如何从列表中获取选定列名称

Question

如何从表格中选择列名称？

在我的表中，我总共有10行，但我只想显示5行。这就是我所选列的意思。

对于上述情况将会是什么查询？

我使用下面的查询检索所有列：

SELECT column_name 
FROM information_schema.columns 
WHERE table_name = 'table name' 

Answer 1

最后我找到了查询...即，

SELECT DISTINCT column_name 
FROM information_schema.columns 
WHERE table_name IN (SELECT table_name FROM information_schema.tables 
        WHERE table_schema='your database') 
    AND column_name IN (SELECT column_name FROM information_schema.columns 
         WHERE column_name IN ('column1','column2','etc') 
         AND table_name IN ('your table name')) 

Answer 2

与Mysql Limit

SELECT column_name FROM information_schema.columns WHERE table_name = 'table name' limit 5 

而对于限随机

SELECT column_name FROM information_schema.columns WHERE table_name = 'table name' 
ORDER BY RAND() 
LIMIT 5 

Answer 3

您必须检索行的条件：

SELECT coloumn from table_name WHERE condition 

注：例如，对于条件可以像“ no_of_employees = 2”

上面的示例将检索行，其中coloumn“no_of_employees”为2

为了得到一个随机行，请参阅本岗位：http://www.petefreitag.com/item/466.cfm

选择一个随机行与MySQL：

SELECT column FROM table 
ORDER BY RAND() 
LIMIT 1 

选择RAN DOM排在PostgreSQL：

SELECT column FROM table 
ORDER BY RANDOM() 
LIMIT 1 

选择一个随机行与Microsoft SQL Server：

SELECT TOP 1 column FROM table 
ORDER BY NEWID() 
Select a random row with IBM DB2 
SELECT column, RAND() as IDX 
FROM table 
ORDER BY IDX FETCH FIRST 1 ROWS ONLY 

选择一个与Oracle的随机记录：

SELECT column FROM 
(SELECT column FROM table 
ORDER BY dbms_random.value) 
WHERE rownum = 1