從查詢中創建一個包含START WITH的序列

Question

如何創建一個序列，其中的START WITH值來自查詢？

我想是這樣的： CREATE SEQUENCE "Seq" INCREMENT BY 1 START WITH (SELECT MAX("ID") FROM "Table");

但是，我得到ORA-01722錯誤

Answer 1

START WITH子句接受一個整數。您可以動態地創建「Create sequence」語句，然後使用execute immediate執行以實現此目的。

declare 
    l_new_seq INTEGER; 
begin 
    select max(id) + 1 
    into l_new_seq 
    from test_table; 

    execute immediate 'Create sequence test_seq_2 
         start with ' || l_new_seq || 
         ' increment by 1'; 
end; 
/

查看這些鏈接。

http://download.oracle.com/docs/cd/B14117_01/server.101/b10759/statements_6014.htm
http://download.oracle.com/docs/cd/B19306_01/appdev.102/b14261/executeimmediate_statement.htm

Answer 2

這裏我有我的例子非常有效：

declare 
ex number; 
begin 
    select MAX(MAX_FK_ID) + 1 into ex from TABLE; 
    If ex > 0 then 
    begin 
      execute immediate 'DROP SEQUENCE SQ_NAME'; 
     exception when others then 
     null; 
    end; 
    execute immediate 'CREATE SEQUENCE SQ_NAME INCREMENT BY 1 START WITH ' || ex || ' NOCYCLE CACHE 20 NOORDER'; 
    end if; 
end;