Question

我在mySQL查询中有一个IF语句，它运行良好：

 GROUP_CONCAT(DISTINCT CONCAT("animal:",if(animal.name="monkey","fred",""),",color: ",animal.color) SEPARATOR " <br>") AS animals

我现在要添加一个ELSEIF：

  GROUP_CONCAT(DISTINCT CONCAT("animal:",if(animal.name="monkey","fred","")elseif(animal.name="cat","jane",""),",color: ",animal.color) SEPARATOR " <br>") AS animals

但是我收到了一条错误消息：

语法错误或访问冲突：1064 SQL中有错误语法

Answer 1

＆＃34; if elseif endif＆＃34;是一个控制语句，而if（）是MySQL中的一个函数。虽然它们具有相同的名称，但它们是不同的东西。

如果您有多个选项，则可以使用CASE而不是IF。

SELECT 
    GROUP_CONCAT(DISTINCT CONCAT("animal:",
      CASE animal.name
        WHEN "monkey" THEN "fred"
        WHEN "cat" THEN "jane"
        ELSE "other"
      END,
      ",color: ",animal.color) SEPARATOR " <br>"
    ) AS animals
FROM (
  SELECT 'monkey' AS 'name', 'brown' AS 'color'
  UNION
  SELECT 'cat', 'white'
  UNION
  SELECT 'dog', 'black'
  ) AS animal

Answer 2

您必须在if

的else部分添加if

group_concat(distinct concat("animal:",if(animal.name="monkey","fred",if(animal.name="cat","jane","")),",color: ",animal.color) separator " <br>") as animals

case语法几乎相同

group_concat(distinct concat("animal:",case animal.name when "monkey" then "fred" when "cat" then "jane" case "dog" then "donald" else "",",color: ",animal.color) separator " <br>") as animals

如何在GROUP_CONCAT中使用ELSE IF？

2 个答案: