一、原题 Examine the structure of the PROMOS table: Name Null Type PROMO_ID NOT NULL NUMBER(3) PROMO_NAME VARCHAR2(30) PROMO_START_DATE NOT NULL DATE PROMO_…
一、原题 View the Exhibit and examine the structure of the PROMOTIONS table. Which SQL statements are valid? (Choose all that apply.) A. SELECT promo_id, DECODE(NVL(promo_cost,0), promo_cost,promo_cost * 0.25, 100) "Discount" FROM promo…
一、原题 Examine the data in the LIST_PRICE and MIN_PRICE columns of the PRODUCTS table: LIST_PRICE MIN_PRICE 10000 8000 20000 30000 30000 Which two expressions give the same output? (Choose two.) A. NVL(NULLIF(list_price, min_price)…
一、原题 Examine the structure of the SHIPMENTS table:Name Null TypePO_ID NOT NULL NUMBER(3) PO_DATE NOT NULL DATE SHIPMENT_DATE NOT NULL DATE SHIPMENT_MODE VARCH…
一、原题 Examine the data in the PROMO_BEGIN_DATE column of the PROMOTIONS table: PROMO_BEGIN _DATE 04-jan-00 10-jan-00 15-dec-99 18-oct-98 22-aug-99 You want to display the number of promotions started in 1999 and 2000. Which query gives the correct outp…
sql
WITH x AS (
SELECT 1 AS id,a1 AS name FROM DUAL UNION ALL
SELECT 2 AS id,null AS name FROM DUAL
)
SELECT id, CASE WHEN name IS NULL THEN 我是null ELSE 有值: || name END AS "通过case when判断", decode(name,NULL,我是null,有值&…
一、case when case when 类似我们的if ...else ,判断语句 语法如下: CASE expr WHEN expr1 THEN return_expr1 [WHEN expr2 THEN return_expr2 ... WHEN exprn THEN return_exprn ELSE else_expr] END 第二种延伸用法: CASE …