DB2 SQL高级应用 High level usage

Assumes that we have a table named PRICE_CN
Columns: ID, CABLEID, PRODUCTID, PRICE
Records: 50000000, ANND1, 609, 90

1. NEW TABLE, OLD TABLE
-- a .With Update
SELECT * FROM OLD TABLE (
UPDATE PRICE_CN PRICE SET PRICE = 80 WHERE PRICE.ID = 50000000
)

--Results: The price before updated will be selected out
-- PRICE
-- 90
-- b.
-- Assumes that we only have 1 record before insert successful
SELECT COUNT(*) FROM OLD TABLE(
INSERT INTO PRICE_CN ( CABLEID, PRODUCTID, PRICE ) VALUES ( 'ANND2', 700, 1000)
)

-- Results:
-- Count
-- 1

2. INSERT WITH SELECT
-- set the price of the cable-product with the cable id 'ANND2' and productid 700 to be the price of the new cable product with cable id 'ANND3' and productid 701

INSERT INTO PRICE CN ( CABLEID, PRODUCTID, PRICE )
SELECT 'ANND3', 701, PRICE.PRICE FROM PRICE_CN AS PRICE WHERE PRICE.CABLEID='ANND2', PRICE.PRODUCTID=700

-- the results of the sub select will be the values to be insert into PRICE_CN table

3. Temp table using WITH

// Test How to select out the OLD Price with the NEW price
WITH
BEFORE_PRICE_UPDATED
AS(
SELECT * FROM OLD TABLE (
UPDATE WWPRT.PRICE_CN PRICE SET PRICE = 80 WHERE PRICE.ID = 50000000
)
)
SELECT PRICE.CABLEID, PRICE.PRODUCTID, PRICE.PRICE AS OLDPRICE, BEFOREPRICE.PRICE AS NEWPRICE
FROM WWPRT.PRICE_CN PRICE
INNER JOIN BEFORE_PRICE_UPDATED BEFOREPRICE ON BEFOREPRICE.ID = PRICE.ID AND PRICE.ID = 50000000

-- results: AFTER UPDATE, we can compare with the new one selected out from the OLD table as a tempoary table
CABLEID PRODUCTID OLDPRICE NEWPRICE
---------- ------------ ----------- -----------
ANND1 609 90 80

-- The format using WITH
WITH
TEMP1(T1COL1,T1COL2,....) AS (
SELECT COL1, COL2 FROM TABLE1 WHERE ....
),
TEMP2(T2COL,T2COL2.....) AS(
values (T2COLValue1, T2COL2Value1 ....),

(T2COLValue2, T2COL2Value2 ....),

(T2COLValue3, T2COL2Value3 ....)
) // no comma here
SELECT * FROM TABLE1, TABLE2, TEMP1, TEMP2 ......

4. Import and Export

Export.

EXPORT TO yourfile.del OF DEL
SELECT PRICE.* from yourtable

Import

import from yourfile.del of del
COMMITCOUNT 100000
insert into yourtable;
// import with matched columns,
// assume that the first column is the PK with increased auto
IMPORT FROM yourfile.del OF DEL
METHOD P ( 1, 2 )
COMMITCOUNT 100000
INSERT INTO yourschema.table(
column2, column3
);

5. MERGE INTO

MERGE INTO TARGET_TABLE
USING SOURCE_TABLE
WHEN MATCHED THEN
UPDATE ()=()
WHEN NOT MATCHED THEN
INSERT () VALUES ()

例子:

StringBuffer sb = new StringBuffer()
.append(  "merge into(select * from wwprt.price_pattern_ref_cn where pricepatternid=?)as oo" )
.append( " using(values(cast(? as varchar(2)),cast(? as integer),cast(? as varchar(3)),cast(? as char(1)),cast(? as decimal(13,2)),cast(? as decimal(13,2)))," )
.append(              "(cast(? as varchar(2)),cast(? as integer),cast(? as varchar(3)),cast(? as char(1)),cast(? as decimal(13,2)),cast(? as decimal(13,2)))," )
.append(              "(cast(? as varchar(2)),cast(? as integer),cast(? as varchar(3)),cast(? as char(1)),cast(? as decimal(13,2)),cast(? as decimal(13,2)))," )
.append(              "(cast(? as varchar(2)),cast(? as integer),cast(? as varchar(3)),cast(? as char(1)),cast(? as decimal(13,2)),cast(? as decimal(13,2)))," )
.append(              "(cast(? as varchar(2)),cast(? as integer),cast(? as varchar(3)),cast(? as char(1)),cast(? as decimal(13,2)),cast(? as decimal(13,2))))" )
.append(   " as nn(refid,refproductid,refpricetype,fromsamecable,priceusdcalc,price)" )
.append( " on oo.refid=nn.refid" )
.append( " when matched and nn.refproductid is null then delete" )
.append( " when matched then update set" )
.append(   " oo.refproductid=nn.refproductid," )
.append(   " oo.refpricetype=nn.refpricetype," )
.append(   " oo.fromsamecable=nn.fromsamecable," )
.append(   " oo.priceusdcalc=nn.priceusdcalc," )
.append(   " oo.price=nn.price" )
.append( " when not matched and nn.refproductid is not null then" )
.append(   " insert(pricepatternid,refid,refproductid,refpricetype,fromsamecable,priceusdcalc,price)" )
.append(   " values(?,nn.refid,nn.refproductid,nn.refpricetype,nn.fromsamecable,nn.priceusdcalc,nn.price)" );

return sb.toString();