如何向連接行添加附加信息?向連接行添加附加信息
SELECT column1, column2
FROM table1
LEFT JOIN table2
ON column1 = col1_table2 //The row which matches with this join should have additional information e.g. "'joined' AS info
非常感謝您的幫助!
如何向連接行添加附加信息?向連接行添加附加信息
SELECT column1, column2
FROM table1
LEFT JOIN table2
ON column1 = col1_table2 //The row which matches with this join should have additional information e.g. "'joined' AS info
非常感謝您的幫助!
如果我明白你的問題,這應該工作:
SELECT
t1.column1,
t1.column2,
CASE WHEN t2.col1_table2 IS NOT NULL THEN 'joined' END AS info
FROM table1 t1
LEFT JOIN table2 t2 ON t1.column1 = t2.col1_table2
從我身上。你的回答是正確的,你是第一位的。 – 2012-04-06 16:13:13
非常感謝! – shub 2012-04-06 16:14:34
試試這個:
SELECT column1,
column2,
CASE WHEN col1_table2 IS NOT NULL THEN 'joined' END AS additional_field
FROM table1
LEFT JOIN table2 ON column1 = col1_table2
咦?你的意思是該行應該包含該信息,或者列名應該附加連接?另外,什麼RDBMS? – 2012-04-06 16:08:57
你想完成什麼?您想要在某處添加字符串「加入」來標識來自連接表的數據,還是發現了連接的記錄? – Gratzy 2012-04-06 16:10:02