MySQL选择查询值
鉴于下表:MySQL选择查询值,mysql,Mysql,鉴于下表: id name value 1 primary value1 2 secudary value1 3 primary value1 4 secudary value1 5 primary value3 6 secudary value3 我需要从表名中选择*,其中value=“value1” 但是我不能同时从主字段和辅助字段中选择信息。 我想检查是否有SELECT*FROM table\u name
id name value
1 primary value1
2 secudary value1
3 primary value1
4 secudary value1
5 primary value3
6 secudary value3
我需要从表名中选择*,其中value=“value1”
但是我不能同时从主字段和辅助字段中选择信息。我想检查是否有
SELECT*FROM table\u name WHERE value=“value1”和name=“primary”
的任何记录,如果有记录我使用此结果,如果没有记录我搜索SELECT*FROM table\u name WHERE value=“value1”和name=“secundary”
有什么想法吗?您需要声明一个变量,选择要加载变量的记录,检查它是否有值,并使用if语句进行选择。(我在存储过程中执行此操作)
将主栏和次栏分开如果这有帮助,请将其标记为答案。谢谢
declare $found int;
set $found = null;
set $found= (select id FROM table_name WHERE value = "value1" and name = "primary" limit 1);
if ($found is null) then
SELECT * FROM table_name WHERE value = "value1" and name = "secundary";
else
SELECT * FROM table_name WHERE value = "value1" and name = "primary";
end if;