如何從列表中獲取選定列名稱

Question

如何從表格中選擇列名稱？

在我的表中，我總共有10行，但我只想顯示5行。這就是我所選列的意思。

對於上述情況將會是什麼查詢？

我使用下面的查詢檢索所有列：

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

Answer 1

最後我找到了查詢...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

與Mysql Limit

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

而對於限隨機

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

Answer 3

您必須檢索行的條件：

SELECT coloumn from table_name WHERE condition 

注：例如，對於條件可以像「 no_of_employees = 2」

上面的示例將檢索行，其中coloumn「no_of_employees」爲2

爲了得到一個隨機行，請參閱本崗位：http://www.petefreitag.com/item/466.cfm

選擇一個隨機行與MySQL：

SELECT column FROM table 
ORDER BY RAND() 
LIMIT 1 

選擇RAN DOM排在PostgreSQL：

SELECT column FROM table 
ORDER BY RANDOM() 
LIMIT 1 

選擇一個隨機行與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 

選擇一個與Oracle的隨機記錄：

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