准的 KingbaseES编译中是 64 字节）。

语法：
CREATE TYPE name AS ENUM
    ( [ 'label' [, ... ] ] )

示例：
CREATE TYPE enumtype AS ENUM ('first', 'second', 'third');

CREATE TABLE enumtable (
    id serial,
    status enumtype
);

insert into enumtable(status) values('first') ,('second');

select * from enumtable;

3.范围类型：

语法：
CREATE TYPE name AS RANGE (
    SUBTYPE = subtype
    [ , SUBTYPE_OPCLASS = subtype_operator_class ]
    [ , COLLATION = collation ]
    [ , CANONICAL = canonical_function ]
    [ , SUBTYPE_DIFF = subtype_diff_function ]
)
Range类型的输入格式：
'(lower-bound,upper-bound)'
'(lower-bound,upper-bound]'
'[lower-bound,upper-bound)'
'[lower-bound,upper-bound]'
'empty'

其中，"(" 和 ")" 表示定义的范围不包括此元素，"[" 和 "]" 表示定义的范围包括此元素，'empty' 表示空，空表示范围内不包含任何东西。

示例：
CREATE TYPE float8range AS RANGE (subtype = float8, subtype_diff = float8mi);

create table rangetable (id serial , num float8range);

insert into rangetable(num) values('(1.12,3.45)') , ('(1.12,3.45)');

select * from rangetable;

4.基础类型：

语法：
CREATE TYPE name (
    INPUT = input_function,
    OUTPUT = output_function
    [ , RECEIVE = receive_function ]
    [ , SEND = send_function ]
    [ , TYPMOD_IN = type_modifier_input_function ]
    [ , TYPMOD_OUT = type_modifier_output_function ]
    [ , ANALYZE = analyze_function ]
    [ , INTERNALLENGTH = { internallength | VARIABLE } ]
    [ , PASSEDBYVALUE ]
    [ , ALIGNMENT = alignment ]
    [ , STORAGE = storage ]
    [ , LIKE = like_type ]
    [ , CATEGORY = category ]
    [ , PREFERRED = preferred ]
    [ , DEFAULT = default ]
    [ , ELEMENT = element ]
    [ , DELIMITER = delimiter ]
    [ , COLLATABLE = collatable ]
)

5.shell 类型：

shell 类型仅仅是一种用于后面要定义的类型的占位符，通过发出一个不带除类型名之外其他参数的CREATE TYPE命令可以创建这种类型。

语法：
CREATE TYPE name

6.嵌套表类型：

语法：
CREATE TYPE name AS TABLE OF datatype [NOT NULL]

示例：
CREATE TYPE int_table AS TABLE OF INT NOT NULL;

declare 
inttab int_table;
i INT;
begin 
	inttab := int_table(1,2,3,4,5);
	i := inttab.first();
	WHILE i IS NOT NULL LOOP
	  RAISE NOTICE 'inttab(%) is %', i, inttab(i);
	  i := inttab.next(i);
	END LOOP;
end 

7.可变数组类型：

可变数组的下标索引类型为 INT 并且从 1 开始。与嵌套表不同，可变数组在定义的时候需要指定最大元素个数，使用中不能超过该限制。

语法：
CREATE TYPE name AS VARRAY(size_limit) OF datatype [NOT NULL]

示例：
create type varray100 is varray (20) of int;

declare 
var varray100 = varray100();
begin 
	var.extend();
	RAISE NOTICE 'var lenght %', var.count();
	var.extend(10);
	RAISE NOTICE 'var lenght %', var.count();
	
	var.delete;
	var.extend();
	var(1) := 7;
	var.extend(19, 1);
	RAISE NOTICE 'var lenght %', var.count();
	RAISE NOTICE 'var first() = %', var.first();
    RAISE NOTICE 'var last() = %', var.last();
end 

8.对象类型：

语法：
CREATE [ OR REPLACE ] TYPE name [ FORCE ] [ AUTHID { CURRENT_USER | DEFINER } ]
{ AS | IS } OBJECT (
    attribute_name data_type [, ... ]
    [, subprogram_spec [, ... ] ]
    [, constructor_spec [, ... ] ]
)
这里 subprogram_spec 是以下之一：
    { STATIC | MEMBER } FUNCTION function_name
        [ ( [ argname [ argmode ] argtype [ { DEFAULT | := } default_expr ] [, ...] ] ) ]
        { RETURNS | RETURN } rettype ]
    { STATIC | MEMBER } PROCEDURE procedure_name
        [ ( [ argname [ argmode ] argtype [ { DEFAULT | := } default_expr ] [, ...] ] ) ]

constructor_spec 是:
    CONSTRUCTOR FUNCTION name
        [ ( [ SELF IN OUT name ] [, argname [ argmode ] argtype [ { DEFAULT | := } default_expr ] [, ...] ] ) ]
        { RETURNS | RETURN } SELF AS RESULT

示例：
CREATE OR REPLACE TYPE objtype FORCE AUTHID CURRENT_USER AS OBJECT(
  f1 int,
  f2 varchar2(10),
  MEMBER FUNCTION memfunc(i int) RETURN INT,
  STATIC PROCEDURE staproc,
  CONSTRUCTOR FUNCTION objtype(self in out objtype) RETURN SELF AS RESULT
);

CREATE OR REPLACE TYPE BODY objtype AS
  MEMBER FUNCTION memfunc(i int) RETURN INT AS
  BEGIN
    RAISE NOTICE 'self.f1 is %', self.f1;
    RAISE NOTICE 'self.f2 is %', f2;
    RETURN i;
  END;
  
  STATIC PROCEDURE staproc AS
  BEGIN
    RAISE NOTICE 'this is a static procedure in object type';
  END;	

  CONSTRUCTOR FUNCTION objtype(self in out objtype) RETURN SELF AS RESULT as
  begin
	f1 := 1;
    self.f2 := 'a';
    RETURN ;
  END;
END;

CREATE TABLE tb1(i objtype);
INSERT INTO tb1 select * from objtype(2, 'b'); 
INSERT INTO tb1 select * from objtype();

SELECT * FROM tb1;

CALL objtype.staproc();