Question

我目前正在使用SQL命令

Select * from where name='john'

无论查询是否可以返回20，例如

Select * from where name='john' or return = 20

Answer 1

修改如果你有一个oracle数据库，你可以这样做：

SELECT * FROM dual WHERE 1=0 UNION SELECT '20' FROM dual;

Answer 2

检查我的答案

 if exists (Select * from item where ItemName='ABC Daycare1')
  begin
  Select * from item where ItemName='ABC Daycare1'
  end
  else
  select '20'

Answer 3

尝试运行此功能。这应返回最高结果（由于自定义排序而不是20），然后当名称与值不匹配时，它返回'Mark'和20

<强> SQL

IF OBJECT_ID('tempdb..#temp') IS NOT NULL DROP TABLE #temp

CREATE TABLE #temp (id int NOT NULL, name varchar(255) NOT NULL)

INSERT INTO #temp (id, name) VALUES (88,'John')
INSERT INTO #temp (id, name) VALUES (20,'Mark')

SELECT TOP 1 
    * 
FROM #temp 
WHERE (name = 'Mark' OR name = 'John') 
ORDER BY (
    CASE
        WHEN id = 20 THEN 0 ELSE 1
    END) DESC

MySQL - MySQL fiddle

IF OBJECT_ID('tempdb..#temp') IS NOT NULL DROP TABLE #temp

CREATE TABLE #temp (id int NOT NULL, name varchar(255) NOT NULL)

INSERT INTO #temp (id, name) VALUES (88,'John')
INSERT INTO #temp (id, name) VALUES (20,'Mark')

SELECT 
    * 
FROM temp 
WHERE (name = 'Mark' OR name = 'John') 
ORDER BY (
    CASE
        WHEN id = 20 THEN 0 ELSE 1
    END) DESC
LIMIT 1

从sql命令返回值

3 个答案: