多维 Collection
虽然 collection 只有一维的，但可以模型一个多维的。创建一个 collection，其每个元素也是 collection 。例如，创建一个 varray 的 nested table，一个 varray 的 varray，一个 nested table 的 varray 等。
示例1：演示多维 varray
DECLARE
TYPE t1 IS VARRAY(10) OF INTEGER;
TYPE nt1 IS VARRAY(10) OF t1; -- multilevel varray type
va t1 := t1(2,3,5);
-- initialize multilevel varray
nva nt1 := nt1(va, t1(55,6,73), t1(2,4), va);
i INTEGER;
va1 t1;
BEGIN
-- multilevel access
i := nva(2)(3); -- i will get value 73
DBMS_OUTPUT.PUT_LINE('I = ' || i);-- add a new varray element to nva
nva.EXTEND;
-- replace inner varray elements
nva(5) := t1(56, 32);
nva(4) := t1(45,43,67,43345);
-- replace an inner integer element
nva(4)(4) := 1; -- replaces 43345 with 1
-- add a new element to the 4th varray element
-- and store integer 89 into it.
nva(4).EXTEND;
nva(4)(5) := 89;
END;
/
示例2：演示多维 nested table .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }
DECLARE
TYPE tb1 IS TABLE OF VARCHAR2(20);
TYPE Ntb1 IS TABLE OF tb1; -- table of table elements
TYPE Tv1 IS VARRAY(10) OF INTEGER;
TYPE ntb2 IS TABLE OF tv1; -- table of varray elements
vtb1 tb1 := tb1('one', 'three');vntb1 ntb1 := ntb1(vtb1);
vntb2 ntb2 := ntb2(tv1(3,5), tv1(5,7,3));
-- table of varray elements
BEGIN
vntb1.EXTEND;
vntb1(2) := vntb1(1);
-- delete the first element in vntb1
vntb1.DELETE(1);
-- delete the first string
-- from the second table in the nested table
vntb1(2).DELETE(1);
END;
/
示例3：演示多维 associative array .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }
DECLARE
TYPE tb1 IS TABLE OF INTEGER INDEX BY PLS_INTEGER;
-- the following is index-by table of index-by tables
TYPE ntb1 IS TABLE OF tb1 INDEX BY PLS_INTEGER;
TYPE va1 IS VARRAY(10) OF VARCHAR2(20);
-- the following is index-by table of varray elements
TYPE ntb2 IS TABLE OF va1 INDEX BY PLS_INTEGER;
v1 va1 := va1('hello', 'world');v2 ntb1;
v3 ntb2;
v4 tb1;
v5 tb1; -- empty table
BEGIN
v4(1) := 34;
v4(2) := 46456;
v4(456) := 343;
v2(23) := v4;
v3(34) := va1(33, 456, 656, 343);
-- assign an empty table to v2(35) and try again
v2(35) := v5;
v2(35)(2) := 78; -- it works now
END;
/